Letteratura scientifica selezionata sul tema "Biofilm cultures"
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Articoli di riviste sul tema "Biofilm cultures"
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SHEFFIELD, C. L., T. L. CRIPPEN, K. ANDREWS, R. J. BONGAERTS e D. J. NISBET. "Planktonic and Biofilm Communities from 7-Day-Old Chicken Cecal Microflora Cultures: Characterization and Resistance to Salmonella Colonization†". Journal of Food Protection 72, n. 9 (1 settembre 2009): 1812–20. http://dx.doi.org/10.4315/0362-028x-72.9.1812.
Testo completoAbstract (sommario):
Information implicating bacterial biofilms as contributory factors in the development of environmental bacterial resistance has been increasing. There is a lack of information regarding the role of biofilms within the microbial ecology of the gastrointestinal tract of food animals. This work used a continuous-flow chemostat model derived from the ceca of 7-day-old chicks to characterize these communities and their ability to neutralize invasion by Salmonella enterica serovar Typhimurium. We characterized and compared the biofilm and planktonic communities within these microcosms using automated ribotyping and the Analytical Profile Index biotyping system. Eleven species from eight different genera were identified from six culture systems. Klebsiella pneumoniae was isolated from all planktonic communities and four of the biofilm communities. Three of the communities resisted colonization by Salmonella enterica serovar Typhimurium, two communities suppressed growth, and one community succumbed to colonization. In cultures that resisted colonization, no Salmonella could be isolated from the biofilm; in cultures that succumbed to colonization, Salmonella was consistently found within the biofilms. This study was one of a series that provided a molecular-based characterization of both the biofilm and planktonic communities from continuous-flow culture systems derived from the cecal microflora of chicks, ranging in age from day-of-hatch to 14 days old. The one common factor relating to successful colonization of the culture was the presence of Salmonella within the biofilm. The capacity to sequester the introduced Salmonella into the biofilm appears to be a contributing factor to the inability of these cultures to withstand colonization by the Salmonella.
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Schooling, S. R., U. K. Charaf, D. G. Allison e P. Gilbert. "A role for rhamnolipid in biofilm dispersion". Biofilms 1, n. 2 (aprile 2004): 91–99. http://dx.doi.org/10.1017/s147905050400119x.
Testo completoAbstract (sommario):
Biofilms are often considered as localized zones of high cell density. Quorum sensing provides a means for control of population processes and has been implicated in the regulation of biofilm activities. We present a role for quorum sensing in programmed detachment and dispersal processes. Biofilms of Pseudomonas aeruginosa PAO1 and its isogenic homoserine lactone (HSL) mutant P. aeruginosa PAO-JP2 were grown in batch culture on glass substrata; differences were found in the rate and extent of formation of biofilm. Climax communities were observed for PAO1 at 24 h. These were later accompanied by foaming, a drop in the surface tension of culture media and dispersal of the biofilm, after which no subsequent biofilm accretion occurred. PAO-JP2 cultures reformed biofilm post-detachment and did not foam. Prevention of biofilm reformation in the wild type was related to some component excreted into the culture medium. Rhamnolipid, a biosurfactant regulated by quorum sensing, was detected in PAO1 cultures. When rhamnolipid was added to freshly inoculated substrata, biofilm formation was inhibited. At 20 h, PAO1 biofilms were transferred to medium with added rhamnolipid: biofilm was relatively unaffected. Biofilm events were also studied in medium supplemented with N-butyryl-L-homoserine lactone, which is involved in the regulation of rhamnolipid synthesis. Both strains exhibited similar trends of rapid biofilm formation and dramatic changes in the rate and extent of biofilm accretion. In both cases, there was premature foaming, lowered surface tension and elevated rhamnolipid levels. A role for HSLs in maintenance of biofilm and events leading to dispersion of cells is proposed. This role would encompass dispersion but not necessarily detachment of cells from biofilm and supports a new function for rhamnolipid in pathogenesis, whereby rhamnolipid would promote the dissemination of cells from a nidus of infection.
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Frederick, Jesse R., James G. Elkins, Nikki Bollinger, Daniel J. Hassett e Timothy R. McDermott. "Factors Affecting Catalase Expression in Pseudomonas aeruginosa Biofilms and Planktonic Cells". Applied and Environmental Microbiology 67, n. 3 (1 marzo 2001): 1375–79. http://dx.doi.org/10.1128/aem.67.3.1375-1379.2001.
Testo completoAbstract (sommario):
ABSTRACT Previous work with Pseudomonas aeruginosa showed that catalase activity in biofilms was significantly reduced relative to that in planktonic cells. To better understand biofilm physiology, we examined possible explanations for the differential expression of catalase in cells cultured in these two different conditions. For maximal catalase activity, biofilm cells required significantly more iron (25 μM as FeCl3) in the medium, whereas planktonic cultures required no addition of iron. However, iron-stimulated catalase activity in biofilms was still only about one-third that in planktonic cells. Oxygen effects on catalase activity were also investigated. Nitrate-respiring planktonic cultures produced approximately twice as much catalase activity as aerobic cultures grown in the presence of nitrate; the nitrate stimulation effect could also be demonstrated in biofilms. Cultures fermenting arginine had reduced catalase levels; however, catalase repression was also observed in aerobic cultures grown in the presence of arginine. It was concluded that iron availability, but not oxygen availability, is a major factor affecting catalase expression in biofilms.
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MINEI, CLÁUDIA C., BRUNA C. GOMES, REGIANNE P. RATTI, CARLOS E. M. D'ANGELIS e ELAINE C. P. DE MARTINIS. "Influence of Peroxyacetic Acid and Nisin and Coculture with Enterococcus faecium on Listeria monocytogenes Biofilm Formation". Journal of Food Protection 71, n. 3 (1 marzo 2008): 634–38. http://dx.doi.org/10.4315/0362-028x-71.3.634.
Testo completoAbstract (sommario):
Biofilm formation is a matter of concern in food industries because biofilms facilitate the survival of pathogenic bacteria such as Listeria monocytogenes, which may contaminate food-processing equipment and products. In this study, nisin and two Enterococcus faecium strains were evaluated for their effect on biofilm formation by L. monocytogenes cultured in brain heart infusion broth and on stainless steel coupons. Elimination of preformed L. monocytogenes biofilms by peroxyacetic acid also was tested. Adhesion control experiments were performed with pure cultures of L. monocytogenes after swab collection of adhered cells, which were then enumerated on PALCAM agar plates and visualized by scanning electron microscopy. Formation of a biofilm was recorded when the number of adhered cells was at least 103 CFU/cm2. When L. monocytogenes was cocultured with E. faecium bac−, the number of adhered L. monocytogenes cells was 2.5 log lower (P = 0.002) when initially compared with the control culture, but after 6 h of incubation a biofilm was again detected. However, in coculture on stainless steel coupons, E. faecium bac+ inhibited L. monocytogenes adherence and did not allow biofilm formation for up to 48 h (P < 0.001). In the presence of nisin or after treatment with peroxyacetic acid, bacterial growth was reduced (P < 0.001) up to 4.6 and 5.6 log CFU/cm2, respectively, when compared with L. monocytogenes cultures on untreated coupons. However, after these treatments, cells were still present, and after 24 h of incubation, a renewed biofilm was detected in L. monocytogenes cultures treated with nisin. Although all tested conditions reduced L. monocytogenes growth to some extent, only coculture with E. faecium bac+ efficiently reduced biofilm formation, suggesting a potential control strategy for this pathogen.
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Vidal, Jorge E., Joshua R. Shak e Adrian Canizalez-Roman. "The CpAL Quorum Sensing System Regulates Production of Hemolysins CPA and PFO To Build Clostridium perfringens Biofilms". Infection and Immunity 83, n. 6 (30 marzo 2015): 2430–42. http://dx.doi.org/10.1128/iai.00240-15.
