Academic literature on the topic 'Bacterial metabolic activity'
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Journal articles on the topic "Bacterial metabolic activity"
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Babu, Jegdish, Cohen Blair, Shiloah Jacob, and Ofek Itzhak. "Inhibition ofStreptococcus gordoniiMetabolic Activity in Biofilm by Cranberry Juice High-Molecular-Weight Component." Journal of Biomedicine and Biotechnology 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/590384.
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Previous studies demonstrated that a cranberry high-molecular-mass, nondialyzable material (NDM) can inhibit adhesion of numerous species of bacteria and prevents bacterial coaggregation of bacterial pairs. Bacterial coaggregation leads to plaque formation leading to biofilm development on surfaces of oral cavity. In the present study, we evaluated the effect of low concentrations of NDM onStreptococcus gordoniimetabolic activity and biofilm formation on restorative dental surfaces. We found that the NDM selectively inhibited metabolic activity ofS. gordonii, without affecting bacterial viability. Inhibiting the metabolic activity of bacteria in biofilm may benefit the health of the oral cavity.
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Sabra, Sherifa. "Elimination Virulent-pathogenic-biofilm Bacteria Using Highland-wild Salvia officinalis Preserve Bacterial-infection-control." Biotechnology and Bioprocessing 2, no. 2 (February 2, 2021): 01–04. http://dx.doi.org/10.31579/2766-2314/021.
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This work for this title "Elimination Virulent-pathogenic-biofilm (VPB) Bacteria Using Highland-wild (HLW) Salvia officinalis (S. officinalis) Preserve Bacterial-infection-control (BIC)"; the aim was to prove the importance of HLW S. officinalis extracts have therapeutic herbal importance. Through its effected on the isolated VPB bacteria caused infection diseases that may preserve BIC for individuals, which proved the effectiveness of the HLW S. officinalis daily use or therapeutic use. S. officinalis specimens were collected during the flowering period from HLW, Taif, KSA. Essential oils (EOs) were equipped and biofilms preparation, then laboratory methods deputy for anti-biofilms formation activity and biofilms elimination activity, finally biofilms metabolic grades measurement. The bacterial metabolic grades of anti-biofilms formation activity showed the HLW S. officinalis EOs extracts eliminated VPB bacteria and effects were greater. Anywhere Staphylococcous aureus (S. aureus) and Streptococcus pyogenes (S. pyogenes) were eliminated until 60 hours. While Pseudomonas aeruginosa (PA) was eliminated at 72 hours. The bacterial metabolic grades of biofilms elimination activity found the HLW S. officinalis EOs extracts eliminated within 8 hours (S. aureus and S. pyogenes), PA was to 10 hours. Concluded the HLW S. officinalis EOs extracts had proven its ability to eliminate VPB bacteria, and from that, it proven on the type used with healthy characteristics to maintain health and BIC. Recommendation: That topic recommend using the appropriate HLW S. officinalis EOs extracts for individuals daily to maintain the general health. In cases of illness, person must ask the "Specialized Physician" to determine the healthy and curative amount to use.
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Simon, K. S., J. Gibert, P. Petitot, and R. Laurent. "Spatial and temporal patterns of bacterial density and metabolic activity in a karst aquifer." Fundamental and Applied Limnology 151, no. 1 (March 23, 2001): 67–82. http://dx.doi.org/10.1127/archiv-hydrobiol/151/2001/67.
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Smith, Alexandra H., and Roderick I. Mackie. "Effect of Condensed Tannins on Bacterial Diversity and Metabolic Activity in the Rat Gastrointestinal Tract." Applied and Environmental Microbiology 70, no. 2 (February 2004): 1104–15. http://dx.doi.org/10.1128/aem.70.2.1104-1115.2004.
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ABSTRACT The effect of dietary condensed tannins (proanthocyanidins) on rat fecal bacterial populations was ascertained in order to determine whether the proportion on tannin-resistant bacteria increased and if there was a change in the predominant bacterial populations. After 3 weeks of tannin diets the proportion of tannin-resistant bacteria increased significantly (P < 0.05) from 0.3% ± 5.5% to 25.3% ± 8.3% with a 0.7% tannin diet and to 47.2% ± 5.1% with a 2% tannin diet. The proportion of tannin-resistant bacteria returned to preexposure levels in the absence of dietary tannins. A shift in bacterial populations was confirmed by molecular fingerprinting of fecal bacterial populations by denaturing gradient gel electrophoresis (DGGE). Posttreatment samples were generally still distinguishable from controls after 3.5 weeks. Sequence analysis of DGGE bands and characterization of tannin-resistant isolates indicated that tannins selected for Enterobacteriaceae and Bacteroides species. Dot blot quantification confirmed that these gram-negative bacterial groups predominated in the presence of dietary tannins and that there was a corresponding decrease in the gram-positive Clostridium leptum group and other groups. Metabolic fingerprint patterns revealed that functional activities of culturable fecal bacteria were affected by the presence of tannins. Condensed tannins of Acacia angustissima altered fecal bacterial populations in the rat gastrointestinal tract, resulting in a shift in the predominant bacteria towards tannin-resistant gram-negative Enterobacteriaceae and Bacteroides species.
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Pope, Emily, Bradley Haltli, Russell G. Kerr, and Ali Ahmadi. "Effects of Matrix Composition and Temperature on Viability and Metabolic Activity of Microencapsulated Marine Bacteria." Microorganisms 10, no. 5 (May 10, 2022): 996. http://dx.doi.org/10.3390/microorganisms10050996.
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To enhance the discovery of novel natural products, various innovations have been developed to aid in the cultivation of previously unculturable microbial species. One approach involving the microencapsulation of bacteria has been gaining popularity as a new cultivation technique, with promising applications. Previous studies demonstrated the success of bacterial encapsulation; however, they highlighted that a key limitation of encapsulating bacteria within agarose is the high temperature required for encapsulation. Encapsulation of bacteria within agarose typically requires a temperature high enough to maintain the flow of agarose through microfluidic devices without premature gelation. Given the sensitivity of many bacterial taxa to temperature, the effect of various agarose-based encapsulating matrices on marine bacterial viability was assessed to further develop this approach to bacterial culture. It was determined that lowering the temperature of encapsulation via the use of low-gelling-temperature agarose, as well as the addition of nutrients to the matrix, significantly improved the viability of representative marine sediment bacteria in terms of abundance and metabolic activity. Based on these findings, the use of low-gelling-temperature agarose with supplemental nutrients is recommended for the encapsulation of marine bacteria obtained from temperate habitats.
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Unge, Annika, Riccardo Tombolini, Lars Mølbak, and Janet K. Jansson. "Simultaneous Monitoring of Cell Number and Metabolic Activity of Specific Bacterial Populations with a Dualgfp-luxAB Marker System." Applied and Environmental Microbiology 65, no. 2 (February 1, 1999): 813–21. http://dx.doi.org/10.1128/aem.65.2.813-821.1999.
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ABSTRACT A dual marker system was developed for simultaneous quantification of bacterial cell numbers and their activity with the luxABand gfp genes, encoding bacterial luciferase and green fluorescent protein (GFP), respectively. The bioluminescence phenotype of the luxAB biomarker is dependent on cellular energy status. Since cellular metabolism requires energy, bioluminescence output is directly related to the metabolic activity of the cells. By contrast, GFP fluorescence has no energy requirement. Therefore, by combining these two biomarkers, total cell number and metabolic activity of a specific marked cell population could be monitored simultaneously. Two different bacterial strains, Escherichia coli DH5α and Pseudomonas fluorescens SBW25, were chromosomally tagged with the dual marker cassette, and the cells were monitored under different conditions by flow cytometry, plate counting, and luminometry. During log-phase growth, the luciferase activity was proportional to the number of GFP-fluorescent cells and culturable cells. Upon entrance into stationary phase or during starvation, luciferase activity decreased due to a decrease in cellular metabolic activity of the population, but the number of GFP-fluorescing cells and culturable cells remained relatively stable. In addition, we optimized a procedure for extraction of bacterial cells from soil, allowing GFP-tagged bacteria in soil samples to be quantitated by flow cytometry. After 30 days of incubation of P. fluorescensSBW25::gfp/lux in soil, the cells were still maintained at high population densities, as determined by GFP fluorescence, but there was a slow decline in luciferase activity, implicating nutrient limitation. In conclusion, the dual marker system allowed simultaneous monitoring of the metabolic activity and cell number of a specific bacterial population and is a promising tool for monitoring of specific bacteria in situ in environmental samples.
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Bojic, Gordana, Svetlana Golocorbin-Kohn, Maja Stojancevic, Momir Mikov, and Ljiljana Suvajdzic. "Metabolic activity of gut microbiota and xenobiotics." Zbornik Matice srpske za prirodne nauke, no. 128 (2015): 47–55. http://dx.doi.org/10.2298/zmspn1528047b.
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The intestine habitat is the natural collection of symbiotic microorganisms. The bacterial population enables many permanent metabolic activities in this environment. Inside the intestine of mammals there are an extended genome of millions of bacterial genes named microbiome. In recent years, there has been an increased interest of scientists to discover the place and the role of bio-ecological content and modulation of gut microbiota in a host organism using prebiotics, probiotics and synbiotics, which may have a great benefit for human health.
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Roth, D., and H. Lemmer. "Biofilms in Sewer Systems – Characterization of the Bacterial Biocenosis and Its Metabolic Activity." Water Science and Technology 29, no. 7 (April 1, 1994): 385–88. http://dx.doi.org/10.2166/wst.1994.0367.
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Biofilms sampled from sewers discharging domestic and trade wastewater, respectively, were characterized by determining the population densities of different groups of heterotrophic bacteria as well as by measuring their metabolic activities. Population densities of heterotrophic saprophytes, of proteolytic, amylolytic, and lipolytic bacteria as well as of ammonifying, nitrate reducing and anaerobic bacteria were determined on solid media and by MPN-tests. Metabolic activity was assessed by measuring enzyme activity of esterase, L-alanine-aminopeptidase, phosphatase, as well as of α- and β-glucosidase. Both biofilms revealed high population densities of bacteria from several metabolic groups as well as high enzyme activities. Their heterotrophic activity is in the range of or even higher than that found in high load activated sludges. The high activity of the bacterial biocenosis proves its resistance against high concentrations of chromium and nickel.
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Liu, Yuan, Ruichao Li, Xia Xiao, and Zhiqiang Wang. "Bacterial metabolism-inspired molecules to modulate antibiotic efficacy." Journal of Antimicrobial Chemotherapy 74, no. 12 (June 18, 2019): 3409–17. http://dx.doi.org/10.1093/jac/dkz230.
