Log in

Relevant bibliographies by topics / Chemostat / Journal articles

To see the other types of publications on this topic, follow the link: Chemostat.

Journal articles on the topic 'Chemostat'

Author: Grafiati

Published: 4 June 2021

Last updated: 20 February 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Chemostat.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Muñoz-Aguayo, Jeannette, Kevin S. Lang, Timothy M. LaPara, Gerardo González, and Randall S. Singer. "Evaluating the Effects of Chlortetracycline on the Proliferation of Antibiotic-Resistant Bacteria in a Simulated River Water Ecosystem." Applied and Environmental Microbiology 73, no. 17 (July 6, 2007): 5421–25. http://dx.doi.org/10.1128/aem.00708-07.

Full text

Abstract:

ABSTRACT Antibiotics and antibiotic metabolites have been found in the environment, but the biological activities of these compounds are uncertain, especially given the low levels that are typically detected in the environment. The objective of this study was to estimate the selection potential of chlortetracycline (CTC) on the antibiotic resistance of aerobic bacterial populations in a simulated river water ecosystem. Six replicates of a 10-day experiment using river water in continuous flow chemostat systems were conducted. Each replicate used three chemostats, one serving as a control to which no antibiotic was added and the other two receiving low and high doses of CTC (8 μg/liter and 800 μg/liter, respectively). The addition of CTC to the chemostats did not impact the overall level of cultivable aerobic bacteria (P = 0.51). The high-CTC chemostat had significantly higher tetracycline-resistant bacterial colony counts than both the low-CTC and the control chemostats (P < 0.035). The differences in resistance between the low-CTC and control chemostats were highly nonsignificant (P = 0.779). In general a greater diversity of tet resistance genes was detected in the high-CTC chemostat and with a greater frequency than in the low-CTC and control chemostats. Low levels of CTC in this in vitro experiment did not select for increased levels of tetracycline resistance among cultivable aerobic bacteria. This finding should not be equated with the absence of environmental risk, however. Low concentrations of antibiotics in the environment may select for resistant bacterial populations once they are concentrated in sediments or other locations.

APA, Harvard, Vancouver, ISO, and other styles

2

Brauer, Matthew J., Alok J. Saldanha, Kara Dolinski, and David Botstein. "Homeostatic Adjustment and Metabolic Remodeling in Glucose-limited Yeast Cultures." Molecular Biology of the Cell 16, no. 5 (May 2005): 2503–17. http://dx.doi.org/10.1091/mbc.e04-11-0968.

Full text

Abstract:

We studied the physiological response to glucose limitation in batch and steady-state (chemostat) cultures of Saccharomyces cerevisiae by following global patterns of gene expression. Glucose-limited batch cultures of yeast go through two sequential exponential growth phases, beginning with a largely fermentative phase, followed by an essentially completely aerobic use of residual glucose and evolved ethanol. Judging from the patterns of gene expression, the state of the cells growing at steady state in glucose-limited chemostats corresponds most closely with the state of cells in batch cultures just before they undergo this “diauxic shift.” Essentially the same pattern was found between chemostats having a fivefold difference in steady-state growth rate (the lower rate approximating that of the second phase respiratory growth rate in batch cultures). Although in both cases the cells in the chemostat consumed most of the glucose, in neither case did they seem to be metabolizing it primarily through respiration. Although there was some indication of a modest oxidative stress response, the chemostat cultures did not exhibit the massive environmental stress response associated with starvation that also is observed, at least in part, during the diauxic shift in batch cultures. We conclude that despite the theoretical possibility of a switch to fully aerobic metabolism of glucose in the chemostat under conditions of glucose scarcity, homeostatic mechanisms are able to carry out metabolic adjustment as if fermentation of the glucose is the preferred option until the glucose is entirely depleted. These results suggest that some aspect of actual starvation, possibly a component of the stress response, may be required for triggering the metabolic remodeling associated with the diauxic shift.

APA, Harvard, Vancouver, ISO, and other styles

3

O'Connell, Heather A., Greg S. Kottkamp, James L. Eppelbaum, Bryan A. Stubblefield, Sarah E. Gilbert, and Eric S. Gilbert. "Influences of Biofilm Structure and Antibiotic Resistance Mechanisms on Indirect Pathogenicity in a Model Polymicrobial Biofilm." Applied and Environmental Microbiology 72, no. 7 (July 2006): 5013–19. http://dx.doi.org/10.1128/aem.02474-05.