Testo completoAbstract (sommario):
Clostridium perfringensstrains produce severe diseases, including myonecrosis and enteritis necroticans, in humans and animals. Diseases are mediated by the production of potent toxins that often damage the site of infection, e.g., skin epithelium during myonecrosis. In planktonic cultures, the regulation of important toxins, such as CPA, CPB, and PFO, is controlled by theC. perfringensAgr-like (CpAL) quorum sensing (QS) system. Strains also encode a functional LuxS/AI-2 system. AlthoughC. perfringensstrains form biofilm-like structures, the regulation of biofilm formation is poorly understood. Therefore, our studies investigated the role of CpAL and LuxS/AI-2 QS systems and of QS-regulated factors in controlling the formation of biofilms. We first demonstrate that biofilm production by reference strains differs depending on the culture medium. Increased biomass correlated with the presence of extracellular DNA in the supernatant, which was released by lysis of a fraction of the biofilm population and planktonic cells. Whereas ΔagrBmutant strains were not able to produce biofilms, a ΔluxSmutant produced wild-type levels. The transcript levels of CpAL-regulatedcpaandpfoAgenes, but notcpb, were upregulated in biofilms compared to planktonic cultures. Accordingly, Δcpaand ΔpfoAmutants, in type A (S13) or type C (CN3685) backgrounds, were unable to produce biofilms, whereas CN3685Δcpbmade wild-type levels. Biofilm formation was restored in complemented Δcpa/cpaand ΔpfoA/pfoAstrains. Confocal microscopy studies further detected CPA partially colocalizing with eDNA on the biofilm structure. Thus, CpAL regulates biofilm formation inC. perfringensby increasing levels of certain toxins required to build biofilms.
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Wolyniak, E. A., B. R. Hargreaves e K. L. Jellison. "Retention and Release of Cryptosporidium parvum Oocysts by Experimental Biofilms Composed of a Natural Stream Microbial Community". Applied and Environmental Microbiology 75, n. 13 (15 maggio 2009): 4624–26. http://dx.doi.org/10.1128/aem.02916-08.
Testo completoAbstract (sommario):
ABSTRACT Cryptosporidium parvum oocysts accumulate on biofilm surfaces. The percentage of oocysts attached to biofilms remained nearly constant while oocysts were supplied to the system but decreased to a new steady-state level once oocysts were removed from the feed. More oocysts attached to summer biofilm cultures than winter biofilm cultures.
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Rahmani-Badi, Azadeh, Shayesteh Sepehr, Parisa Mohammadi, Mohammad Reza Soudi, Hamta Babaie-Naiej e Hossein Fallahi. "A combination of cis-2-decenoic acid and antibiotics eradicates pre-established catheter-associated biofilms". Journal of Medical Microbiology 63, n. 11 (1 novembre 2014): 1509–16. http://dx.doi.org/10.1099/jmm.0.075374-0.
Testo completoAbstract (sommario):
The catheterized urinary tract provides ideal conditions for the development of biofilm populations. Catheter-associated urinary tract infections (CAUTIs) are recalcitrant to existing antimicrobial treatments; therefore, established biofilms are not eradicated completely after treatment and surviving biofilm cells will carry on the infection. Cis-2-decenoic acid (CDA), an unsaturated fatty acid, is capable of inhibiting biofilm formation by Pseudomonas aeruginosa and of inducing the dispersion of established biofilms by multiple types of micro-organisms. Here, the ability of CDA to induce dispersal in pre-established single- and dual-species biofilms formed by Escherichia coli and Klebsiella pneumoniae was measured by using both semi-batch and continuous cultures bioassays. Removal of the biofilms by combined CDA and antibiotics (ciprofloxacin or ampicillin) was evaluated using microtitre plate assays (crystal violet staining). The c.f.u. counts were determined to assess the potential of combined CDA treatments to kill and eradicate pre-established biofilms formed on catheters. The effects of combined CDA treatments on biofilm surface area and bacteria viability were evaluated using fluorescence microscopy, digital image analysis and live/dead staining. To investigate the ability of CDA to prevent biofilm formation, single and mixed cultures were grown in the presence and absence of CDA. Treatment of pre-established biofilms with only 310 nM CDA resulted in at least threefold increase in the number of planktonic cells in all cultures tested. Whilst none of the antibiotics alone exerted a significant effect on c.f.u. counts and percentage of surface area covered by the biofilms, combined CDA treatments led to at least a 78 % reduction in biofilm biomass in all cases. Moreover, most of the biofilm cells remaining on the surface were killed by antibiotics. The addition of 310 nM CDA significantly prevented biofilm formation by the tested micro-organisms, even within mixed cultures, indicating the ability of CDA to inhibit biofilm formation by other types of bacteria in addition to Pseudomonas aeruginosa. These findings suggested that the biofilm-preventive characteristics of CDA make it a noble candidate for inhibition of biofilm-associated infections such as CAUTIs, which paves the way toward developing new strategies to control biofilms in clinical as well as industrial settings.
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Bryers, James D., e Huang Ching-Tsan. "Recombinant plasmid retention and expression in bacterial biofilm cultures". Water Science and Technology 31, n. 1 (1 gennaio 1995): 105–15. http://dx.doi.org/10.2166/wst.1995.0025.
Testo completoAbstract (sommario):
Any exposure of plasmid recombinant microorganisms to an open system environment, either inadvertently or intentionally, mandates research into those fundamental organism:plasmid processes that influence plasmid retention, transfer and expression. In open environmental systems a majority of the microbial activity occurs associated with an interface, within thin biological layers consisting of the cells and their insoluble extracellular polymer, layers known as biofilms. Thus any study regarding the fate of recombinant DNA sequences in an open system must consider processes that affect plasmid retention and expression in a biofilm culture. Biofilm cultures were cultivated in a parallel-plate flow cell reactor using E. coli DH5α which contained a recombinant plasmid with a plasmid stability factor, parB, (pTKW106) or without (pMJR1750). Using β-galactosidase as inducible reporter protein, plasmid retention and gene expression of pMJR1750 and pTKW106, in suspended versus biofilm cultures, were studied under different carbo to nitrogen ratios and plasmid induction levels. Recombinant biofilm formation under these environmental conditions was also investigated. Biofilm net accumulation rate of E. coli DH5α (pTKW106) decreases with increasing induction levels. The β-galactosidase production and ratios of β-galactosidase to total protein increase with increasing induction levels. Synthesis rates of total RNA, β-galactosidase mRNA and rRNA in biofilm cultures of E. coli DH5α (pTKW106) increase after induction by IPTG.
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Chinnici, Jennifer, Lisa Yerke, Charlene Tsou, Sujay Busarajan, Ryan Mancuso, Nishanth D. Sadhak, Jaewon Kim e Abhiram Maddi. "Candida albicans cell wall integrity transcription factors regulate polymicrobial biofilm formation with Streptococcus gordonii". PeerJ 7 (11 ottobre 2019): e7870. http://dx.doi.org/10.7717/peerj.7870.
Testo completoAbstract (sommario):
Polymicrobial biofilms play important roles in oral and systemic infections. The oral plaque bacterium Streptococcus gordonii is known to attach to the hyphal cell wall of the fungus Candida albicans to form corn-cob like structures in biofilms. However, the role of C. albicans in formation of polymicrobial biofilms is not completely understood. The objective of this study was to determine the role of C. albicans transcription factors in regulation of polymicrobial biofilms and antibiotic tolerance of S. gordonii. The proteins secreted by C. albicans and S. gordonii in mixed planktonic cultures were determined using mass spectrometry. Antibiotic tolerance of S. gordonii to ampicillin and erythromycin was determined in mixed cultures and mixed biofilms with C. albicans. Additionally, biofilm formation of S. gordonii with C. albicans knock-out mutants of 45 transcription factors that affect cell wall integrity, filamentous growth and biofilm formation was determined. Furthermore, these mutants were also screened for antibiotic tolerance in mixed biofilms with S. gordonii. Analysis of secreted proteomes resulted in the identification of proteins being secreted exclusively in mixed cultures. Antibiotic testing showed that S. gordonii had significantly increased survival in mixed planktonic cultures with antibiotics as compared to single cultures. C. albicans mutants of transcription factors Sfl2, Brg1, Leu3, Cas5, Cta4, Tec1, Tup1, Rim101 and Efg1 were significantly affected in mixed biofilm formation. Also mixed biofilms of S. gordonii with mutants of C. albicans transcription factors, Tec1 and Sfl2, had significantly reduced antibiotic tolerance as compared to control cultures. Our data indicates that C. albicans may have an important role in mixed biofilm formation as well as antibiotic tolerance of S. gordonii in polymicrobial biofilms. C. albicans may play a facilitating role than being just an innocent bystander in oral biofilms and infections.