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AbstractThe decreasing antibiotic susceptibility of bacterial pathogens calls for novel antimicrobial therapies. Traditional screening pathways based on drug–target interaction have gradually reached the stage of diminishing returns. Thus, novel strategies are urgently needed in the fight against antibiotic-refractory bacteria, particularly for tolerant bacteria. Recently, evidence has accumulated demonstrating that microbial changes caused by bacterial metabolic processes significantly modulate antibiotic killing. A better understanding of these bacterial metabolic processes is indicating a need to screen novel metabolic modulators as potential antibiotic adjuvants. In this review, we describe the state of our current knowledge about how these bacterial metabolism-inspired molecules affect antibiotic efficacy, including potentiation and inhibition activity. In addition, the challenges faced and prospects for bringing them into clinic are also discussed. These examples may provide candidates or targets for the development of novel antibiotic adjuvants.
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Trinh, Kieu The Loan, and Nae Yoon Lee. "Recent Methods for the Viability Assessment of Bacterial Pathogens: Advances, Challenges, and Future Perspectives." Pathogens 11, no. 9 (September 16, 2022): 1057. http://dx.doi.org/10.3390/pathogens11091057.
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Viability assessment is a critical step in evaluating bacterial pathogens to determine infectious risks to public health. Based on three accepted viable criteria (culturability, metabolic activity, and membrane integrity), current viability assessments are categorized into three main strategies. The first strategy relies on the culturability of bacteria. The major limitation of this strategy is that it cannot detect viable but nonculturable (VBNC) bacteria. As the second strategy, based on the metabolic activity of bacteria, VBNC bacteria can be detected. However, VBNC bacteria sometimes can enter a dormant state that allows them to silence reproduction and metabolism; therefore, they cannot be detected based on culturability and metabolic activity. In order to overcome this drawback, viability assessments based on membrane integrity (third strategy) have been developed. However, these techniques generally require multiple steps, bulky machines, and laboratory technicians to conduct the tests, making them less attractive and popular applications. With significant advances in microfluidic technology, these limitations of current technologies for viability assessment can be improved. This review summarized and discussed the advances, challenges, and future perspectives of current methods for the viability assessment of bacterial pathogens.
Dissertations / Theses on the topic "Bacterial metabolic activity"
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Wos, Melissa Louise, and n/a. "Methods For Understanding Bacterial Metabolic Activity In Activated Sludge." Griffith University. School of Environmental Engineering, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20061031.151641.
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Biological wastewater treatment relies on the diverse and complex metabolic activities of bacteria to remove pollutants. Its success depends on the metabolic efficiency of the bacteria. Activated sludge models use parameters that attempt to depict bacterial growth and metabolic processes. However, current methods do not separate metabolic activity from growth and maintenance. As a result, activated sludge processes are misinterpreted or over-simplified. Alternative methods for gauging bacterial activity have been proposed and include the measurements of cellular derived compounds that relate specifically to energy cycling and include Nicotinamide Adenine Dinucleotide [NADH]. To date, NADH has been largely measured within activated sludge using commercial online fluorimeters with in situ probes. However, this current method provides a measure of the 'bulk' (raw) fluorescence within the system, resulting in difficulties when interpreting fluorescence data and poor sensitivity for detecting changes in intracellular [NADH]. This study has developed a more reliable method for estimating intracellular [NADH] and thus metabolic activity within activated sludge systems. Separating extracellular from intracellular [NADH] in samples was crucial because NADH was released and accumulates in the extracellular environment at a concentration of 200 ~M immediately following bacterial death or lysis. This concentration did not decline overtime. This not only caused high background fluorescence but also reduced the sensitivity of detection for changes in intracellular [NADH]. In particular, considerably higher [NADH] values to those from the extracellular suspensions were obtained following extraction of the intracellular material, suggesting that the cell membranes were not being penetrated by the excitable light source. Of the extraction procedures examined, filtration followed by extraction of the intracellular material with a hot Tris buffer was the most efficient and was recommended for accurate estimates of intracellular [NADH] in situ. In addition, standards were used to quantify NADH (moles per cell and/or unit volume) from unknown samples. The limits of detection were found to be 1.058 - 353 uM, whereas concentrations above 353 jAM self-quenched. Sample concentrations were always within these limits of detection. Hence, the sensitivity, reliability and experimental application of the original method was improved upon and able to be used for the direct measurement of microbial metabolic activity, something that has not been demonstrated before now. This study found that bacteria have between 106~ I 08 NADH molecules per cell depending on their metabolic state. A highly metabolically active bacterial cell had between 1O6~ tO7 NADH molecules, while a less active bacterial cell had between to7 -to8 NADH molecules. These measurements of metabolic activity were simultaneously monitored alongside other measures of bacterial growth, such as the incorporation of radiolabelled thymidine into DNA as a direct measure of DNA replication (new cell synthesis), the incorporation of radiolabelled leucine into protein as a direct measure of protein synthesis, oxygen uptake rates (OUR) as a direct measure of respiration, ATP as a measure of potential energy and dissolved organic carbon (DOC) as a measure of substrate assimilation. As OUR deceased, bacterial growth (using both the thymidine and leucine assays), specific [NADH] and specific [ATP] increased. High OUR and substrate oxidation rates simultaneous with low specific [NADH] indicated high rates of electron transport and thus efficient metabolic activity. Also, low OUR and substrate oxidation rates simultaneous with high specific [NADHI indicated inefficient rates of electron transport, therefore inhibiting oxidative phosphorylation (ATP production). A lack of oxygen as the terminal electron acceptor did not efficiently reoxidise NADH to NAD and resulted in an accumulation of NADH within the cell. Thus, a measure of low specific [NADHI was linked to the efficient rate of reoxidation of NADH to NAD* and reflects high metabolic efficiency. DNA and protein syntheses were coupled following substrate enrichment (glucose or acetate), indicating that bacteria were in balanced growth. However, DNA and protein syntheses became uncoupled once substrate was depleted, indicating unbalanced growth. An average Leu:TdR ratio of 7.4 was determined for activated sludge and was comparable to values published from marine systems. This ratio increased during log growth phase and decreased during stationary growth phases. Specific growth rates determined using the [3HITdR and [3H]Leu assay yielded values ranging from 2 - 10.5 d' and from 2.5 - 6 d1, respectively and were comparable to published values. Changes in OUR, NADH, ATE', DNA replication and protein synthesis were statistically ordinated using multidimensional scaling, and changes (in magnitude and direction) in bacterial metabolic activity were observed. Such methods enable the tracing of where bacteria divert their energies, such as to growth or maintenance and thus provide a greater understanding of bacterial behaviour in activated sludge. While studying anoxic and anaerobic conditions were beyond the scope of this work, the use of such methods to monitor bacterial metabolic activity under such conditions is warranted.
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Wos, Melissa Louise. "Methods For Understanding Bacterial Metabolic Activity In Activated Sludge." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/367303.
Full textAbstract:
Biological wastewater treatment relies on the diverse and complex metabolic activities of bacteria to remove pollutants. Its success depends on the metabolic efficiency of the bacteria. Activated sludge models use parameters that attempt to depict bacterial growth and metabolic processes. However, current methods do not separate metabolic activity from growth and maintenance. As a result, activated sludge processes are misinterpreted or over-simplified. Alternative methods for gauging bacterial activity have been proposed and include the measurements of cellular derived compounds that relate specifically to energy cycling and include Nicotinamide Adenine Dinucleotide [NADH]. To date, NADH has been largely measured within activated sludge using commercial online fluorimeters with in situ probes. However, this current method provides a measure of the 'bulk' (raw) fluorescence within the system, resulting in difficulties when interpreting fluorescence data and poor sensitivity for detecting changes in intracellular [NADH]. This study has developed a more reliable method for estimating intracellular [NADH] and thus metabolic activity within activated sludge systems. Separating extracellular from intracellular [NADH] in samples was crucial because NADH was released and accumulates in the extracellular environment at a concentration of 200 ~M immediately following bacterial death or lysis. This concentration did not decline overtime. This not only caused high background fluorescence but also reduced the sensitivity of detection for changes in intracellular [NADH]. In particular, considerably higher [NADH] values to those from the extracellular suspensions were obtained following extraction of the intracellular material, suggesting that the cell membranes were not being penetrated by the excitable light source. Of the extraction procedures examined, filtration followed by extraction of the intracellular material with a hot Tris buffer was the most efficient and was recommended for accurate estimates of intracellular [NADH] in situ. In addition, standards were used to quantify NADH (moles per cell and/or unit volume) from unknown samples. The limits of detection were found to be 1.058 - 353 uM, whereas concentrations above 353 jAM self-quenched. Sample concentrations were always within these limits of detection. Hence, the sensitivity, reliability and experimental application of the original method was improved upon and able to be used for the direct measurement of microbial metabolic activity, something that has not been demonstrated before now. This study found that bacteria have between 106~ I 08 NADH molecules per cell depending on their metabolic state. A highly metabolically active bacterial cell had between 1O6~ tO7 NADH molecules, while a less active bacterial cell had between to7 -to8 NADH molecules. These measurements of metabolic activity were simultaneously monitored alongside other measures of bacterial growth, such as the incorporation of radiolabelled thymidine into DNA as a direct measure of DNA replication (new cell synthesis), the incorporation of radiolabelled leucine into protein as a direct measure of protein synthesis, oxygen uptake rates (OUR) as a direct measure of respiration, ATP as a measure of potential energy and dissolved organic carbon (DOC) as a measure of substrate assimilation. As OUR deceased, bacterial growth (using both the thymidine and leucine assays), specific [NADH] and specific [ATP] increased. High OUR and substrate oxidation rates simultaneous with low specific [NADH] indicated high rates of electron transport and thus efficient metabolic activity. Also, low OUR and substrate oxidation rates simultaneous with high specific [NADHI indicated inefficient rates of electron transport, therefore inhibiting oxidative phosphorylation (ATP production). A lack of oxygen as the terminal electron acceptor did not efficiently reoxidise NADH to NAD and resulted in an accumulation of NADH within the cell. Thus, a measure of low specific [NADHI was linked to the efficient rate of reoxidation of NADH to NAD* and reflects high metabolic efficiency. DNA and protein syntheses were coupled following substrate enrichment (glucose or acetate), indicating that bacteria were in balanced growth. However, DNA and protein syntheses became uncoupled once substrate was depleted, indicating unbalanced growth. An average Leu:TdR ratio of 7.4 was determined for activated sludge and was comparable to values published from marine systems. This ratio increased during log growth phase and decreased during stationary growth phases. Specific growth rates determined using the [3HITdR and [3H]Leu assay yielded values ranging from 2 - 10.5 d' and from 2.5 - 6 d1, respectively and were comparable to published values. Changes in OUR, NADH, ATE', DNA replication and protein synthesis were statistically ordinated using multidimensional scaling, and changes (in magnitude and direction) in bacterial metabolic activity were observed. Such methods enable the tracing of where bacteria divert their energies, such as to growth or maintenance and thus provide a greater understanding of bacterial behaviour in activated sludge. While studying anoxic and anaerobic conditions were beyond the scope of this work, the use of such methods to monitor bacterial metabolic activity under such conditions is warranted.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environmental Engineering
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Aguirre, Arturo Leonardo. "Investigating quinazoline-2,4-dione and fluoroquinolone scaffolds for antibiotic activity and metabolic stability." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/6904.