Full text

Abstract:

ABSTRACT Indirect pathogenicity (IP), the commensal protection of antibiotic-sensitive pathogens by resistant microorganisms of low intrinsic virulence, can prevent the eradication of polymicrobial infections. The contributions of antibiotic resistance mechanisms and biofilm structure to IP within polymicrobial biofilms were investigated using a model two-member consortium. Escherichia coli ATCC 33456 was transformed with vectors conferring either ampicillin or spectinomycin resistance, creating two distinct populations with different resistance mechanisms. Each strain alone or the consortium was grown as biofilms in flow cells and planktonically in chemostats. Comparisons in survival and activity were made on the basis of MICs and minimum biofilm preventative concentrations, a newly introduced descriptor. In ampicillin-containing medium, commensal interactions were evident during both modes of cultivation, but the sensitive strain experienced a greater benefit in the chemostat, indicating that the biofilm environment limited the commensal interaction between the Ampr and Sptr strains. In spectinomycin-containing medium, growth of the sensitive strain in chemostats and biofilms was not aided by the resistant strain. However, green fluorescent protein expression by the sensitive strain was greater in mixed-population biofilms (9% ± 1%) than when the strain was grown alone (2% ± 0%). No comparable benefit was evident during growth in the chemostat, indicating that the biofilm structure contributed to enhanced activity of the sensitive strain.

APA, Harvard, Vancouver, ISO, and other styles

4

Ogden, Adam, Michael Kuhn, Michael Dority, Susan Buist, Shawn Mehrens, Tong Zhu, Deqing Xiao, J. Richard Miller, and Debra Hanna. "Evaluation of Pharmacokinetic/Pharmacodynamic Relationships of PD-0162819, a Biotin Carboxylase Inhibitor Representing a New Class of Antibacterial Compounds, UsingIn VitroInfection Models." Antimicrobial Agents and Chemotherapy 56, no. 1 (October 10, 2011): 124–29. http://dx.doi.org/10.1128/aac.00090-11.

Full text

Abstract:

ABSTRACTThe present study investigated the pharmacokinetic/pharmacodynamic (PK/PD) relationships of a prototype biotin carboxylase (BC) inhibitor, PD-0162819, againstHaemophilus influenzae3113 in static concentration time-kill (SCTK) and one-compartment chemostatin vitroinfection models.H. influenzae3113 was exposed to PD-0162819 concentrations of 0.5 to 16× the MIC (MIC = 0.125 μg/ml) and area-under-the-curve (AUC)/MIC ratios of 1 to 1,100 in SCTK and chemostat experiments, respectively. Serial samples were collected over 24 h. For efficacy driver analysis, a sigmoid maximum-effect (Emax) model was fitted to the relationship between bacterial density changes over 24 h and corresponding PK/PD indices. A semimechanistic PK/PD model describing the time course of bacterial growth and death was developed. The AUC/MIC ratio best explained efficacy (r2= 0.95) compared to the peak drug concentration (Cmax)/MIC ratio (r2= 0.76) and time above the MIC (T>MIC) (r2= 0.88). Static effects and 99.9% killing were achieved at AUC/MIC values of 500 and 600, respectively. For time course analysis, the net bacterial growth rate constant, maximum bacterial density, and maximum kill rate constant were similar in SCTK and chemostat studies, but PD-0162819 was more potent in SCTK than in the chemostat (50% effective concentration [EC50] = 0.046 versus 0.34 μg/ml). In conclusion, basic PK/PD relationships for PD-0162819 were established usingin vitrodynamic systems. Although the bacterial growth parameters and maximum drug effects were similar in SCTK and the chemostat system, PD-0162819 appeared to be more potent in SCTK, illustrating the importance of understanding the differences in preclinical models. Additional studies are needed to determine thein vivorelevance of these results.

APA, Harvard, Vancouver, ISO, and other styles

5

Ratsak, C. H., B. W. Kooi, and H. W. van Verseveld. "Biomass Reduction and Mineralization Increase Due to the Ciliate Tetrahymena pyriformis Grazing on the Bacterium Pseudomonas fluorescens." Water Science and Technology 29, no. 7 (April 1, 1994): 119–28. http://dx.doi.org/10.2166/wst.1994.0322.

Full text

Abstract:

The currently high sludge production and increasing processing costs call for waste-water treatment plants with high purification efficiency and low biomass production. We studied the latter issue through two-stage chemostat cascades to assess the overall biomass reduction due to ciliate grazing. The bacteria were cultured in the first chemostat whereas the ciliates, grazing on the bacteria from the first chemostat, were cultured in the second chemostat. Mathematical modelling was used to describe the bacteria/ciliate dynamics and some of the growth parameters were fitted. In the second chemostat 22-44% of the carbon originating from the first chemostat was mineralized to CO2. An extra biomass reduction of 12-43% was possible due to grazing by the ciliates. At lower growth rates of the ciliates the extra biomass reduction was higher than at high growth rates. This finding is auspicious, suggesting that predator organisms indeed can reduce sludge production.