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Kay, Matthew K., Thomas C. Erwin, Robert J. C. McLean e Gary M. Aron. "Bacteriophage Ecology inEscherichia coliandPseudomonas aeruginosaMixed-Biofilm Communities". Applied and Environmental Microbiology 77, n. 3 (3 dicembre 2010): 821–29. http://dx.doi.org/10.1128/aem.01797-10.
Testo completoAbstract (sommario):
ABSTRACTPhage therapy is being reexamined as a strategy for bacterial control in medical and other environments. As microorganisms often live in mixed populations, we examined the effect ofEscherichia colibacteriophage λW60 andPseudomonas aeruginosabacteriophage PB-1 infection on the viability of monoculture and mixed-species biofilm and planktonic cultures. In mixed-species biofilm communities,E. coliandP. aeruginosamaintained stable cell populations in the presence of one or both phages. In contrast,E. coliplanktonic populations were severely depleted in coculture in the presence of λW60. BothE. coliandP. aeruginosadeveloped phage resistance in planktonic culture; however, reduced resistance was observed in biofilm communities. Increased phage titers and reduced resistance in biofilms suggest that phage can replicate on susceptible cells in biofilms. Infectious phage could be released from mixed-culture biofilms upon treatment with Tween 20 but not upon treatment with chloroform. Tween 20 and chloroform treatments had no effect on phage associated with planktonic cells, suggesting that planktonic phage were not cell or matrix associated. Transmission electron microscopy showed bacteriophage particles to be enmeshed in the extracellular polymeric substance component of biofilms and that this substance could be removed by Tween 20 treatment. Overall, this study demonstrates how mixed-culture biofilms can maintain a reservoir of viable phage and bacterial populations in the environment.
Tesi sul tema "Biofilm cultures"
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Behnke, Sabrina. "Disinfection susceptibilities of detached biofilm clusters compared to planktonic cells and biofilms in single species and dual species cultures". Diss., Montana State University, 2011. http://etd.lib.montana.edu/etd/2011/behnke/BehnkeS0811.pdf.
Testo completoAbstract (sommario):
Detachment of cells and clusters from biofilms is an important process in the dissemination of microorganisms in industrial, environmental, and clinical settings but the disinfection susceptibilities of these cell clusters have not been sufficiently characterized. With the help of fluorescent microscopy and image analysis, naturally detaching cells and clusters from single species and dual species biofilms of Burkholderia cepacia and Pseudomonas aeruginosa grown in biofilm tubing reactors were analyzed for cluster size distributions and compared to the cluster sizes in chemostat cultures. The commonly used oxidizing agents free chlorine, chlorine dioxide and dissolved ozone were used for disinfection experiments and susceptibilities of detached clusters, planktonic cells, and intact biofilms in single species and dual species cultures were determined. Additionally, disinfection rates were calculated for chlorine and chlorine dioxide disinfection for all sample types and species. In experiments with chlorine as the disinfectant, a correlation between cluster sizes and disinfection efficacy was observed for single species only. Samples with the higher percentage of large clusters were more tolerant than samples with fewer large clusters. Chemostat samples and detached clusters from dual species reactors contained lower numbers of large clusters but were equally or less susceptible than their single species counterparts. Biofilms required chlorine doses up to ten times higher than chemostat or detached biofilm cells for total inactivation. Chlorine dioxide disinfection was independent of cluster size so that chemostat cells and detached clusters were similar with respect to log reductions and disinfection rates. Dual species chemostat cells, detached clusters, and biofilms were more tolerant to chlorine dioxide than the single species samples. As with chlorine, biofilms required much higher chlorine dioxide doses for total inactivation. Ozone was very efficient against B. cepacia chemostat cells and detached clusters but failed to inactivate biofilm samples with the concentrations used in this study. In general, detached clusters were more similar to chemostat cells and very different from biofilms with respect to disinfection susceptibilities and disinfection rates suggesting that biofilm-specific physical and physiological protection mechanisms may be lost shortly after the detachment event or may be absent in small clusters. 'Co-authored by Albert E. Parker, Dawn Woodall, and Anne K. Camper.'
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au, L. Hughes@murdoch edu, e Leonie Hughes. "Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures". Murdoch University, 2008. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20080523.134154.
Testo completoAbstract (sommario):
Nitrogen removal from wastewater is important for the revention of significant health and environmental impacts such as eutrophication. Nitrogen removal is achieved by the combined action of nitrification and denitrification. Nitrification is performed by autotrophic, slow growing microorganisms that require oxygen and are inhibited in the presence of denitrifiers when oxygen and COD are available due to competition for oxygen. Denitrification however, performed by relatively fast growing heterotrophic bacteria, is inhibited by oxygen and requires COD. This implies that nitrification and denitrification are mutually exclusive. The supply of oxygen to a fresh wastewater, high in ammonia and COD, causes waste of both oxygen and COD. Conservation of COD is therefore critical to efficient wastewater treatment. The approach investigated in this study to achieve complete nitrogen removal was to physically separate the nitrification and denitrification biomasses into separate bioreactors, supplying each with appropriate conditions for growth and activity.
A storage driven denitrification sequencing batch biofilm reactor (SDDR) was established which exhibited a high level of COD storage (up to 80% of influent COD) as poly-B-hydroxybutyrate capable of removing >99% of nitrogen from wastewaters with a C/N ratio of 4.7 kg COD/kg NNO3 . The SDDR was combined in sequential operation with a nitrification reactor to achieve complete nitrogen removal. The multiple stage, multiple biomass reactor was operated in sequence, with Phase 1 - COD storage in the storage driven denitrification biofilm; Phase 2 - ammonia oxidation in the nitrification reactor; and Phase 3 - nitrate reduction using the stored COD in the storage driven denitrification reactor. The overall rate of nitrogen removal observed was up to 1.1 mmole NH3 L1 h1 and >99% of nitrogen could be removed from wastewaters with a low C/N ratio of 3.9 kg COD/kg NNH3.
The multiple stage, multiple biomass system was limited in overall nitrogen removal the reduction in pH caused by nitrification. A parallel nitrification-denitrificatio (PND) reactor was developed in response to the pH control issue. The PND reactor was operated with Phase 1 COD storage in the storage driven denitrification biofilm and Phase 2 simultaneous circulation of reactor liquor between the denitrification and nitrification biofilms to achieve complete nitrogen removal and transfer of protons. The PND reactor performed competitively with the multistage reactor (removal of >99% nitrogen from wastewaters with feed ratios of 3.4 kg COD/kg NNH3) without the need for addition of buffering material to oderate the pH.
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Hughes, Leonie. "Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures". Hughes, Leonie (2008) Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures. PhD thesis, Murdoch University, 2008. http://researchrepository.murdoch.edu.au/674/.
Testo completoAbstract (sommario):
Nitrogen removal from wastewater is important for the revention of significant health and environmental impacts such as eutrophication. Nitrogen removal is achieved by the combined action of nitrification and denitrification. Nitrification is performed by autotrophic, slow growing microorganisms that require oxygen and are inhibited in the presence of denitrifiers when oxygen and COD are available due to competition for oxygen. Denitrification however, performed by relatively fast growing heterotrophic bacteria, is inhibited by oxygen and requires COD. This implies that nitrification and denitrification are mutually exclusive. The supply of oxygen to a fresh wastewater, high in ammonia and COD, causes waste of both oxygen and COD. Conservation of COD is therefore critical to efficient wastewater treatment. The approach investigated in this study to achieve complete nitrogen removal was to physically separate the nitrification and denitrification biomasses into separate bioreactors, supplying each with appropriate conditions for growth and activity.
A storage driven denitrification sequencing batch biofilm reactor (SDDR) was established which exhibited a high level of COD storage (up to 80% of influent COD) as poly-B-hydroxybutyrate capable of removing >99% of nitrogen from wastewaters with a C/N ratio of 4.7 kg COD/kg N–NO3 –. The SDDR was combined in sequential operation with a nitrification reactor to achieve complete nitrogen removal. The multiple stage, multiple biomass reactor was operated in sequence, with Phase 1 - COD storage in the storage driven denitrification biofilm; Phase 2 - ammonia oxidation in the nitrification reactor; and Phase 3 - nitrate reduction using the stored COD in the storage driven denitrification reactor. The overall rate of nitrogen removal observed was up to 1.1 mmole NH3 L–1 h–1 and >99% of nitrogen could be removed from wastewaters with a low C/N ratio of 3.9 kg COD/kg N–NH3.