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Fluoroquinolones are a class of antibiotics used clinically to treat a wide array of bacterial infections. These therapeutics act by targeting a bacterial enzyme required for cell viability, bacterial type-II topoisomerases. Fluoroquinolones act by forming a ternary complex with bacterial type II topoisomerases and cleaved DNA; religation of DNA is subsequently blocked, therefore leading to bacterial cell death. In ternary complex the keto-acid moiety of the fluoroquinolone is complexed with a divalent magnesium ion, forming a drug-magnesium-water bridge to a serine and an aspartate (or glutamate) residue on helix-4 of the topoisomerase enzyme. A major issue with fluoroquinolones is the rise in bacterial resistance. Resistance arises through substitutions of the serine or aspartate/glutamate residue, therefore preventing formation of the magnesium-water bridge and dramatically diminishing the overall antibiotic activity of the fluoroquinolone.
Quinazoline-2,4-diones are structurally similar to fluoroquinolones; diones also form a ternary complex similar to fluoroquinolones, however, these complexes are less active due to lack of a potent magnesium-water bridge interaction in helix-4. While quinazoline-2,4-diones are therefore less potent antibiotics, their non-reliance on the magnesium water bridge generally affords equipotent activity with wild-type and fluoroquinolone-resistant strains of bacteria.
The first objective of this work was to probe the helix-4 interaction of the bacterial type-II topoisomerase by quinazoline-2,4-dione modification, specifically at the N3 and C4 positions of the quinazoline-2,4-dione scaffold to afford potentially new binding contacts. These modified quinazoline-2,4-diones will provide deeper understanding of the helix-4 interaction and potentially afford potent novel quinazoline-2,4-dione scaffolds, against both wild-type and resistant bacteria, for iterative drug design.
Metabolism is one of the primary sources of detoxification, inactivation, and clearance of drugs from the body and is a critical consideration for all early stage therapeutic development. Clinically used fluoroquinolones, i.e. Moxifloxacin and Ciprofloxacin, historically are metabolically stable, and are not known to be metabolized by Phase I and/or Phase II drug metabolizing enzymes. However, major modifications to the Moxifloxacin and Ciprofloxacin scaffolds, due to the development of next generation antibiotics, may display different metabolic stability profiles. Moreover, metabolism of quinazoline-2,4-diones, developed for fluoroquinolone-resistant bacteria, is not extensively studied and may be subject to different metabolic liabilities that may render the quinazoline-2,4-dione an ineffective potential antibiotic.
The second objective of this work was to determine the in vitro Phase I and Phase II metabolic stabilities of fluoroquinolone and quinazoline-2,4-dione scaffolds to determine any structural features that render the potential therapeutic a metabolic liability.
The results from these two objectives have led to the discovery of a novel bacterial type-II topoisomerase catalytic inhibitor and the acquisition of initial metabolic stability data of fluoroquinolone and quinazoline-2,4-dione scaffolds. These findings further promote research into quinazoline-2,4-diones as bacterial topoisomerase targets, and provide metabolic considerations for both fluoroquinolone and quinazoline-2,4-dione therapeutic development, which is severely underrepresented in the field of quinolone antibiotics.
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Winkler, Jonathan Alexander. "Improving antibiotic activity by manipulating bacterial reactive oxygen species metabolism." Thesis, Boston University, 2012. https://hdl.handle.net/2144/12675.
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Thesis (Ph.D.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.The discovery of antibiotics was one of the most important medical breakthroughs of the twentieth century, having a broad impact on overall life expectancy and public health. Unfortunately, antibiotic discovery has slowed significantly in recent times and has failed to match the rising incidence of antibiotic-resistant pathogens. Gram-negative pathogens are a particularly troublesome threat, primarily because these bacteria possess an outer membrane that prevents many antibiotics from accessing their primary cellular targets. While the discovery of novel antibiotics could help to address these issues, alternative strategies, such as improving the activity of preexisting antibiotics, are also needed. Bactericidal antibiotics have recently been shown to share a common mechanism of cell death, despite having different primary, cellular targets. This shared mechanism involves the metabolic production of reactive oxygen species (ROS), which can damage proteins, lipids, and nucleic acids, and can ultimately result in bacterial cell death. The body of work described here shows that this common mechanism can be exploited to improve antibiotic activity, regardless of the antibiotic's primary mode of action. First, I will describe how bacterial metabolism can be predictably perturbed to increase endogenous ROS production, and that increasing endogenous ROS is sufficient to enhance bacterial sensitivity to treatments with ROS-generating biocides, antibiotics, and immune cell attack. I will then describe work indicating that an ancient antimicrobial agent, silver salts, can also increase endogenous ROS production and potentiate the activity of multiple antibiotic classes. Furthermore, I show that silver salts can increase the outer membrane permeability of a Gram-negative organism. This property is exploited to enable vancomycin, an antibiotic that is specific for Gram-positive bacteria, to work against a Gram-negative organism. Together, this body of work demonstrates that bacterial ROS metabolism can be exploited effectively to enhance. antibiotic activity, which ultimately could result in the discovery and development of novel antimicrobial agents.
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Muttray, Annette Friederike. "Population and metabolic activity dynamics of resin-acid-degrading bacteria as determined by the RNA, DNA ratio." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61150.pdf.
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Stadie, Jasmin [Verfasser], Rudi F. [Akademischer Betreuer] Vogel, and Siegfried [Akademischer Betreuer] Scherer. "Metabolic activity and symbiotic interaction of bacteria and yeasts in water kefir / Jasmin Stadie. Gutachter: Rudi F. Vogel ; Siegfried Scherer. Betreuer: Rudi F. Vogel." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1046939858/34.
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Tzimorotas, Dimitrios. "In vitro fermentation of various substrates by human faecal bacteria : Evaluation of type and dose of substrates as factors affecting faecal microbiota changes and metabolic activity." Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529948.
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Fougy, Lysiane. "Les impacts de la réduction de la teneur en sel sur la conservation et les écosystèmes bactériens des chipolatas." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLA039/document.
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Le sel joue un rôle essentiel dans la conservation des produits de charcuterie puisqu’il inhibe le développement bactérien. Or les recommandations nutritionnelles visent à réduire les teneurs en sel dans les denrées alimentaires. Les objectifs de ce projet de thèse étaient (1) de caractériser la communauté bactérienne des chipolatas et le phénomène d’altération sous l’effet d’une réduction de sel et (2) de corréler la dégradation organoleptique des produits aux modifications de la communauté bactérienne.Nous avons tout d’abord caractérisé l’altération des chipolatas par des mesures sensorielles et physico-chimiques. Les travaux démontrent que l’intensité de l’altération est plus importante quand la teneur en sel est réduite et plus particulièrement lorsque les chipolatas sont conditionnées sous atmosphère modifiée. L’altération est caractérisée par la production d’odeurs soufrées, aigres et rances, une diminution du pH des chipolatas et une augmentation de la production d’exsudat.Parallèlement, nous avons décrit la diversité bactérienne des chipolatas altérées par analyse des ARNr 16S bactériens et l’abondance des espèces bactériennes a été quantifiée par qPCR. Par ces méthodes, nous avons pu distinguer la population dominante de la population sous-dominante. La baisse de sel entraine un déséquilibre d’abondance entre ces deux populations et ce déséquilibre résulte non pas de l’augmentation des espèces dominantes mais d’une diminution d’abondance des espèces sous-dominantes.Pour comprendre le rôle respectif de ces populations bactériennes, nous avons analysé leurs activités métaboliques par approche RNAseq. Les travaux montrent une forte activité métabolique des espèces sous-dominantes. Lorsque le sel est en plus faible concentration, l’expression des gènes de Serratia spp. impliqués dans la fermentation du pyruvate pour produire de l’éthanol, du CO2 et de l’acétate est plus importante. La production d’acétate par cette espèce bactérienne peut être reliée aux défauts d’altération observés (baisse de pH, production d’exsudat, odeur aigre).Ces travaux démontrent que le sel impacte la communauté bactérienne des chipolatas (abondance et activités métaboliques) et que cette perturbation compromet la qualité organoleptique des produitsSalt content plays a key role in meat product preservation since it inhibits bacterial growth. However, dietary guidelines aim to reduce salt content in food. The objectives of this study were (1) to characterize the bacterial community of raw pork sausages and the spoilage phenomenon of these products under salt reduction conditions and (2) to correlate the organoleptic deterioration of the products to modifications in bacterial community.We first characterized the raw pork sausages spoilage by sensory and physicochemical analysis. The work demonstrates that spoilage intensity is greater under a reduced salt content, particularly when sausages are packaged under modified atmosphere. The spoilage is characterized by the production of sulfur, sour and rancid off-odors, a decrease in pH of the sausages and an increase of exudate production.At the same time, we described the bacterial diversity of spoiled sausages through 16S rRNA analysis. Abundance of bacterial species was quantified by qPCR. With these methods, we were able to distinguish the dominant population from the subdominant population. Reducing salt content causes an abundance imbalance between these two populations. This imbalance does not result from an increase of the dominant species; it results from a decrease in abundance of subdominant species.To understand the roles of these bacterial populations, we analyzed their metabolic activities by RNA-Seq approach. The works highlight a high metabolic activity of the subdominant species. When the salt concentration is lowest, the expression of Serratia sp. genes involved in the fermentation of pyruvate to produce ethanol, CO2 and acetate is most important. The acetate production may be connected to the spoilage defaults observed (decrease in pH, exudate production and sour off-odors).These studies reveal that salt reduction impacts the bacterial community of raw pork sausages (abundance and metabolic activities) and this disruption compromises the organoleptic quality of the products
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Diawara, Bréhima. "Conservation de riz-paddy sous atmospheres controlees : aspects microbiologiques et consequences technologiques." Nantes, 1988. http://www.theses.fr/1988NANT2016.