APA, Harvard, Vancouver, ISO, and other styles

6

Beste, D. J. V., J. Peters, T. Hooper, C. Avignone-Rossa, M. E. Bushell, and J. McFadden. "Compiling a Molecular Inventory for Mycobacterium bovis BCG at Two Growth Rates: Evidence for Growth Rate-Mediated Regulation of Ribosome Biosynthesis and Lipid Metabolism." Journal of Bacteriology 187, no. 5 (March 1, 2005): 1677–84. http://dx.doi.org/10.1128/jb.187.5.1677-1684.2005.

Full text

Abstract:

ABSTRACT An experimental system of Mycobacterium tuberculosis growth in a carbon-limited chemostat has been established by the use of Mycobacterium bovis BCG as a model organism. For this model, carbon-limited chemostats with low concentrations of glycerol were used to simulate possible growth rates during different stages of tuberculosis. A doubling time of 23 h (D = 0.03 h−1) was adopted to represent cells during the acute phase of infection, whereas a lower dilution rate equivalent to a doubling time of 69 h (D = 0.01 h−1) was used to model mycobacterial persistence. This chemostat model allowed the specific response of the mycobacterial cell to carbon limitation at different growth rates to be elucidated. The macromolecular (RNA, DNA, carbohydrate, and lipid) and elemental (C, H, and N) compositions of the biomass were determined for steady-state cultures, revealing that carbohydrates and lipids comprised more than half of the dry mass of the BCG cell, with only a quarter of the dry weight consisting of protein and RNA. Consistent with studies of other bacteria, the specific growth rate impacts on the macromolecular content of BCG and the proportions of lipid, RNA, and protein increased significantly with the growth rate. The correlation of RNA content with the growth rate indicates that ribosome production in carbon-limited M. bovis BCG cells is subject to growth rate-dependent control. The results also clearly show that the proportion of lipids in the mycobacterial cell is very sensitive to changes in the growth rate, probably reflecting changes in the amounts of storage lipids. Finally, this study demonstrates the utility of the chemostat model of mycobacterial growth for functional genomic, physiology, and systems biology studies.

APA, Harvard, Vancouver, ISO, and other styles

7

Wong, A. D., and C. D. Goldsmith. "The Impact of a Chemostat Discharge Containing Oil Degrading Bacteria on the Biological Kinetics of a Refinery Activated Sludge Process." Water Science and Technology 20, no. 11-12 (November 1, 1988): 131–36. http://dx.doi.org/10.2166/wst.1988.0276.

Full text

Abstract:

The effect of discharging specific oil degrading bacteria from a chemostat to a refinery activated sludge process was determined biokinetically. Plant data for the kinetic evaluation of the waste treatment plant was collected before and during treatment. During treatment, the 500 gallon chemostatic growth chamber was operated on an eight hour hydraulic retention time, at a neutral pH, and was fed a mixture of refinery wastewater and simple sugars. The biokinetic constants k (days−1), Ks (mg/L), and K (L/mg-day) were determined before and after treatment by Monod and Lineweaver-Burk plots. Solids discharged and effluent organic concentrations were also evaluated against the mean cell retention time (MCRT). The maximum utilization rate, k, was found to increase from 0.47 to 0.95 days−1 during the operation of the chemostat. Subsequently, Ks increased from 141 to 556 mg/L. Effluent solids were shown to increase slightly with treatment. However, this was acceptable due to the polishing pond and the benefit of increased ability to accept shock loads of oily wastewater. The reason for the increased suspended solids in the effluent was most likely due to the continual addition of bacteria in exponential growth that were capable of responding to excess substrate. The effect of the chemostatic addition of specific microbial inocula to the refinery waste treatment plant has been to improve the overall organic removal capacity along with subsequent gains in plant stability.

APA, Harvard, Vancouver, ISO, and other styles

8

Zhao, Dianli, Sanling Yuan, and Haidong Liu. "Stochastic dynamics of the delayed chemostat with Lévy noises." International Journal of Biomathematics 12, no. 05 (July 2019): 1950056. http://dx.doi.org/10.1142/s1793524519500566.

Full text

Abstract:

This paper formulates and studies a delayed chemostat with Lévy noises. Existence of the globally positive solution is proved first by establishing suitable Lyapunov functions, and a further result on exact Lyapunov exponent shows the growth of the total concentration in the chemostat. Then, we prove existence of the uniquely ergodic stationary distribution for a subsystem of the nutrient, based on this, a unique threshold is identified, which completely determines persistence or not of the microorganism in the chemostat. Besides, recurrence is studied under special conditions in case that the microorganism persists. Results indicate that all the noises have negative effects on persistence of the microorganism, and the time delay has almost no effects on the sample Lyapunov exponent and the threshold value of the chemostat.