The multiple stage, multiple biomass system was limited in overall nitrogen removal the reduction in pH caused by nitrification. A parallel nitrification-denitrificatio (PND) reactor was developed in response to the pH control issue. The PND reactor was operated with Phase 1 – COD storage in the storage driven denitrification biofilm and Phase 2 – simultaneous circulation of reactor liquor between the denitrification and nitrification biofilms to achieve complete nitrogen removal and transfer of protons. The PND reactor performed competitively with the multistage reactor (removal of >99% nitrogen from wastewaters with feed ratios of 3.4 kg COD/kg N–NH3) without the need for addition of buffering material to oderate the pH.
4
Gillmann, Antoine. "Étude de la survie de contaminants bactériens modèles d’origine industrielle, isolés d’environnements oligotrophes, et élaboration de milieux synthétiques permettant leur croissance". Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAJ004/document.
Testo completoAbstract (sommario):
La mise au point de milieux de culture permettant de mettre en évidence rapidement et de manière reproductible des micro-organismes exigeants représenterait une évolution significative dans le contrôle des produits et procédés industriels. Deux milieux de culture synthétiques ont été élaborés pour répondre à ce besoin. Le développement des milieux de culture a été réalisé en combinant l’analyse de composés nutritionnels à l’étude de certains métabolismes bactériens. Les formulations des milieux de culture obtenues permettent ainsi la croissance de micro-organismes aux exigences nutritionnelles très variées comme ceux fréquemment isolés dans l’eau industrielle. En parallèle, des expériences sur des biofilms multi-espèces, utilisant des bactéries isolées de systèmes d’eau industrielle, ont permis d’observer que la survie des bactéries en milieu pauvre en nutriments, est dépendante d’interactions coopératives, basées sur le « swarming » et le « hitchhiking »The development of culture media to quickly and reproducibly detect fastidious microorganisms represents a significant change in the control of industrial products and processes.Two synthetic culture media have been developed to reach specifications. The development was performed by combining the analysis of nutritional compounds to the study of specific bacterial metabolisms. The formulations of the resulting culture media allow the growth of microorganisms with different nutritional requirements as those frequently isolated in industrial water.In parallel experiments on multi-species biofilms, using bacteria isolated from industrial water systems, it was observed that the survival of bacteria in nutrient-poor environments is dependent on cooperative interactions, based on "swarming" and "hitchhiking"
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Pierra, Mélanie. "Couplage de la fermentation sombre et de l’électrolyse microbienne pour la production d’hydrogène : formation et maintenance du biofilm électro-actif". Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20150/document.
Testo completoAbstract (sommario):
L'hydrogène, qui constitue une solution alternative et durable à l’usage d’énergies fossiles, est produit essentiellement par reformage de combustibles fossiles (95%). Des filières de production plus soucieuses de l'environnement sont envisagées. Deux familles de technologies sont explorées: 1) par décomposition thermochimique ou électrochimique de l'eau et 2) à partir de différentes sources de biomasse. Parmi celles-ci, les cellules d'électrolyse microbienne ou «Microbial electrolysis cell (MEC)» permettent de produire de l'hydrogène par électrolyse de la matière organique. Une MEC consiste en une cathode classique qui assure la production d'hydrogène par la réduction électrochimique de l'eau, associée à une bioanode qui oxyde des substrats organiques en dioxyde de carbone. Ce processus d'oxydation n'est possible que grâce au développement sur l'anode d'un biofilm microbien électroactif qui joue le rôle d'électro-catalyseur. Par rapport aux procédés courants d'électrolyse de l'eau, une MEC requière un apport énergétique 5 à 10 fois plus faibles. En outre, les procédés « classiques » de production de bio-hydrogène par voie fermentaire en cultures mixtes convertissent des sucres avec des rendements limités à 2-3 moles d'hydrogène par mole d'hexose tout en coproduisant des acides organiques. Alimenté par de l'acétate, une MEC produit au maximum 3 moles d'hydrogène/mole d'acétate. Le couplage de la fermentation à un procédé d'électrolyse microbienne pourrait donc produire de 8 à 9 moles d'hydrogène/mole d'hexose, soit un grand pas vers la limite théorique de 12 moles d'hydrogène/mole d'hexose. L'objectif de cette thèse est d'analyser les liens entre la structure des communautés microbiennes dans les biofilms électroactifs et en fermentation, les individus qui les composent et les fonctions macroscopiques (électroactivité du biofilm, production d'hydrogène) qui leur sont associées dans des conditions permettant de réaliser le couplage des deux procédés. L'originalité de cette étude a été de travailler en milieu salin (30-35 gNaCl/L), favorable au transport de charges dans l'électrolyte de la MEC. Dans un premier temps, la faisabilité de la fermentation en conditions salines (3-75 gNaCl/L) a été démontrée en lien avec l'inhibition de la consommation de l'hydrogène produit et une forte prédominance d'une nouvelle souche de Vibrionaceae à des concentrations en sel supérieures à 58 gNaCl/L. D'autre part, la mise en œuvre de biofilms électroactifs dans des conditions compatibles avec la fermentation sombre a permis la sélection d'espèces dominantes dans les biofilms anodiques et présentant des propriétés électroactives très prometteuses (Geoalkalibacter subterraneus et Desulfuromonas acetoxidans) jusqu'à 8,5 A/m². En parallèle, la sélection microbienne opérée lors d'une méthode d'enrichissement utilisée pour sélectionner ces espèces à partir d'une source d'inoculum naturelle sur leur capacité à transférer leurs électrons à des oxydes de Fer(III) a été étudiée. Une baisse des performances électroactives du biofilm liée à une divergence de sélection microbienne dans ces deux techniques de sélection mène à limiter le nombre de cycle d'enrichissement sur Fer(III). Cependant, l'enrichissement sur Fer(III) reste une alternative efficace de pré-selection d'espèces électroactives qui permet une augmentation de rendement faradique de 30±4% à 99±8% par rapport au biofilm obtenu avec un inoculum non pré-acclimaté. Enfin, l'ajout d'espèces exogènes issues de la fermentation sombre sur le biofilm électroactif a révélé une baisse de l'électroactivité du biofilm se traduisant par une diminution de la densité de courant maximale produite. Cette baisse pourrait s'expliquer par à une diminution de la vitesse de transfert du substrat due à un épaississement apparent du biofilm. Cependant, un maintien de sa composition microbienne et de la quantité de biomasse laisse supposer une production d'exopolymères (EPS) dans le biofilm en situation de couplageNowadays, alternative and sustainable solutions are proposed to avoid the use of fossil fuel. Hydrogen, which constitutes a promising energy vector, is essentially produced by fossil fuel reforming (95%). Environmentally friendly production systems have to be studied. Two main families of technologies are explored to produce hydrogen: 1) by thermochemical and electrochemical decomposition of water and 2) from different biomass sources. Among those last ones, microbial electrolysis cells (MEC) allow to produce hydrogen by electrolysis of organic matter. A MEC consists in a classical cathode, which provides hydrogen production by electrochemical reduction of water, associated to a bio-anode that oxidizes organic substrates into carbon dioxide. This process is only possible because of the anodic development of an electroactive microbial biofilm which constitutes an electrocatalyst. In comparison to classical water electrolysis process, a MEC requires 5 to 10 times less electrical energy and therefore reduces the energetic cost of produced hydrogen. Furthermore, classical process of dark fermentation in mixed cultures converts sugars (saccharose, glucose) to hydrogen with a limited yield of 2-3 moles of hydrogen per mole of hexose because of the coproduction of organic acids (mainly acetic and butyric acids). Fed with acetate, a MEC can produce up-to 3 moles of hydrogen per mole of acetate. Therefore, the association of these two processes could permit to produce 8 to 9 moles of hydrogen per mole of hexose, which represents a major step toward the theoretical limit of 12 moles of hydrogen per mole of hexose.Therefore, this work aims at analyzing the relationship between microbial community structures and compositions and the associated macroscopic functions (biofilm electroactive properties, hydrogen production potential) in electroactive biofilms and in dark fermentation in conditions allowing the coupling of the two processes. The originality of this study is to work in saline conditions (30-35 gNaCl/L), which favors the charges transfer in the MEC electrolyte.First of all, feasibility of dark fermentation in saline conditions (3-75 gNaCl/L) has been shown. This was linked to an inhibition of produced hydrogen consumption and the predominance of a new Vibrionaceae species at salt concentrations higher than 58 gNaCl/L. Secondly, electroactive biofilm growth in conditions compatibles to dark fermentation (pH 5.5-7 and fed with different organic acids) allowed to select dominant microbial species in anodic biofilms that present promising electroactive properties (Geoalkalibacter subterraneus and Desulfuromonas acetoxidans) with maximum current densities up to 8.5 A/m². In parallel, the microbial selection occurring during iron-reducing enrichment method used to select species from a natural inoculum source and based on their capacity to transfer electrons to iron oxydes (Fe(III)) has been studied. A decrease of electroactive performances of the biofilm linked to the divergence of microbial selection led to a limitation of the number of iron-enrichment steps. However, enrichment on Fe(III) presents an efficient alternative to pre-select electroactive species with an increase of coulombic efficiency from 30±4% to 99±8% in comparison with a biofilm obtained with a non-acclimated inoculum. Finally, the addition of exogenous bacteria from a dark fermenter on the electroactive biofilm revealed a decrease of electroactivity with a decrease of maximum current density produced. This diminution could be explained by a lower substrate transfer due to an apparent thickening of the biofilm. Nevertheless, the stability of microbial composition and of bacterial quantity on the anode suggests that a production of exopolymers (EPS) occurred
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Phoeurng, Sackona. "Mise en évidence de Listeria spp. Dans le contexte alimentaire au Cambodge et étude du comportement de L. Monocytogenes en biofilm sous l'influence de Pseudomonas fluorescens et de désinfectants". Dijon, 2002. http://www.theses.fr/2002DIJOS054.