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Des experiences realisees sur grains stockes en cellules etanches a differentes activites d'eau ont permis de montrer qu'il est inutile de creer une atmosphere anoxique artificielle pour stabiliser les populations microbiennes naturelles. Une relation quantitative directe existe entre croissance, sporulation et quantite d'oxygene disponible dans l'ecosysteme. Aux tres faibles pressions partielles d'oxygene, la perte de viabilite des propagules fongiques est fonction de l'activite d'eau des grains. Les qualites technologiques des grains restent stables pour les activites d'eau inferieures a 0. 95. Seules les levures de stockage sont capables de se developper dans ces conditions gazeuses, des lors que l'activite d'eau est superieure ou egale a 0. 86. Le developpement particulier d'hyphopichia burtonii (boidin) en presence de traces d'oxygene et l'arret de sa croissance en anaerobiose stricte montrent que c'est une espece "microaerotolerante". En presence de traces d'oxygene, le dioxyde de carbone a un effet stabilisant sur les populations fongiques (aspergillus, penicillium). Cependant, le dioxyde de carbone employe seul ne saurait assurer la stabilite microbiologique des grains conserves en structures insuffisamment etanches
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Barsotti, Vanessa. "Recherche et caractérisation de microorganismes dans les compartiments géologiques profonds." Phd thesis, Bordeaux 1, 2011. http://tel.archives-ouvertes.fr/tel-00688631.
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Les compartiments géologiques profonds suscitent un intérêt grandissant dans la communauté scientifique depuis les 50 dernières années. Néanmoins, ces écosystèmes demeurent largement méconnus du fait de leur difficulté d'accès. Le forage profond réalisé par l'ANDRA dans le Bassin parisien en 2008 a offert une opportunité unique de les étudier. Dans ce cadre, cette thèse avait deux objectifs majeurs ; i) caractériser, d'un point de vue microbiologique, quatre formations sédimentaires terrestres triasiques situées entre 1700 et 2000 m de profondeur et ii) étudier les effets combinés des paramètres de température, pression et salinité ainsi que de leur interaction sur l'activité métabolique de procaryotes anaérobies afin de mieux appréhender leur comportement au cours d'un enfouissement géologique.Malgré la recherche de microorganisme par la réalisation d'une gamme de milieux de culture diversifiée, ciblant préférentiellement les types trophiques fréquemment rencontrés en subsurface (méthanogènes, fermentaires, réducteurs de composés soufrés), aucun microorganisme viable et cultivable n'ait été isolé. En parallèle, une approche moléculaire complémentaire, composée (i) de l'étude comparative de l'efficacité de différentes méthodes d'extraction directe d'ADN et (ii) de l'analyse de la diversité bactérienne par la réalisation d'inventaires moléculaires, par DGGE (Denaturing Gel Gradient Electrophoresis) et clonage, a été réalisée sur le coeur des carottes de roches, conservées à pression atmosphérique ou sous pression, dans leurs états initiaux et post-incubation. L'exploration de ces formations sédimentaires profondes a indiqué la présence d'une très faible biomasse et d'une biodiversité microbienne pauvre principalement composée de membres aérobies et mésophiles appartenant au domaine Bacteria. Cette communauté bactérienne inattendue car a priori peu adaptée aux conditions régnant in-situ, également retrouvée dans divers écosystèmes de subsurface ainsi que dans des biotopes extrêmes, pourrait provenir en partie d'une paléo-recharge de l'aquifère du Trias par des eaux froides dérivées de la fonte des glaces formées lors de la dernière glaciation du Pléistocène.Le second objectif a été abordé à travers l'élaboration d'un plan factoriel complet dans le but d'identifier les effets des paramètres sur les activités microbiennes. Ainsi, les activités métaboliques de huit souches microbiennes halophiles et thermo-tolérantes ont été mesurées sous trente conditions distinctes de température (40, 55 et 70°C), pression (1, 90 et 180 bars) et salinité (13, 50, 110, 180 et 260 g.l-1). Toutes les souches originaires d'environnements profonds se sont révélées être au minimum piézo-tolérantes et capables de maintenir leur activité métabolique sous pressions hydrostatiques. Les métabolismes fermentaires (Thermovirga lienii et Halothermothrix orenii) et thiosulfato-réducteurs (Petrotoga mexicana et Thermosipho japonicus) se sont avérés particulièrement bien adaptées, d'un point de vue métabolique, aux hautes pressions, les plus hautes activités ayant été détectées sous pression. Certaines souches ont montré une résistance accrue aux hautes températures sous pression (Petrotoga mexicana). Toutefois une résistance variable à la salinité dans les différentes conditions de température et de pression a été observée pour chacune des souches, suggérant que certains mécanismes de résistance contre la pression osmotique seraient également efficaces pour lutter contre les températures et les pressions hydrostatiques élevées.Ce travail souligne que l'étude des écosystèmes terrestres profonds d'un point de vue microbiologique ne doit pas se restreindre à la recherche et à l'analyse de la diversité présente. L'étude des activités métaboliques de souches de subsurface en conditions profondes ouvre la voie à une meilleure compréhension des rôles joués par les communautés microbiennes en milieu extrême.
Books on the topic "Bacterial metabolic activity"
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Main, Fiona Gillian. The use of fluorescein diacetate and carboxy-fluorescein diacetate to analyse metabolic activity in oral bacteria using the flow cytometer. Ottawa: National Library of Canada, 1990.
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Money, Nicholas P. 1. Microbial diversity. Oxford University Press, 2014. http://dx.doi.org/10.1093/actrade/9780199681686.003.0001.
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‘Microbial diversity’ considers the vast array of microorganisms—the smallest forms of life—which exist everywhere. The three primary groups of microorganisms are bacteria, archaea, and eukaryotes. Bacteria and archaea are prokaryotes with their genetic material held in a single chromosome. In eukaryotes, most of the genome is held in multiple chromosomes. Over 11,000 species of bacteria have been identified using microscopic identification of cell shape and metabolic activity, Gram-staining techniques, and genetic identification of RNA and DNA sequences. There are 500 named species of archaea, divided into two phyla: the euryarchaeota and the crenarchaeota. There are eight supergroupings of eukaryotes, all of them include single-celled organisms, and five are entirely microbial.
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1935-, Tipper Donald J., ed. Antibiotic inhibitorsof bacterial cell wall biosynthesis. Oxford: Pergamon, 1987.
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1935-, Tipper Donald J., ed. Antibiotic inhibitors of bacterial cell wall biosynthesis. Oxford [Oxfordshire]: Pergamon Press, 1987.
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Hilbert, Scott Allen. Use of ribosomal RNA content as an indicator of the metabolic activity of suspended and attached bacteria. 1993.
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Kirchman, David L. Degradation of organic matter. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0007.
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The aerobic oxidation of organic material by microbes is the focus of this chapter. Microbes account for about 50% of primary production in the biosphere, but they probably account for more than 50% of organic material oxidization and respiration (oxygen use). The traditional role of microbes is to degrade organic material and to release plant nutrients such as phosphate and ammonium as well as carbon dioxide. Microbes are responsible for more than half of soil respiration, while size fractionation experiments show that bacteria are also responsible for about half of respiration in aquatic habitats. In soils, both fungi and bacteria are important, with relative abundances and activity varying with soil type. In contrast, fungi are not common in the oceans and lakes, where they are out-competed by bacteria with their small cell size. Dead organic material, detritus, used by microbes, comes from dead plants and waste products from herbivores. It and associated microbes can be eaten by many eukaryotic organisms, forming a detritus food web. These large organisms also break up detritus into small pieces, creating more surface area on which microbes can act. Microbes in turn need to use extracellular enzymes to hydrolyze large molecular weight compounds, which releases small compounds that can be transported into cells. Fungi and bacteria use a different mechanism, “oxidative decomposition,” to degrade lignin. Organic compounds that are otherwise easily degraded (“labile”) may resist decomposition if absorbed to surfaces or surrounded by refractory organic material. Addition of labile compounds can stimulate or “prime” the degradation of other organic material. Microbes also produce organic compounds, some eventually resisting degradation for thousands of years, and contributing substantially to soil organic material in terrestrial environments and dissolved organic material in aquatic ones. The relationship between community diversity and a biochemical process depends on the metabolic redundancy among members of the microbial community. This redundancy may provide “ecological insurance” and ensure the continuation of key biogeochemical processes when environmental conditions change.
Book chapters on the topic "Bacterial metabolic activity"
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Jutras, Philippe V., Isobel Dodds, and Renier A. L. van der Hoorn. "A Bioluminescent Agrobacterium tumefaciens for Imaging Bacterial Metabolic Activity in Planta." In Recombinant Proteins in Plants, 285–93. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2241-4_15.
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Bonnichsen, Lise, Nanna Bygvraa Svenningsen, Mette Haubjerg Nicolaisen, and Ole Nybroe. "Methods to Determine Bacterial Abundance, Localization, and General Metabolic Activity in Soil." In Modern Soil Microbiology, 195–213. Third edition. | Boca Raton : Taylor & Francis, 2019.: CRC Press, 2019. http://dx.doi.org/10.1201/9780429059186-12.
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Takano, T. "Anti-hypertensive activity of fermented dairy products containing biogenic peptides." In Lactic Acid Bacteria: Genetics, Metabolism and Applications, 333–40. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-017-2029-8_22.
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Tanous, Catherine, Agnieszka Kieronczyk, Sandra Helinck, Emilie Chambellon, and Mireille Yvon. "Glutamate dehydrogenase activity: a major criterion for the selection of flavour-producing lactic acid bacteria strains." In Lactic Acid Bacteria: Genetics, Metabolism and Applications, 271–78. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-017-2029-8_17.
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S. Nair, Sneha, Prabha Susan Philip, and K. S. Karthika. "Soil Bacteria- Our Allies in Building Soil Health." In Industrial Applications of Soil Microbes, 1–38. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815039955122010005.
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Microorganisms give life to the soil and provide a variety of ecosystem services to plants. Soil bacteria are the strongest candidates for determining soil health. Bacterial communities are important for the health and productivity of soil ecosystems. Therefore, we must have a thorough knowledge of the diversity, habitat, and ecosystem functioning of bacteria. In this chapter, we will discuss the functional, metabolic, and phylogenetic diversity of soil bacteria and highlight the role of bacteria in the cycling of major biological elements (C, N, P, and S), detoxification of common soil pollutants, disease suppression, and soil aggregation. This chapter also underlines the use of soil bacteria as indicators of soil health. We have concluded the chapter by taking note of the present agricultural practices that call for concern regarding the natural soil microflora and steps to return biological activity to the soil.
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Paley, Elena L., Tatiana Merkulova-Rainon, Aleksandr Faynboym, Valery I. Shestopalov, and Igor Aksenoff. "Geographical Distribution and Diversity of Gut Microbial NADH: Ubiquinone Oxidoreductase Sequence Associated with Alzheimer’s Disease." In Advances in Alzheimer’s Disease. IOS Press, 2022. http://dx.doi.org/10.3233/aiad220019.
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Earlier we reported induction of neurotoxicity and neurodegeneration by tryptophan metabolites that link the metabolic alterations to Alzheimer’s disease (AD). Tryptophan is a product of the Shikimate pathway (SP). Human cells lack SP, which is found in human gut bacteria exclusively using SP to produce aromatic amino acids (AAA). This study is a first attempt toward gene-targeted analysis of human gut microbiota in AD fecal samples. The oligonucleotide primers newly-designed for this work target SP-AAA in environmental bacteria associated with human activity. Using polymerase chain reaction (PCR), we found unique gut bacterial sequence in most AD patients (18 of 20), albeit rarely in controls (1 of 13). Cloning and sequencing AD-associated PCR products (ADPP) enables identification of Na(+)-transporting NADH: Ubiquinone reductase (NQR) in Clostridium sp. The ADPP of unrelated AD patients possess near identical sequences. NQR substrate, ubiquinone is a SP product and human neuroprotectant. A defici in ubiquinone has been determined in a number of neuromuscular and neurodegenerative disorders. Antibacterial therapy prompted an ADPP reduction in an ADPP-positive control person who was later diagnosed with AD-dementia. We explored the gut microbiome databases and uncovered a sequence similarity (up to 97%) between ADPP and some healthy individuals from different geographical locations. Importantly, our main findin of the significan difference in the gut microbial genotypes between the AD and control human populations is a breakthrough.
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Thakur, Kiran, Jian Guo Zhang, Zhao-Jun Wei, Narendra Kumar, Sudhir Kumar Tomar, and Sarang Dilip Pophaly. "Cross Talk Between Functional Foods and Gut Health." In Complementary and Alternative Medicine, 330–51. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7039-4.ch014.
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The phrase “Let food be the medicine and medicine be the food,” coined by Hippocrates over 2500 years ago is receiving a lot of interest today as food scientists and consumers realize the many health benefits of certain foods. Lately, consumer's choice in food consumption has improved considerably due to the acknowledgment of the fact that foods influence the overall human health. There has been a growing interest over the years to explore beneficial gut microbiota and different interventions are devised to modulate the microbiota through the use of probiotics, prebiotics and synbiotics. Besides improving intestinal health, functional food ingredients also have the potential to restore the gut homeostasis during intestinal disorders conditions. The human gut has a marked effect on the nutritional and health status of the host due to the presence of diverse bacterial species, which develop important metabolic and immune functions. This makes intestinal microbiota a target for nutritional and therapeutic interventions and a factor which influence the biological activity of other food compounds .This chapter attempts to highlight how the reciprocal interactions take place between the gut microbiota and functional food components and how these interactions affect human health and manage various metabolic disorders.
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Shankara S., Kotresha Dupadahalli, Vijayakumar M. H., and Gaddad S. M. "Decolorization of Direct Blue." In Advances in Environmental Engineering and Green Technologies, 279–94. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-9734-8.ch014.
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A thermo-alkalophilic bacterium isolated from textile mill effluent samples and identified as a Bacillus sp., on the basis of biochemical tests. The selected bacterium showed high decolorization activity in static condition as compared to shaking condition and the maximum 1000 mg l-1 Direct Blue-14 dye decolorization was takes place in 72 h. The optimum physical parameters such as temperature 40-50 °C, pH 8.0 with 2.5% (w/v) of nitrogen source and 4% (w/v) glucose were required for the decolorization of Direct Blue-14 from this bacterium. UV–Visible analyses and colorless bacterial cells suggested that Bacillus sp. exhibited decolorizing activity through biodegradation, rather than inactive surface adsorption. The degraded dye metabolites are analyzed by TLC and diazotization, carbylamines, Ames test for individual metabolite indicates biotransformation of Direct Blue-14 into aromatic amine and non-toxic aromatic metabolites. These results suggest that the isolated organism Bacillus sp. as a useful tool to treat waste water containing azo dyes at static condition.
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Pophaly, Sarang Dilip, Manorama Chauhan, Vaibhao Lule, Poonam Sarang, Jitesh Tarak, Kiran Thakur, and Sudhir Kumar Tomar. "Functional Starter Cultures for Fermented Dairy Products." In Microbial Cultures and Enzymes in Dairy Technology, 54–68. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5363-2.ch003.
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Fermented dairy products are known for their high nutritional and therapeutic value and are also having excellent sensory characteristics, which make them popular throughout the world. Most of the characteristics of fermented products can be attributed to the activity of their starter culture. The starter microorganisms, in the course of their metabolism, elaborate various compounds and enzymes, which impart desirable properties to the product. Lactic acid bacteria (LAB) are the most common starter bacterial group used extensively in fermentation of dairy products. Lactic acid bacteria synthesize different compounds belonging to classes of organic acids, gases, bacteriocins, flavoring agents, biothickners, nutrients, etc. Molecules within each class vary for each species and even within strains. The functionalities from such novel starter cultures include improved nutritional value, sensory characteristics, and therapeutic benefits. These starter cultures are thus important for development of functional fermented and probiotic products. This chapter explores functional starter cultures for fermented dairy products.
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Bahadoran, Zahra, Pedro González-Muniesa, Parvin Mirmiran, and Asghar Ghasemi. "Nitric Oxide-Related Oral Microbiota Dysbiosis in Type 2 Diabetes." In The Role of Nitric Oxide in Type 2 Diabetes, 87–106. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815079814122010008.
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The nitrate (NO3)-nitrite (NO2)-nitric oxide (NO) pathway, as a storage reservoir for endogenous NO production, is dependent on the oral bacteria with NO3- reducing capacity. Undesirable changes of oral microbiota towards a decreased load of health-related NO3-reducing bacteria and an overgrowth of pathogenic species, leading to subsequent decreased NO2 production in the oral cavity and decreased systemic NO availability, are now considered risk factors for the development of insulin resistance and type 2 diabetes (T2D). This chapter discusses available evidence focusing on oral microbiota dysbiosis in T2D, especially NO3-reducing bacteria and their metabolic activity (including NO3-reductase and NO2-reductase activity), affecting net oral NO2 accumulation and the NO3-NO2-NO pathway.
Conference papers on the topic "Bacterial metabolic activity"
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Ortega-Tenezaca, Bernabe. "Mapping Bacterial Metabolic Network topology vs. Nanoparticle antibacterial activity." In MOL2NET'21, Conference on Molecular, Biomedical & Computational Sciences and Engineering, 7th ed. Basel, Switzerland: MDPI, 2021. http://dx.doi.org/10.3390/mol2net-07-11832.
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Terzić, Jelena, Marina Stanković, and Olgica Stefanović. "ANTIBIOFILM ACTIVITY OF SELECTED PLANT SPECIES." In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.280t.
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Bacterial biofilm is a complex community of bacterial cells enclosed in a polymer matrix and attached to a biotic or abiotic substrate. In this living form the bacteria are more resistant to antimicrobial agents than in the form of planktonic cells. Biofilm is a common cause of chronic infections in humans, so due to the growing resistance to antibiotics, alternative methods for controlling infections using medicinal plants have been proposed. In this study, the antibiofilm activity of ethanol and acetone extracts of plants Lamium album, Achillea millefolium and Agrimonia eupatoria against eight clinical isolates of human pathogenic bacteria was examined. Inhibition of biofilm formation was demonstrated using the crystal violet test and the effect on metabolic activity was confirmed by the use of resazurin dye test. Ethanol extract of L. album showed the greatest activity against P. aeruginosa (PA9) at a concentration of 20 mg/ml (> 80% of inhibition), while acetone extract acted at a concentration of 5 mg/ml (≥ 18%) against Klebsiella sp. (K9). At a concentration of 10 mg/ml, the ethanol extract of A. millefolium was effective against E. coli (E16) and P. aeruginosa (PA8) (> 70%), while the acetone extract was effective at 2.5 mg/ml (> 80%) against E. coli (E16). Ethanol and acetone extracts of A. eupatoria were effective at a concentration of 10 mg/ml (> 50%) against E. coli (E16). The antibiofilm activity of the tested plant extracts on certain clinical isolates indicates their great potential in the treatment of infections caused by biofilm-producing bacteria.
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Peysepar, Mahyar, Mohammad Behshad Shafii, Ramin Rasoulian, Hosein Jamalifar, and Mohammad Reza Fazeli. "Use of the Freely-Swimming, Serratia Marcescens Bacteria to Enhance Mixing in Microfluidic Systems." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11469.
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Mixing has become a challenge in micro-fluidic systems because of the low Reynolds number in micro-channels. The method which is implemented in this paper is to use freely-swimming bacteria to enhance the mixing process. Accordingly, the Serratia marcescens bacteria were used for this matter. The mixing performance of the system is quantified by measuring the diffusion rate of Rhodamine B in a particular section of a channel connected to a chamber with varying Rhodamine B concentration. The concentration of Rhodamine B was measured using the Laser Induced Fluorescence (LIF) technique. The channel is in the form of a pipe and is closed on the extending side. In this paper, it is demonstrated that the corresponding diffusion coefficient can be augmented by bacterial participation and that this augmentation can be continued for several hours, depending on the environmental conditions. Additionally, it is shown that the mixing process reacts in response to modifications to the chemical environment of the system, which in turn affect the metabolic activity of the bacteria. Also, a 30 mM glucose buffer was used to show the impact of food on the performance of the bacterial system. It is thus shown that the existence of glucose increases the mixing ability of bacteria.
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Garcia, Alfonso, Trevor Place, Michael Holm, Jennifer Sargent, and Andrew Oliver. "Pipeline Sludge Sampling for Assessing Internal Corrosion Threat." In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33113.