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Dastidar, Aniruddha. "ARSENITE OXIDATION BY PURE CULTURES OF THIOMONAS ARSENIVORANS STRAIN B6 IN BIOREACTOR SYSTEMS". UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/70.
Testo completoAbstract (sommario):
The removal of arsenic toxicity from water is accomplished by a preliminary preoxidative step transforming the most toxic form, arsenite (As (III)), to the least toxic form, arsenate (As (V)). The potential of As (III) oxidation to As (V) was initially investigated in batch reactors using the chemoautotrophic Thiomonas arsenivorans strain b6 under varying initial As (III) and cell concentrations and at optimal pH and temperature conditions (pH 6.0 and temperature 30°C). The strain b6 completely oxidized As (III) to As (V) during exponential growth phase for lower levels of As (III) concentrations (≤ 100 mg/L) but continued into stationary phase of growth for higher levels (≥ 500 mg/L). Other important factors such as oxygen and carbon limitations during biological As (III) oxidation were also evaluated. The biokinetic parameters of the strain b6 were estimated using a Haldanesubstrate inhibition model with the aid of a non-linear estimation technique.
Microbial As (III) oxidation was further investigated in continuous-flow bioreactors (CSTR and biofilm reactor) under varying As (III) loading rates. Both the reactors achieved As (III) oxidation efficiency exceeding 99% during the steady-state conditions. The reactors were also able to recover from an As (III) overloading phase establishing the resilient nature of the microorganism. The basic mass balance expressions on As (III) and biomass along with the Monod model were used to linearly estimate the biokinetic parameters in the CSTR study. However, in the biofilm study, a steady-state flux model was used to estimate the same parameters. The performance of the model was very good in simulating the transient and steady-state conditions.
Finally, the potential application of one-stage and two-stage reactor systems was investigated for the near complete removal of arsenic. Activated alumina was used as the adsorbent for the As (V) produced by the biological oxidation of As (III). The two-stage reactor process performed better than the one-stage reactor system in lowering the arsenic level below the detection limit (1 mg/L) for at least eight days of operation. However, pH fluctuations and probable competition from ions such as PO43- , SO42-, and Cl- severely impacted the performance of the reactors. Further study is needed to improve the overall efficiency of the reactor systems for achieving complete removal of arsenic for a longer operating time.
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Borrel, Valérie. "Influence du microenvironnement sur la virulence et la formation de biofilm de Cutibacterium acnes". Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR035/document.
Testo completoAbstract (sommario):
L’acné vulgaris est considérée comme l’une des maladies de la peau les plus communes. Sa pathologie n’est pas encore totalement élucidée mais Cutibacterium acnes (précédemment Propionibacterium acnes), est considérée comme l’un des facteurs principaux de son développement. Cette bactérie est caractérisée par une importante variabilité génomique et les souches de ribotype 4 et 5 (RT4 et RT5) ont été associées à l’acné tandis que celles de RT6 sont considérées comme commensales. Les différences physiologiques de ces types de C. acnes en fonction de leur environnement (différents milieux de culture) a été étudiée. De plus, un lien a été décrit entre l’acné et le stress, l’utilisation de produits cosmétiques sans conservateurs est en plein essor et les bactéries sont capables de réagir à des facteurs locaux par des changements métaboliques importants. Dans ce contexte, l’impact de deux catécholamines et de deux produits cosmétiques a également été testé. Cette étude montre que les différents types de C. acnes sont adaptés à des niches écologiques différentes : les souches acnéiques semblent adaptées à un développement dans les glandes sébacées tandis que les souches commensales se trouveraient plutôt en surface et en haut du follicule pileux. De plus, le type acnéique semble associé à un potentiel inflammatoire plus important, ce qui conforte sa possible implication dans l’acné. Les catécholamines (épinéphrine et norépinéphrine) peuvent stimuler leur capacité de formation de biofilm et C. acnes traité avec ces molécules peut stimuler la lipogenèse des sébocytes. Un lien pourrait donc être fait entre le stress et le rôle potentiel de C. acnes dans l’acné. D’autre part, cette étude montre également que le biofilm de C. acnes peut être diminué en présence d’eau thermale d’Uriage et/ou d’un polysaccharide riche en rhamnose (PS291®)Acne vulgaris is one of the most common skin diseases. Its pathogenesis is still unclear but Cutibacterium acnes (former Propionibacterium acnes) is considered as essential for its development. This bacterium is characterized by high genomic variability and some strains as ribotype 4 and 5 (RT4 and RT5) strains are highly associated with acne whereas RT6 strains are enriched in healthy skin. The physiological differences between these C. acnes types were evaluated dependently of their environment (culture media). Moreover, a link between acne and stress has been described, the use of preservative-free-cosmetics is burgeoning and bacteria can react to local factors by important metabolic changes. In this respect, two catecholamines and two cosmetic compounds were also tested. This study shows that the different C. acnes types are adapted to different ecological niches: acneic strains are adapted to sebaceous glands whereas non-acneic strains are more adapted to the skin surface and the upper hair follicle. Moreover, the acneic type seems associated to a more important inflammatory potential, which consolidates its possible implication in acne. The catecholamines can stimulate its biofilm formation and C. acnes treated by these molecules can stimulated the lipogenesis in sébocytes. Then, this study highlights the existence of a link between stress and the potential role of C. acnes in acne. Elsewhere, this study shows that the biofilm of C. acnes can be inhibited by Uriage thermal water and/or a rhamnose-rich polysaccharide (PS291®)
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Goudot, Sébastien. "Étude des facteurs d'influence de l'écologie de Naegleria fowleri dans les biofilms". Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0304/document.