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Internal corrosion sometimes occurs under deposits of solid particles on the bottom of transmission pipelines. The solids trap water with soluble products and other nutrients which can support the development of microbial communities and may lead to Microbiologically Influenced Corrosion (MIC). Corrosion processes associated with the metabolic activities of specific bacteria have been discussed elsewhere, but the simple presence of large microbial populations may increase the risk of internal corrosion owing to the ability of biofilms to extract and concentrate water at the pipe floor. As a method to monitor the internal corrosion threat in transmission pipelines and recommend mitigating activities for corrosion management, reliable microbial content and corrosion activity correlations are desired. Sludge samples have been obtained from cleaning pigs at the pipe trap and analyzed using Biological Activity Reaction Test (BART™) (or serial dilution test), Dean-Stark analysis, XRD and EDX. These tests provide information about certain bacterial populations, water / solid / hydrocarbon content, and crystalline/elemental composition of these solids, respectively. Despite best efforts, bacterial population/activity of pipeline sludge samples exhibit high variability and are difficult to correlate to actual internal corrosion in a pipeline. Considering that bacterial populations in pipeline sludge may be a meaningful representation of the internal corrosion threat to a transmission pipeline, a more rigorous approach on the sludge sampling procedure is necessary to improve the accuracy and reliability of the bacterial assays. It is also important to control such variables as storage temperature of the samples, exposure to air, and storage duration prior to enumeration — as these may affect the viability of the sample and enumeration results. This report presents historical pipeline sludge analysis data and suggests a method to evaluate data containing high variability. Practical recommendations to reduce data variability through handling and storage of sludge samples are also discussed.
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Sultana, Sharmin, Md Sad Salabi Sawrav, Snygdha Rani Das, Mehfuz Alam, Md Abdul Aziz, Md Al-Amin Hossain, and Md Azizul Haque. "Isolation and Biochemical Characterization of Cellulase Producing Goat Rumen Bacteria." In International Conference on Emerging Trends in Engineering and Advanced Science. AIJR Publisher, 2022. http://dx.doi.org/10.21467/proceedings.123.12.
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Cellulose is the most prevalent polymer on the planet and has long been utilized for a variety of industrial applications. The study's goal was to screen and isolate cellulase-producing bacteria from the rumen of a goat collected from different location of Dinajpur district. To do so, rumen content samples from two distinct goats were collected. In this investigation, rumen cellulase-producing bacteria were isolated and characterized after serial dilution of five isolates up to six fold and inoculation into Nutrient agar. Following that, all of the isolates were underwent Methyl Red (MR) test & Voges-Proskauer (VP) test to identify organism’s metabolic pathway, Triple Sugar Iron Agar (TSI) Test to determine bacterial ability to utilize sugar, Motility Indole and Urease activity test (MIU) to determine motility, Urease utilization and can produce Indole or not, Citrate utilization test to utilize citrate as carbon and energy source, Oxidase test, Catalase test to check the presence of catalytic enzyme. The result revealed the colonial characterization of bacteria and also where proven all five isolates are promising enough and superior in quality to produce cellulose.
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Alsakkaf, Sarah, Sahar Al-Dosary, Hesham El-Komy, and Mona Al. Ahmadi. "Effect of Different Nanoparticles Silver, Iron Oxide and Titanium Oxide to Control Corrosion by Desulfovibrio Sp.Isolated from Oil Fields." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22588-ms.
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Abstract Microbiologically influenced corrosion (MIC), or biocorrosion is a corrosion of metals in environment containing microorganism. The microorganisms can initiate corrosion or accelerate by their metabolic activities. Recently, MIC problems common in oil recovery which depend on seawater injection. Many of researchers have been investigated that Sulfate-reducing bacteria (SRB) is the major groups of microorganisms that cause corrosion. Pitting corrosion and sulfide generation in oil and gas fields are correlated to presence of SRB. Last decade, nanotechnology is alternative biocide of chlorine-free. Metal nanoparticles improve the antimicrobial activity of the metals. The biocidal activity of AgNPs, Fe2O3NPs and TiO2NPs against Desulfovibrio sp. (St.7) at 1 ppm, 50 ppm and 100 ppm concentrations as estimated by cell growth and H2S production was examined. AgNPs and Fe2O3NPs had no significant effect at a low concentration, 1 ppm, on both bacterial growth and sulfide production. Whereas, increasing NPs concentration to 50 ppm and 100 ppm led to a complete inhibition of both growth and sulfide production. TiO2NPs gave complete inhibitory effect on both growth and H2S production by Desulfovibrio sp. (St.7) at all the tested concentrations (1ppm, 50ppm, 100ppm). The study supports the use of such nanoparticles as a green biocide and safe method to control corrosion problem caused by sulphate reducing bacteria.
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Sultana, Sharmin, Md Sad Salabi Sawrav, Md Bokhtiar Rahma, Md Shohorab Hossain, and Md Azizul Haque. "Isolation and Biochemical Characterization of Xylanase Enzyme Producing Bacteria from Goat Rumen." In International Conference on Emerging Trends in Engineering and Advanced Science. AIJR Publisher, 2022. http://dx.doi.org/10.21467/proceedings.123.1.
Full textAbstract:
The rumen microbial communities of ruminants are thought to be the most promising biochemical source of inordinately diversified and multi-functional cellulolytic enzymes with unique functional adaptations to improve biotechnological processes. The exploitation of rumen microbial genetic variety has been limited due to a lack of effective screening culture techniques and a lack of understanding of the rumen microbial genetic diversity. This study is conducted to isolate and characterize rumen bacteria from goat rumen that have capability to produce xylanase enzyme. Serial dilutions technique is applied to isolate bacteria from goat rumen and repeated tubing of the selectively enriched microbial cultures by using the specific media for rumen bacteria. Following that, all of the isolates were underwent Methyl Red (MR) test & Voges-Proskauer (VP) test to identify organisms metabolic pathway, Triple Sugar Iron Agar (TSI) Test to determine bacterial ability to utilize sugar, Motility Indole and Urease activity test (MIU) to determine motility, Urease utilization and can produce Indole or not, Citrate utilization test to utilize citrate as carbon and energy source, Oxidase test, Catalase test to check the presence of catalytic enzyme where all isolates found promising which indicates that all five isolates are superior and capable to produce xylanase.
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Yaprak, Elif, and Nizami Duran. "Activity of Oleic Acid on Biofilm Formation of S. aureus." In The 9th International Conference on Advanced Materials and Systems. INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania, 2022. http://dx.doi.org/10.24264/icams-2022.iii.21.
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Oleic acid is a naturally occurring fatty acid in animal and vegetable oils and has been shown to have a wide variety of pharmacological effects. It aimed to investigate the efficacy of oleic acid on the adhesion and invasion of S. aureus to the host cell and biofilm production. The standard S. aureus strain (ATCC 25923) was used in the experiments. Cytotoxicity tests of oleic acid were performed in the Vero cell line. Bacterial adhesion and invasion rates and activities on slime formation in cells treated with oleic acid were evaluated compared to the control group. Slime formation tests were evaluated phenotypically on Congo red agar. In the study, it was determined that oleic acid was effective in both cellular adhesion and invasion in terms of colony number in cell cultures treated with 0.156 µg/ml concentration of oleic acid. In addition, it was determined that slime production was significantly inhibited in bacterial cultures treated with oleic acid. Oleic acid prevents cells from attaching to bacteria and has an inhibitory effect on the virulence of bacteria. This activity of oleic acid may be due to its modulatory effect on cellular processes, and its bacterial virulence may be related to its effect on bacterial metabolism.
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Loh, Kenneth J., Jeremy S. Guest, Genevieve Ho, Jerome P. Lynch, and Nancy G. Love. "Layer-by-layer carbon nanotube bio-templates for in situ monitoring of the metabolic activity of nitrifying bacteria." In SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, edited by Tribikram Kundu. SPIE, 2009. http://dx.doi.org/10.1117/12.815995.
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Purwestri, Yekti Asih, Nur’aini Kartikasari, Sartika Gunawan Putri, Wildiani Wilson, and Langkah Sembiring. "Metabolic profiling of endophytic bacteria from Purwoceng (Pimpinella pruatjan Molkend) root and antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa." In TOWARDS THE SUSTAINABLE USE OF BIODIVERSITY IN A CHANGING ENVIRONMENT: FROM BASIC TO APPLIED RESEARCH: Proceeding of the 4th International Conference on Biological Science. Author(s), 2016. http://dx.doi.org/10.1063/1.4953537.
Full textReports on the topic "Bacterial metabolic activity"
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Jander, Georg, Gad Galili, and Yair Shachar-Hill. Genetic, Genomic and Biochemical Analysis of Arabidopsis Threonine Aldolase and Associated Molecular and Metabolic Networks. United States Department of Agriculture, January 2010. http://dx.doi.org/10.32747/2010.7696546.bard.
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Since the amino acids threonine and isoleucine can be limiting in mammalian diet and there is interest in increasing their abundance in certain crop plants. To meet this need, a BARD proposal was written with two main research objectives: (i) investigate new avenues for manipulating threonine and isoleucine content in plants and (ii) study the role of threonine aldolase in plant metabolism. Research conducted to meet these goals included analysis of the sub-cellular localization of threonine aldolase in the plant, analysis of metabolic flux in developing embryos, over- and under-expression of Arabidopsis threonine aldolases, and transcriptional and metabolic analysis of perturbations resulting from altered threonine aldolase expression. Additionally, the broader metabolic effects of increasing lysine biosynthesis were investigated. An interesting observation that came up in the course of the project is that threonine aldolase activity affects methionine gamma-lyase in Arabidopsis. Further research showed that threonine deaminase and methionine gamma-lyase both contribute to isoleucine biosynthesis in plants. Therefore, isoleucine content can be altered by manipulating the expression of either or both of these enzymes. Additionally, both enzymes contribute to the up to 100-fold increase in isoleucine that is observed in drought-stressed Arabidopsis. Toward the end of the project it was discovered that through different projects, both groups had been able to independently up-regulate phenylalanine accumulation by different mechanisms. The Galili lab transformed Arabidopsis with a feedbackinsensitive bacterial enzyme and the Jander lab found a feedback insensitive mutation in Arabidopsis arogenate dehydratase. Exchange of the respective plant lines has allowed a comparative analysis of the different methods for increasing phenylalanine content and the creation of double mutants. The research that was conducted as part of this BARD project has led to new insights into plant amino acid metabolism. Additionally, new approaches that were found to increase the accumulation of threonine, isoleucine, and phenylalanine in plants have potential practical applications. Increased threonine and isoleucine levels can increase the nutritional value of crop plants. Elevated isoleucine accumulation may increase the osmotic stress tolerance of plants. Up-regulation of phenylalanine biosynthesis can be used to increase the production of downstream higher-value plant metabolites of biofuel feed stocks.
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Cytryn, Eddie, Mark R. Liles, and Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
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Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.
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Cohen, Jerry D., and Ephraim Epstein. Metabolism of Auxins during Fruit Development and Ripening. United States Department of Agriculture, August 1995. http://dx.doi.org/10.32747/1995.7573064.bard.
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We had proposed to look at several aspects of auxin metabolism in fruit tissues: 1) IAA biosynthesis from tryptophan and IAA biosynthesis via the non-tryptophan pathway; 2) changes in the capacity to form conjugates and catabolites of auxin at different times during fruit development and; 3) the effects of modifying auxin metabolism in fruit tissues. The latter work focused primarily on the maize iaglu gene, with initial studies also using a bacterial gene for hydrolysis of IAA-aspartate. These metabolic and molecular studies were necessary to define potential benefits of auxin metabolism modification and will direct future efforts for crop improvement by genetic methods. An in vitro system was developed for the production of tomato fruit in culture starting from immature flowers in order to ascertain the effect of auxin modification on fruit ripening. IAA supplied to the fruit culture media prior to breaker stage resulted in an increase in the time period between breaker and red-ripe stages from 7 days without additional IAA to 12 days when 10-5 M IAA was added. These results suggest that significant changes in the ripening period could be obtained by alteration of auxin relationships in tomato fruit. We generated transgenic tomato plants that express either the maize iaglu gene or reduced levels of the gene that encodes the enzyme IAA-glucose synthetase. A modified shuttle vector pBI 121 expressing the maize iaglu gene in both sense and antisense orientations under a 35S promoter was used for the study. The sense plants showed total lack of root initiation and development. The antisense transgenic plants, on the other hand, had unusually well developed root systems at early stages in development. Analysis showed that the amount and activity of the endogenous 75 kDa IAGLU protein was reduced in these plants and consequently these plants had reduced levels of IAA-glucose and lower overall esterified IAA.
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Wackett, Lawrence, Raphi Mandelbaum, and Michael Sadowsky. Bacterial Mineralization of Atrazine as a Model for Herbicide Biodegradation: Molecular and Applied Aspects. United States Department of Agriculture, January 1999. http://dx.doi.org/10.32747/1999.7695835.bard.
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Atrazine is a broadly used herbicide in agriculture and it was used here as a model to study the biodegradation of herbicides. The bacterium Pseudomonas sp. ADP metabolizes atrazine to carbon dioxide and ammonia and chloride. The genes encoding atrazine catabolism to cyanuric acid were cloned and expressed in Escherichia coli. The genes were designated atzA, atzB and atzC. Each gene was sequenced. The enzyme activities were characterized. AtzA is atrazine chlorohydrolase which takes atrazine to hydroxyatrizine. AtzB is hydroxyatrazine N-ethylaminohydrolase which produces N-isopropylammelide and N-ethylamine. AtzC is N-isopropylammelide N-isopropylaminohydrolase which produces cyanuric acid and N-isopropylamine. Each product was isolated and characterized to confirm their identity by chromatography and mass spectrometry. Sequence analysis indicated that each of the hydrolytic enzymes AtzA, AtzB and AtzC share identity which the aminohydrolase protein superfamily. Atrazine chlorohydrolase was purified to homogeneity. It was shown to have a kcat of 11 s-1 and a KM of 150 uM. It was shown to require a metal ion, either Fe(II), Mn(II) or Co(II), for activity. The atzA, atzB and atzC genes were shown to reside on a broad-host range plasmid in Pseudomonas sp. ADP. Six other recently isolated atrazine-degrading bacteria obtained from Europe and the United States contained homologs to the atz genes identified in Pseudomonas sp. ADP. The identity of the sequences were very high, being greater than 98% in all pairwise comparisons. This indicates that many atrazine-degrading bacteria worldwide metabolize atrazine via a pathway that proceeds through hydroxyatrazine, a metabolite which is non-phytotoxic and non-toxic to mammals. Enzymes were immobilized and used for degradation of atrazine in aqueous phases. The in-depth understanding of the genomics and biochemistry of the atrazine mineralization pathway enabled us to study factors affecting the prevalence of atrazine degradation in various agricultural soils under conservative and new agricultural practices. Moreover, Pseudomonas sp. ADP and/or its enzymes were added to atrazine-contaminated soils, aquifers and industrial wastewater to increase the rate and extent of atrazine biodegradation above that of untreated environments. Our studies enhance the ability to control the fate of regularly introduced pesticides in agriculture, or to reduce the environmental impact of unintentional releases.
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Choudhary, Ruplal, Victor Rodov, Punit Kohli, Elena Poverenov, John Haddock, and Moshe Shemesh. Antimicrobial functionalized nanoparticles for enhancing food safety and quality. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598156.bard.
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Original objectives The general goal of the project was to utilize the bactericidal potential of curcumin- functionalizednanostructures (CFN) for reinforcement of food safety by developing active antimicrobial food-contact surfaces. In order to reach the goal, the following secondary tasks were pursued: (a) further enhancement of the CFN activity based on understanding their mode of action; (b) preparing efficient antimicrobial surfaces, investigating and optimizing their performance; (c) testing the efficacy of the antimicrobial surfaces in real food trials. Background to the topic The project dealt with reducing microbial food spoilage and safety hazards. Cross-contamination through food-contact surfaces is one of the major safety concerns, aggravated by bacterial biofilm formation. The project implemented nanotech methods to develop novel antimicrobial food-contact materials based on natural compounds. Food-grade phenylpropanoidcurcumin was chosen as the most promising active principle for this research. Major conclusions, solutions, achievements In agreement with the original plan, the following research tasks were performed. Optimization of particles structure and composition. Three types of curcumin-functionalizednanostructures were developed and tested: liposome-type polydiacetylenenanovesicles, surface- stabilized nanoparticles and methyl-β-cyclodextrin inclusion complexes (MBCD). The three types had similar minimal inhibitory concentration but different mode of action. Nanovesicles and inclusion complexes were bactericidal while the nanoparticlesbacteriostatic. The difference might be due to different paths of curcumin penetration into bacterial cell. Enhancing the antimicrobial efficacy of CFN by photosensitization. Light exposure strengthened the bactericidal efficacy of curcumin-MBCD inclusion complexes approximately three-fold and enhanced the bacterial death on curcumin-coated plastic surfaces. Investigating the mode of action of CFN. Toxicoproteomic study revealed oxidative stress in curcumin-treated cells of E. coli. In the dark, this effect was alleviated by cellular adaptive responses. Under light, the enhanced ROS burst overrode the cellular adaptive mechanisms, disrupted the iron metabolism and synthesis of Fe-S clusters, eventually leading to cell death. Developing industrially-feasible methods of binding CFN to food-contact surfaces. CFN binding methods were developed for various substrates: covalent binding (binding nanovesicles to glass, plastic and metal), sonochemical impregnation (binding nanoparticles to plastics) and electrostatic layer-by-layer coating (binding inclusion complexes to glass and plastics). Investigating the performance of CFN-coated surfaces. Flexible and rigid plastic materials and glass coated with CFN demonstrated bactericidal activity towards Gram-negative (E. coli) and Gram-positive (Bac. cereus) bacteria. In addition, CFN-impregnated plastic material inhibited bacterial attachment and biofilm development. Testing the efficacy of CFN in food preservation trials. Efficient cold pasteurization of tender coconut water inoculated with E. coli and Listeriamonocytogeneswas performed by circulation through a column filled with CFN-coated glass beads. Combination of curcumin coating with blue light prevented bacterial cross contamination of fresh-cut melons through plastic surfaces contaminated with E. coli or Bac. licheniformis. Furthermore, coating of strawberries with CFN reduced fruit spoilage during simulated transportation extending the shelf life by 2-3 days. Implications, both scientific and agricultural BARD Report - Project4680 Page 2 of 17 Antimicrobial food-contact nanomaterials based on natural active principles will preserve food quality and ensure safety. Understanding mode of antimicrobial action of curcumin will allow enhancing its dark efficacy, e.g. by targeting the microbial cellular adaptation mechanisms.
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Sela, Shlomo, and Michael McClelland. Desiccation Tolerance in Salmonella and its Implications. United States Department of Agriculture, May 2013. http://dx.doi.org/10.32747/2013.7594389.bard.
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Salmonella enterica is a worldwide food-borne pathogen, which regularly causes large outbreaks of food poisoning. Recent outbreaks linked to consumption of contaminated foods with low water-activity, have raised interest in understanding the factors that control fitness of this pathogen to dry environment. Consequently, the general objective of this study was to extend our knowledge on desiccation tolerance and long-term persistence of Salmonella. We discovered that dehydrated STm entered into a viable-but-nonculturable state, and that addition of chloramphenicol reduced bacterial survival. This finding implied that adaptation to desiccation stress requires de-novo protein synthesis. We also discovered that dried STm cells develop cross-tolerance to multiple stresses that the pathogen might encounter in the agriculture/food environment, such as high or low temperatures, salt, and various disinfectants. These findings have important implications for food safety because they demonstrate the limitations of chemical and physical treatments currently utilized by the food industry to completely inactivate Salmonella. In order to identify genes involved in desiccation stress tolerance, we employed transcriptomic analysis of dehydrated and wet cells and direct screening of knock-out mutant and transposon libraries. Transcriptomic analysis revealed that dehydration induced expression of ninety genes and down-regulated seven. Ribosomal structural genes represented the most abundant functional group with a relatively higher transcription during dehydration. Other large classes of induced functional groups included genes involved in amino acid metabolism, energy production, ion transport, transcription, and stress response. Initial genetic analysis of a number of up-regulated genes was carried out). It was found that mutations in rpoS, yahO, aceA, nifU, rpoE, ddg,fnr and kdpE significantly compromised desiccation tolerance, supporting their role in desiccation stress response.
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Minz, Dror, Stefan J. Green, Noa Sela, Yitzhak Hadar, Janet Jansson, and Steven Lindow. Soil and rhizosphere microbiome response to treated waste water irrigation. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598153.bard.