Testo completoAbstract (sommario):
Dans l'objectif d'anticiper et de réduire la prolifération de l'amibe pathogène Naegleria fowleri dans les circuits de refroidissement de certaines centrales électriques, notre travail vise à mieux comprendre l'écologie de cette amibe dans des environnements complexes tels que les biofilms d'eau douce récemment reconnus comme niche écologique préférentielle des amibes libres. Des essais de laboratoire ont été réalisés pour déterminer l'impact des facteurs environnementaux naturels et anthropiques: température, nature du matériau support de la formation du biofilm, charge nutritionnelle et monochloramination sur le comportement et le devenir de Naegleria fowleri dans le biofilm. Ces travaux ont permis de démontrer que la survie, l'implantation, la croissance, le maintien et le déclin de Naegleria fowleri dans les biofilms sont principalement gouvernés par la concomitance des facteurs température et ressource nutritive. Les autres facteurs: nature du matériau, désinfection à la monochloramine et compétition amibienne, se présentent plutôt comme des paramètres de perturbation ou d'inhibition de cette dynamique. Par ailleurs, les résultats obtenus sur la colonisation du biofilm par les amibes confortent le rôle prépondérant de cet habitat comme réservoir naturel des amibes libres et Naegleria fowleriThis study is aiming at preventing and reducing the proliferation of the pathogenic free-living amoeba Naegleria fowleri in several power plant cooling circuits. This work contributes to provide a better understanding of the ecology of this amoeba in complex environments such as freshwater biofilms, which recently has been recognized as privileged ecological niche for free-living amoebae. Laboratory tests were conducted to determine the impact of environmental factors such as temperature, type of support material for the biofilm formation, nutritional resources and monochloramination treatment on the behavior and the fate of Naegleria fowleri in the biofilm. This work has demonstrated that the survival, implantation, maintain, growth and decline of Naegleria fowleri in biofilms are mainly governed by a combination of the temperature and nutritional resource factors. The other factors: type of support material, monochloramination treatment, and amoebic competition, appeared rather as disruptive or inhibitory parameters of this dynamic. Moreover, the obtained results for the amoebic colonization of the biofilm matrix confirm the crucial role of this habitat as natural reservoir for free-living amoebae and Naegleria fowleri
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Pandin, Caroline. "Exploration des mécanismes impliqués dans la bioprotection d'Agaricus bisporus par les biofilms de Bacillus subtilis QST713". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLA025/document.
Testo completoAbstract (sommario):
Les pertes alimentaires mondiales se chiffrent à environ un tiers des aliments destinés à la consommation humaine, soit environ 1,3 milliards de tonnes par an (FAO). Une large fraction de ces pertes est due aux altérations microbiologiques des denrées alimentaires. L’utilisation de produits phytosanitaires reste aujourd’hui la solution la plus largement utilisée en agriculture pour limiter ces pertes. Cependant, avec le plan EcoPhyto 2, le gouvernement français a pour objectif de réduire de 50% l’usage des pesticides chimiques d’ici 2025, en particulier en promouvant l’émergence du biocontrôle. Pour développer cette approche, il est cependant nécessaire de comprendre, pour mieux les maitriser, les mécanismes sous-jacents. Les différents modes d’action de biocontrôle par les microorganismes décrits sont la stimulation des défenses naturelles des plantes, la production de substances antimicrobienne et la compétition nutritionnelle. L'originalité de ce projet est d'intégrer le mode de vie en biofilm dans les mécanismes de bioprotection (compétition spatiale et nutritionnelle, libération de principes antimicrobiens). Dans la filière Française des champignons de couche (Agaricus bisporus), l’agent de biocontrôle utilisé depuis 2008 par plus de 80 % de la filière, est Bacillus subtilis QST713. Ce biofongicide montre une nette efficacité contre Trichoderma aggressivum, la principale moisissure à l’origine de pertes économiques lors de la culture d’A. bisporus. Afin d’accompagner la filière dans cette voie biologique, nous avons entrepris de séquencer et étudier le génome de cette souche, afin de déterminer son potentiel de biocontrôle et sa capacité à former des biofilms. Nous avons également évalué l’impact de ce biofongicide sur la dynamique des communautés microbiennes du compost de culture d’A. bisporus exposé ou non à T. aggressivum. Enfin, l'étude de la reprogrammation cellulaire de cet agent de biocontrôle lors de sa culture en micromodèles axéniques, nous a permis une meilleure compréhension des phénomènes de colonisation des substrats et d'inhibition des flores indésirables. Ce projet a permis d’enrichir les connaissances vis-à-vis des mécanismes de biocontrôle dans la filière des champignons et pourra permettre une possible application à d’autres filières agricolesWorldwide, food losses amount for about one-third of food for human consumption, 1.3 billion tons per year (FAO). A large fraction of these losses are due to microbiological alterations. The use of phytosanitary products remains today the most widely used solution in agriculture to limit these losses. However, with the EcoPhyto 2 plan, the French government aims to reduce the use of chemical pesticides by 50% by 2025, in particular by promoting the emergence of biocontrol. To develop this approach, it is necessary to understand the underlying mechanisms. The different modes of action of biocontrol by the microorganisms described are the stimulation of the natural defenses of the plants, the production of antimicrobial substances and the nutritional competition. The originality of this project is to integrate the biofilm mode of life into bioprotection mechanisms (spatial and nutritional competition, release of antimicrobial principles). In the French sector of the button mushrooms (Agaricus bisporus) culture, the biocontrol agent used since 2008 by more than 80% of the sector, is Bacillus subtilis QST713. This biofungicide shows a clear efficacy against Trichoderma aggressivum, the main mold causing economic losses during the cultivation of A. bisporus. To accompany the sector in this biological pathway, we have sequenced and studied the genome of this strain, in order to determine its biocontrol potential and its ability to form biofilms. We also evaluated the impact of this biofungicide on the dynamics of microbial communities in A. bisporus culture compost exposed or not to T. aggressivum. Finally, the study of the cellular reprogramming of this biocontrol agent during the culture in axenic micromodels allowed us a better understanding of the substrates colonization phenomenon and the inhibition of undesirable flora. This project will enrich the knowledge of the biocontrol mechanisms used in the mushroom industry and may allow a possible application to other agricultural sectors
Libri sul tema "Biofilm cultures"
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Ehrlich, Garth D., Patrick J. DeMeo, J. William Costerton e Heinz Winkler, a cura di. Culture Negative Orthopedic Biofilm Infections. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29554-6.
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Crichton, Michael. Rising Sun / The Andromeda Strain / Binary. London: Cresset, 1994.
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Culture Negative Orthopedic Biofilm Infections Springer Series on Biofilms. Springer, 2012.
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Costerton, J. William, Heinz Winkler, Garth D. Ehrlich e Patrick J. DeMeo. Culture Negative Orthopedic Biofilm Infections. Springer, 2015.
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Clair, Larry St. Biodeterioration of Stone Surfaces: Lichens And Biofilms As Weathering Agents Of Rocks And Cultural Heritage. Springer, 2011.
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L, St Clair Larry, e Seaward M. R. D, a cura di. Biodeterioration of stone surfaces: Lichens and biofilms as weathering agents of rocks and cultural heritage. Dordrecht: Kluwer Academic Publishers, 2004.
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Mabey, David, Hasan E. Baydoun e Jamil D. Bayram. Prosthetic Joint Infections. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199976805.003.0048.
Testo completoAbstract (sommario):
Prosthetic joint infection (PJI), a complication of joint replacement surgery, presents with fever, joint pain, erythema, effusion, and joint loosening. Many advances have decreased the risk of infection, such as the use of perioperative antimicrobial prophylaxis and intraoperative laminar airflow. Joint fluid analysis should be pursued by the orthopedic surgeons; primary and acute care providers should consult the definitive care team and refer these patients for admission. Organisms causing prosthetic joint infections often grow in biofilms, which make them difficult to treat. Surgical treatment options include one or two-stage prosthesis exchange, debridement with retention of the prosthesis, resection arthroplasty, arthrodesis, or amputation. Antibiotic therapy should be guided by intraoperative cultures and selected in consultation with the infectious disease service.
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Ely, Roger Lee. Startup and performance of a gas-permeable-membrane-supported (GPMS) biofilm system using a mixed culture of methylotrophs to degrade methylene chloride, chloroform, and carbon tetrachloride. 1986.
Cerca il testo completoCapitoli di libri sul tema "Biofilm cultures"
1
Cappitelli, Francesca, e Federica Villa. "Novel Antibiofilm Non-Biocidal Strategies". In Microorganisms in the Deterioration and Preservation of Cultural Heritage, 117–36. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69411-1_5.
Testo completoAbstract (sommario):
AbstractSubaerial biofilm (SAB) formation on cultural heritage objects is often considered an undesirable process in which microorganisms and their by-products, e.g., enzymes and pigments, cause damage or alteration to a surface. Since biofilms are widespread phenomena, there has been a high demand for preventive and control strategies that resist their formation or reduce their negative effects once formed. Up to date, the main strategy to control biofilms has been the use of biocides. Because of their intrinsic properties, biocidal products can pose risks to humans, animals, and the environment. In this chapter, the authors call “green” only those alternative strategies to biocides able to prevent/control biofilms but that do not kill microorganisms, i.e., irrespective of the use of natural compounds. Here, we describe some of the methods that are most commonly used to test the effectiveness of antibiofilm compounds with multiple-species biofilm model systems. A unified terminology and well described protocols and guidelines are still required to compare and test the effectiveness of traditional or novel compounds against biofilms retrieved on heritage surfaces.