Full textAbstract:
Research objectives : Identify genetic potential and community structure of soil and rhizosphere microbial community structure as affected by treated wastewater (TWW) irrigation. This objective was achieved through the examination soil and rhizosphere microbial communities of plants irrigated with fresh water (FW) and TWW. Genomic DNA extracted from soil and rhizosphere samples (Minz laboratory) was processed for DNA-based shotgun metagenome sequencing (Green laboratory). High-throughput bioinformatics was performed to compare both taxonomic and functional gene (and pathway) differences between sample types (treatment and location). Identify metabolic pathways induced or repressed by TWW irrigation. To accomplish this objective, shotgun metatranscriptome (RNA-based) sequencing was performed. Expressed genes and pathways were compared to identify significantly differentially expressed features between rhizosphere communities of plants irrigated with FW and TWW. Identify microbial gene functions and pathways affected by TWW irrigation*. To accomplish this objective, we will perform a metaproteome comparison between rhizosphere communities of plants irrigated with FW and TWW and selected soil microbial activities. Integration and evaluation of microbial community function in relation to its structure and genetic potential, and to infer the in situ physiology and function of microbial communities in soil and rhizospere under FW and TWW irrigation regimes. This objective is ongoing due to the need for extensive bioinformatics analysis. As a result of the capabilities of the new PI, we have also been characterizing the transcriptome of the plant roots as affected by the TWW irrigation and comparing the function of the plants to that of the microbiome. *This original objective was not achieved in the course of this study due to technical issues, especially the need to replace the American PIs during the project. However, the fact we were able to analyze more than one plant system as a result of the abilities of the new American PI strengthened the power of the conclusions derived from studies for the 1ˢᵗ and 2ⁿᵈ objectives. Background: As the world population grows, more urban waste is discharged to the environment, and fresh water sources are being polluted. Developing and industrial countries are increasing the use of wastewater and treated wastewater (TWW) for agriculture practice, thus turning the waste product into a valuable resource. Wastewater supplies a year- round reliable source of nutrient-rich water. Despite continuing enhancements in TWW quality, TWW irrigation can still result in unexplained and undesirable effects on crops. In part, these undesirable effects may be attributed to, among other factors, to the effects of TWW on the plant microbiome. Previous studies, including our own, have presented the TWW effect on soil microbial activity and community composition. To the best of our knowledge, however, no comprehensive study yet has been conducted on the microbial population associated BARD Report - Project 4662 Page 2 of 16 BARD Report - Project 4662 Page 3 of 16 with plant roots irrigated with TWW – a critical information gap. In this work, we characterize the effect of TWW irrigation on root-associated microbial community structure and function by using the most innovative tools available in analyzing bacterial community- a combination of microbial marker gene amplicon sequencing, microbial shotunmetagenomics (DNA-based total community and gene content characterization), microbial metatranscriptomics (RNA-based total community and gene content characterization), and plant host transcriptome response. At the core of this research, a mesocosm experiment was conducted to study and characterize the effect of TWW irrigation on tomato and lettuce plants. A focus of this study was on the plant roots, their associated microbial communities, and on the functional activities of plant root-associated microbial communities. We have found that TWW irrigation changes both the soil and root microbial community composition, and that the shift in the plant root microbiome associated with different irrigation was as significant as the changes caused by the plant host or soil type. The change in microbial community structure was accompanied by changes in the microbial community-wide functional potential (i.e., gene content of the entire microbial community, as determined through shotgun metagenome sequencing). The relative abundance of many genes was significantly different in TWW irrigated root microbiome relative to FW-irrigated root microbial communities. For example, the relative abundance of genes encoding for transporters increased in TWW-irrigated roots increased relative to FW-irrigated roots. Similarly, the relative abundance of genes linked to potassium efflux, respiratory systems and nitrogen metabolism were elevated in TWW irrigated roots when compared to FW-irrigated roots. The increased relative abundance of denitrifying genes in TWW systems relative FW systems, suggests that TWW-irrigated roots are more anaerobic compare to FW irrigated root. These gene functional data are consistent with geochemical measurements made from these systems. Specifically, the TWW irrigated soils had higher pH, total organic compound (TOC), sodium, potassium and electric conductivity values in comparison to FW soils. Thus, the root microbiome genetic functional potential can be correlated with pH, TOC and EC values and these factors must take part in the shaping the root microbiome. The expressed functions, as found by the metatranscriptome analysis, revealed many genes that increase in TWW-irrigated plant root microbial population relative to those in the FW-irrigated plants. The most substantial (and significant) were sodium-proton antiporters and Na(+)-translocatingNADH-quinoneoxidoreductase (NQR). The latter protein uses the cell respiratory machinery to harness redox force and convert the energy for efflux of sodium. As the roots and their microbiomes are exposed to the same environmental conditions, it was previously hypothesized that understanding the soil and rhizospheremicrobiome response will shed light on natural processes in these niches. This study demonstrate how newly available tools can better define complex processes and their downstream consequences, such as irrigation with water from different qualities, and to identify primary cues sensed by the plant host irrigated with TWW. From an agricultural perspective, many common practices are complicated processes with many ‘moving parts’, and are hard to characterize and predict. Multiple edaphic and microbial factors are involved, and these can react to many environmental cues. These complex systems are in turn affected by plant growth and exudation, and associated features such as irrigation, fertilization and use of pesticides. However, the combination of shotgun metagenomics, microbial shotgun metatranscriptomics, plant transcriptomics, and physical measurement of soil characteristics provides a mechanism for integrating data from highly complex agricultural systems to eventually provide for plant physiological response prediction and monitoring. BARD Report
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Ficht, Thomas, Gary Splitter, Menachem Banai, and Menachem Davidson. Characterization of B. Melinensis REV 1 Attenuated Mutants. United States Department of Agriculture, December 2000. http://dx.doi.org/10.32747/2000.7580667.bard.
Full textAbstract:
Brucella Mutagenesis (TAMU) The working hypothesis for this study was that survival of Brucella vaccines was directly related to their persistence in the host. This premise is based on previously published work detailing the survival of the currently employed vaccine strains S19 and Rev 1. The approach employed signature-tagged mutagenesis to construct mutants interrupted in individual genes, and the mouse model to identify mutants with attenuated virulence/survival. Intracellular survival in macrophages is the key to both reproductive disease in ruminants and reticuloendothelial disease observed in most other species. Therefore, the mouse model permitted selection of mutants of reduced intracellular survival that would limit their ability to cause reproductive disease in ruminants. Several classes of mutants were expected. Colonization/invasion requires gene products that enhance host-agent interaction or increase resistance to antibacterial activity in macrophages. The establishment of chronic infection requires gene products necessary for intracellular bacterial growth. Maintenance of chronic infection requires gene products that sustain a low-level metabolism during periods characterized little or no growth (1, 2). Of these mutants, the latter group was of greatest interest with regard to our originally stated premise. However, the results obtained do not necessarily support a simplistic model of vaccine efficacy, i.e., long-survival of vaccine strains provides better immunity. Our conclusion can only be that optimal vaccines will only be developed with a thorough understanding of host agent interaction, and will be preferable to the use of fortuitous isolates of unknown genetic background. Each mutant could be distinguished from among a group of mutants by PCR amplification of the signature tag (5). This approach permitted infection of mice with pools of different mutants (including the parental wild-type as a control) and identified 40 mutants with apparently defective survival characteristics that were tentatively assigned to three distinct classes or groups. Group I (n=13) contained organisms that exhibited reduced survival at two weeks post-infection. Organisms in this group were recovered at normal levels by eight weeks and were not studied further, since they may persist in the host. Group II (n=11) contained organisms that were reduced by 2 weeks post infection and remained at reduced levels at eight weeks post-infection. Group III (n=16) contained mutants that were normal at two weeks, but recovered at reduced levels at eight weeks. A subset of these mutants (n= 15) was confirmed to be attenuated in mixed infections (1:1) with the parental wild-type. One of these mutants was eliminated from consideration due to a reduced growth rate in vitro that may account for its apparent growth defect in the mouse model. Although the original plan involved construction of the mutant bank in B. melitensis Rev 1 the low transformability of this strain, prevented accumulation of the necessary number of mutants. In addition, the probability that Rev 1 already carries one genetic defect increases the likelihood that a second defect will severely compromise the survival of this organism. Once key genes have been identified, it is relatively easy to prepare the appropriate genetic constructs (knockouts) lacking these genes in B. melitensis Rev 1 or any other genetic background. The construction of "designer" vaccines is expected to improve immune protection resulting from minor sequence variation corresponding to geographically distinct isolates or to design vaccines for use in specific hosts. A.2 Mouse Model of Brucella Infection (UWISC) Interferon regulatory factor-1-deficient (IRF-1-/- mice have diverse immunodeficient phenotypes that are necessary for conferring proper immune protection to intracellular bacterial infection, such as a 90% reduction of CD8+ T cells, functionally impaired NK cells, as well as a deficiency in iNOS and IL-12p40 induction. Interestingly, IRF-1-/- mice infected with diverse Brucella abortus strains reacted differently in a death and survival manner depending on the dose of injection and the level of virulence. Notably, 50% of IRF-1-/- mice intraperitoneally infected with a sublethal dose in C57BL/6 mice, i.e., 5 x 105 CFU of virulent S2308 or the attenuated vaccine S19, died at 10 and 20 days post-infection, respectively. Interestingly, the same dose of RB51, an attenuated new vaccine strain, did not induce the death of IRF-1-/- mice for the 4 weeks of infection. IRF-1-/- mice infected with four more other genetically manipulated S2308 mutants at 5 x 105 CFU also reacted in a death or survival manner depending on the level of virulence. Splenic CFU from C57BL/6 mice infected with 5 x 105 CFU of S2308, S19, or RB51, as well as four different S2308 mutants supports the finding that reduced virulence correlates with survival Of IRF-1-/- mice. Therefore, these results suggest that IRF-1 regulation of multi-gene transcription plays a crucial role in controlling B. abortus infection, and IRF-1 mice could be used as an animal model to determine the degree of B. abortus virulence by examining death or survival. A3 Diagnostic Tests for Detection of B. melitensis Rev 1 (Kimron) In this project we developed an effective PCR tool that can distinguish between Rev1 field isolates and B. melitensis virulent field strains. This has allowed, for the first time, to monitor epidemiological outbreaks of Rev1 infection in vaccinated flocks and to clearly demonstrate horizontal transfer of the strain from vaccinated ewes to unvaccinated ones. Moreover, two human isolates were characterized as Rev1 isolates implying the risk of use of improperly controlled lots of the vaccine in the national campaign. Since atypical B. melitensis biotype 1 strains have been characterized in Israel, the PCR technique has unequivocally demonstrated that strain Rev1 has not diverted into a virulent mutant. In addition, we could demonstrate that very likely a new prototype biotype 1 strain has evolved in the Middle East compared to the classical strain 16M. All the Israeli field strains have been shown to differ from strain 16M in the PstI digestion profile of the omp2a gene sequence suggesting that the local strains were possibly developed as a separate branch of B. melitensis. Should this be confirmed these data suggest that the Rev1 vaccine may not be an optimal vaccine strain for the Israeli flocks as it shares the same omp2 PstI digestion profile as strain 16M.