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Gu, Ji-Dong, e Yoko Katayama. "Microbiota and Biochemical Processes Involved in Biodeterioration of Cultural Heritage and Protection". In Microorganisms in the Deterioration and Preservation of Cultural Heritage, 37–58. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69411-1_2.
Testo completoAbstract (sommario):
AbstractThe world cultural heritage sites face new challenges for an effective protection and management because of destruction and damage initiated by both natural and anthropogenic causes. Fresh rock and sandstone surfaces of buildings are quickly colonized and covered by a layer of microorganisms, including phototrophs, lithotrophs, and heterotrophs to form a biofilm that alters the local conditions of the stone surfaces, especially under the favorable tropical climate conditions for autotrophic microorganisms and plants. Biofilms had been studied with indigenous or pure cultures of isolated microorganisms, but the selective ones that contribute to deterioration of the cultural heritage cannot be confirmed easily. Currently, high-throughput sequencing and metegenomics analyses are capable of obtaining microbial community and composition in great depth, but they also suffer from similar weakness unable to identify the culprits in the community. With these as background, this article presents a different approach by focusing on the biochemical processes and the responsible microorganisms involved to reveal the destruction processes for management and protection. Among these different functional groups of microorganisms, lichens are known as pioneering rock-decomposing microorganisms, and both sulfur-oxidizing bacteria and fungi participate in the decomposition of sandstone via sulfur cycling and initiation of salt attack of the stone afterward, resulting in defoliation and cracking of stone. Other microorganisms including ammonia-oxidizing bacteria and archaea, especially the latter, have been recently detected on sandstone monuments providing evidence on the new organisms involved in the deterioration of cultural heritage and buildings. In addition, fungi can colonize the surfaces of the matured biofilms and play a new role in the removal of them, which has a potential biotechnological application in conservation of cultural heritage. The new proposed approach by focusing the microorganisms with identified biochemical function is more productive than a description of the community composition and assembly when assessing cultural heritage biodeterioration, and this provides basic and useful information for effective protection strategies and management.
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Congestri, Roberta, e Patrizia Albertano. "Benthic Diatoms in Biofilm Culture". In The Diatom World, 227–43. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1327-7_10.
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Ehrlich, G. D., P. J. DeMeo e J. W. Costerton. "The Problem of Culture-Negative Infections". In Springer Series on Biofilms, 1–15. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29554-6_1.
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Ehrlich, G. D., Patrick DeMeo, Michael Palmer, T. J. Sauber, Dan Altman, Greg Altman, Nick Sotereanos et al. "Culture-Negative Infections in Orthopedic Surgery". In Springer Series on Biofilms, 17–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29554-6_2.
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Spenceley, H., C. S. Dow e J. T. Holah. "Development of Mixed Culture Biofilms on Stainless Steel". In Biofilms — Science and Technology, 395–402. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-1824-8_33.
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Parvizi, Javad. "Diagnosing Periprosthetic Joint Infection: Cultures, Molecular Markers, and the Ibis Technology". In Springer Series on Biofilms, 77–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29554-6_6.
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Pinna, Daniela. "Microbial Growth and its Effects on Inorganic Heritage Materials". In Microorganisms in the Deterioration and Preservation of Cultural Heritage, 3–35. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69411-1_1.
Testo completoAbstract (sommario):
AbstractCultural heritage objects composed of inorganic materials, such as metals and stones, support microbial life. Many factors affect the growth of microorganisms: moisture, pH, light, temperature, nutrients. Their colonization relates closely to the nature of the substrata as well as to the characteristic of the surrounding environment. This chapter contains an overview of the complex relationships among microbial growth, materials, and the environment. It emphasizes issues on bioreceptivity of stones and the factors influencing biological colonization, focusing on the biological alteration of inorganic heritage objects and on the agents of biodeterioration. It outlines the effect of biofilms and lichens in terms of degradation of substrata and includes a discussion on an important topic, the bioprotection of stones by biofilms and lichens. In summary, this chapter aims to discuss these issues and review the recent literature on (i) biofilms and lichens colonizing inorganic materials, (ii) the limiting factors of this colonization, (iii) the deteriorative aspects, and (iv) the protective effects of the colonization.
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Cappitelli, Francesca, Federica Villa e Andrea Polo. "Culture-Independent Methods to Study Subaerial Biofilm Growing on Biodeteriorated Surfaces of Stone Cultural Heritage and Frescoes". In Methods in Molecular Biology, 341–66. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-0467-9_24.
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King, Rebecca M., e Victoria Korolik. "Characterization of Ligand–Receptor Interactions: Chemotaxis, Biofilm, Cell Culture Assays, and Animal Model Methodologies". In Methods in Molecular Biology, 149–61. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-6536-6_13.
Testo completoAtti di convegni sul tema "Biofilm cultures"
1
Bhaduri, S., S. K. Mitra e A. Kumar. "Understanding Biofilm Growth Dynamics Within a Stagnant Culture of Sporosarcina Pasteurii". In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36778.
Testo completoAbstract (sommario):
Biofilms are bacterial colonies that form at interfaces, where bacteria are encased in extracellular polymeric substances (EPS). Biofilms are ubiquitous in both artificial systems and our environment. Here we focus on understanding biofilm growth within a stagnant pool of confined diluted culture of the bacteria. Sporosarcina pasteurii is taken as the model bacterium for this study. The motivation behind the choice of this organism stems from the fact that S. Pasteurii has the unique ability to precipitate calcite inside the host media which has tremendous applications in reservoir and restoration engineering. As the biofilm evolves with time inside the confinement, the dynamics of transport is recorded continuously by an optical microscope and the data processed digitally to gain valuable insights into the bio-physical aspects of the system.
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Kussovski, V., V. Mantareva, I. Angelov, L. Avramov, E. Popova e S. Dimitrov. "Al(III), Pd(II), and Zn(II) phthalocyanines for inactivation of dental pathogen Aggregatibacter actinomycetemcomitans as planktonic and biofilm-cultures". In SPIE Photonics Europe, a cura di Jürgen Popp, Wolfgang Drexler, Valery V. Tuchin e Dennis L. Matthews. SPIE, 2012. http://dx.doi.org/10.1117/12.923050.
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Zahra, R., A. A. Khan e M. Sajid. "Hydrodynamic Evaluation of Microtiter Plate Assay Using Computational Fluid Dynamics for Biofilm Formation". In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5425.
Testo completoAbstract (sommario):
Abstract Biofilms are complex surface associated communities where bacterial cells are enclosed by self-produced extra cellular polymeric substances (EPS), mainly consisting of exopolysaccharides, proteins and extracellular DNA. Treatment of biofilm associated persistent infections is an emerging issue for clinicians as bacterial cells adhere with human epithelial cells or indwelling medical devices such as implants and catheters, used in urinary tract and respiratory infections. Several methods are in practice to assess the biofilm formation of bacterial strains. Most of these are phenotypic methods which include Congo red assay (CRA), Air liquid interface (ALI), tissue culture plate method and Microtiter plate assay (MTPA). MTPA is considered as a standard screening method for comparing adherence pattern and is the most widely used quantitative method for detection of biofilm formation. Generally, the assay is performed under standard static conditions and little is known about the hydrodynamics in the microtiter plates. A few studies have applied computational fluid dynamics (CFD) simulations to describe flow pattern in microtiter plates during biofilm production and optimized the suitable conditions to detect the biofilm formation which have proven to be efficient. In this work the dependencies of biofilm formation on the hydrodynamics in microtiter plate assays were evaluated using OpenFOAM® an open-source toolbox for numerical simulation. It was found that higher flow rates increase the nutrient availability, promote cell growth, and attachment pattern with increased production of exopolymer, while the increase in flow velocity increases the shear rate causing erosion and disassembly of biofilm production because of detachment from the surface.
4
"Simultaneous Saccharification and Ethanol Fermentation by Co-culture in Biofilm Reactors". In 2016 ASABE International Meeting. American Society of Agricultural and Biological Engineers, 2016. http://dx.doi.org/10.13031/aim.20162456278.
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Natalia, Angel Villegas, Arce Miranda Julio Eduardo, Becerra María Cecilia, Baronetti José Luis, Ravetti Soledad, Sotomayor Claudia Elena, Albesa Inés e Paraje María Gabriela. "How different culture conditions affect cellular stresses in the biofilms". In MICROBES IN APPLIED RESEARCH - Current Advances and Challenges. WORLD SCIENTIFIC, 2012. http://dx.doi.org/10.1142/9789814405041_0128.
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HANSEL, EZEQUIEL, Alice Costa Kiperstok, Rodrigo Gomes Guimaraes e Emerson Andrade Sales. "CLAY AS A SUBSTRATUM MATERIAL FOR MICROALGAE BIOFILM CULTIVATION". In I South Florida Congress of Development. CONGRESS PROCEEDINGS I South Florida Congress of Development - 2021, 2021. http://dx.doi.org/10.47172/sfcdv2021-0025.
Testo completoAbstract (sommario):
The production of microalgae faces several obstacles. The bioreactors and processes used today in microalgae cultivation are expensive or lack optimization to scale up. Furthermore, harvesting, concentrating and dewatering, while using a cheap and suitable photobioreactor are the main problems that we need to be overcome to achieve viability in the process. The Clay Ceramic Bioreactor (CCBR) was built using only clay and wood sawdust and was designed to grow an immobilized microalgal biofilm while having almost complete separation from the liquid culture medium, reducing the consumption of water and energy. Results showed that the wood sawdust particle size should be sifted in a mesh size 10 and mixed in a proportion of 33% of sawdust and 67% of red clay and a maximum firing temperature of 900oC. Maximum dry biomass production of 3.71 g.m-2.d-1 was achieved within 7 days of cultivation, with no CO2 addition and a low light intensity of 45 µmol.m?2.s?1. The biomass was harvested through simple scraping. Initial results indicate a great potential for the use of clay as substratum and further tests should be carried out to scale up and optimize microalgae production,
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HANSEL, EZEQUIEL, Alice Costa Kiperstok, Rodrigo Gomes Guimaraes e Emerson Andrade Sales. "CLAY AS A SUBSTRATUM MATERIAL FOR MICROALGAE BIOFILM CULTIVATION". In I South Florida Congress of Development. CONGRESS PROCEEDINGS I South Florida Congress of Development - 2021, 2021. http://dx.doi.org/10.47172/sfcdv2021-0063.
Testo completoAbstract (sommario):
The production of microalgae faces several obstacles. The bioreactors and processes used today in microalgae cultivation are expensive or lack optimization to scale up. Furthermore, harvesting, concentrating and dewatering, while using a cheap and suitable photobioreactor are the main problems that we need to be overcome to achieve viability in the process. The Clay Ceramic Bioreactor (CCBR) was built using only clay and wood sawdust and was designed to grow an immobilized microalgal biofilm while having almost complete separation from the liquid culture medium, reducing the consumption of water and energy. Results showed that the wood sawdust particle size should be sifted in a mesh size 10 and mixed in a proportion of 33% of sawdust and 67% of red clay and a maximum firing temperature of 900oC. Maximum dry biomass production of 3.71 g.m-2.d-1 was achieved within 7 days of cultivation, with no CO2 addition and a low light intensity of 45 µmol.m?2.s?1. The biomass was harvested through simple scraping. Initial results indicate a great potential for the use of clay as substratum and further tests should be carried out to scale up and optimize microalgae production,
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Hassan, Huzairy, Bo Jin, Sheng Dai e Cornelius Ngau. "Formation of industrial mixed culture biofilm in chlorophenol cultivated medium of microbial fuel cell". In 4TH INTERNATIONAL CONFERENCE ON FUNDAMENTAL AND APPLIED SCIENCES (ICFAS2016). Author(s), 2016. http://dx.doi.org/10.1063/1.4968084.
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Endicott-Yazdani, T. R. "Concordance of BioFire Pneumonia Panel with Traditional Respiratory Bacterial Culture Results". In American Thoracic Society 2021 International Conference, May 14-19, 2021 - San Diego, CA. American Thoracic Society, 2021. http://dx.doi.org/10.1164/ajrccm-conference.2021.203.1_meetingabstracts.a3869.
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Utkin, A. B., P. Chaves, L. Fernandes, I. V. Pinto e M. J. Revez. "LIF and SFS Techniques for Early Detection of Biofilms Harmful for Cultural Heritage". In 2018 International Conference Laser Optics (ICLO). IEEE, 2018. http://dx.doi.org/10.1109/lo.2018.8435198.
Testo completoRapporti di organizzazioni sul tema "Biofilm cultures"
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Hutchinson, M. L., J. E. L. Corry e R. H. Madden. A review of the impact of food processing on antimicrobial-resistant bacteria in secondary processed meats and meat products. Food Standards Agency, ottobre 2020. http://dx.doi.org/10.46756/sci.fsa.bxn990.
Testo completoAbstract (sommario):
For meat and meat products, secondary processes are those that relate to the downstream of the primary chilling of carcasses. Secondary processes include maturation chilling, deboning, portioning, mincing and other operations such as thermal processing (cooking) that create fresh meat, meat preparations and ready-to-eat meat products. This review systematically identified and summarised information relating to antimicrobial resistance (AMR) during the manufacture of secondary processed meatand meat products (SPMMP). Systematic searching of eight literature databases was undertaken and the resultantpapers were appraised for relevance to AMR and SPMMP. Consideration was made that the appraisal scores, undertaken by different reviewers, were consistent. Appraisal reduced the 11,000 initially identified documents to 74, which indicated that literature relating to AMR and SPMMP was not plentiful. A wide range of laboratory methods and breakpoint values (i.e. the concentration of antimicrobial used to assess sensitivity, tolerance or resistance) were used for the isolation of AMR bacteria.The identified papers provided evidence that AMR bacteria could be routinely isolated from SPMMP. There was no evidence that either confirmed or refuted that genetic materials capable of increasing AMR in non-AMR bacteria were present unprotected (i.e. outside of a cell or a capsid) in SPMMP. Statistical analyses were not straightforward because different authors used different laboratory methodologies.However, analyses using antibiotic organised into broadly-related groups indicated that Enterobacteriaceaeresistant to third generation cephalosporins might be an area of upcoming concern in SPMMP. The effective treatment of patients infected with Enterobacteriaceaeresistant to cephalosporins are a known clinical issue. No AMR associations with geography were observed and most of the publications identified tended to be from Europe and the far east.AMR Listeria monocytogenes and lactic acid bacteria could be tolerant to cleaning and disinfection in secondary processing environments. The basis of the tolerance could be genetic (e.g. efflux pumps) or environmental (e.g. biofilm growth). Persistent, plant resident, AMR L. monocytogenes were shown by one study to be the source of final product contamination. 4 AMR genes can be present in bacterial cultures used for the manufacture of fermented SPMMP. Furthermore, there was broad evidence that AMR loci could be transferred during meat fermentation, with refrigeration temperatures curtailing transfer rates. Given the potential for AMR transfer, it may be prudent to advise food business operators (FBOs) to use fermentation starter cultures that are AMR-free or not contained within easily mobilisable genetic elements. Thermal processing was seen to be the only secondary processing stage that served as a critical control point for numbers of AMR bacteria. There were significant linkages between some AMR genes in Salmonella. Quaternary ammonium compound (QAC) resistance genes were associated with copper, tetracycline and sulphonamide resistance by virtue of co-location on the same plasmid. No evidence was found that either supported or refuted that there was any association between AMR genes and genes that encoded an altered stress response or enhanced the survival of AMR bacteria exposed to harmful environmental conditions.
2
Fields, Matthew W. Identification of Molecular and Cellular Responses of Desulfovibrio vulgaris Biofilms under Culture Conditions Relevant to Field Conditions for Bioreduction. Office of Scientific and Technical Information (OSTI), giugno 2006. http://dx.doi.org/10.2172/896800.
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Wall, Judy D. Identification of Molecular and Cellular Responses of Desulfovibrio vulgaris Biofilms under Culture Conditions Relevant to Field Conditions for Bioreduction of. Office of Scientific and Technical Information (OSTI), giugno 2006. http://dx.doi.org/10.2172/896801.
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Judy D. Wall. Identification of Molecular and Cellular Responses of Desulfovibrio vulgaris Biofilms under Culture Conditions Relevant to Field Conditions for Bioreduction of Toxic Metals and Radionuclides. Office of Scientific and Technical Information (OSTI), giugno 2011. http://dx.doi.org/10.2172/1015868.
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