APA, Harvard, Vancouver, ISO, and other styles

9

McDonald, Ian J., Teena Walker, Byron F. Johnson, Antonio J. Aveledo, and C. Stan Tsai. "Effects of ethanol and acetate on glucose-limited chemostat cultures of Schizosaccharomyces pombe, a fission yeast." Canadian Journal of Microbiology 33, no. 7 (July 1, 1987): 598–601. http://dx.doi.org/10.1139/m87-104.

Full text

Abstract:

Glucose-limited chemostat cultures of Schizosaccharomyces pombe were studied to assess metabolic changes induced by the presence of ethanol and acetate. Both ethanol and acetate were utilized by the chemostat cultures. Ethanol increased the maintenance rate of glucose assimilation. Acetate reduced the maintenance rate of glucose consumption and cell counts without significantly affecting the glucose requirements for growth and cell yield. Ethanol accumulation in the chemostat cultures was facilitated by high dilution rates and noninhibitory concentrations of acetate.

APA, Harvard, Vancouver, ISO, and other styles

10

MacNicol, Jennifer L., Simone Renwick, Caroline M. Ganobis, Emma Allen-Vercoe, Jeffery Scott Weese, and Wendy Pearson. "A Comparison of Methods to Maintain the Equine Cecal Microbial Environment In Vitro Utilizing Cecal and Fecal Material." Animals 12, no. 15 (August 8, 2022): 2009. http://dx.doi.org/10.3390/ani12152009.

Full text

Abstract:

The equine gastrointestinal (GI) microbiota is intimately related to the horse. The objective of the current study was to evaluate the microbiome and metabolome of cecal inoculum maintained in an anaerobic chamber or chemostat batch fermenter, as well as the fecal slurry maintained in an anaerobic chamber over 48 h. Cecal and fecal content were collected from healthy adult horses immediately upon death. Cecal fluid was used to inoculate chemostat vessels (chemostat cecal, n = 11) and vessels containing cecal fluid (anaerobic cecal, n = 15) or 5% fecal slurry (anaerobic fecal, n = 6) were maintained in an anaerobic chamber. Sampling for microbiome and metabolome analysis was performed at vessel establishment (0 h), and after 24 h and 48 h of fermentation. Illumina sequencing was performed, and metabolites were identified via nuclear magnetic resonance (NMR). Alpha and beta diversity indices, as well as individual metabolite concentrations and metabolite regression equations, were analyzed and compared between groups and over time. No differences were evident between alpha or beta diversity in cecal fluid maintained in either an anaerobic chamber or chemostat. The microbiome of the fecal inoculum maintained anaerobically shifted over 48 h and was not comparable to that of the cecal inoculum. Metabolite concentrations were consistently highest in chemostat vessels and lowest in anaerobic fecal vessels. Interestingly, the rate of metabolite change in anaerobic cecal and chemostat cecal vessels was comparable. In conclusion, maintaining an equine cecal inoculum in either an anaerobic chamber or chemostat vessel for 48 h is comparable in terms of the microbiome. However, the microbiome and metabolome of fecal material is not comparable with a cecal inoculum. Future research is required to better understand the factors that influence the level of microbial activity in vitro, particularly when microbiome data identify analogous communities.

APA, Harvard, Vancouver, ISO, and other styles

11

BLACK, D. GLENN, FEDERICO HARTE, and P. MICHAEL DAVIDSON. "Escherichia coli Thermal Inactivation Relative to Physiological State." Journal of Food Protection 72, no. 2 (February 1, 2009): 399–402. http://dx.doi.org/10.4315/0362-028x-72.2.399.

Full text

Abstract:

Studies have explored the use of various nonlinear regression techniques to better describe shoulder and/or tailing effects in survivor curves. Researchers have compiled and developed a number of diverse models for describing microbial inactivation and presented goodness of fit analysis to compare them. However, varying physiological states of microorganisms could affect the measured response in a particular population and add uncertainty to results from predictive models. The objective of this study was to determine if the shape and magnitude of the survivor curve are possibly the result of the physiological state, relative to growth conditions, of microbial cells at the time of heat exposure. Inactivation tests were performed using Escherichia coli strain K-12 in triplicate for three growth conditions: statically grown cells, chemostat-grown cells, and chemostat-grown cells with buffered (pH 6.5) feed media. Chemostat cells were significantly less heat resistant than the static or buffered chemostat cells at 58°C. Regression analysis was performed using the GInaFiT freeware tool for Microsoft Excel. A nonlinear Weibull model, capable of fitting tailing effects, was effective for describing both the static and buffered chemostat cells. The log-linear response best described inactivation of the nonbuffered chemostat cells. Results showed differences in the inactivation response of microbial cells depending on their physiological state. The use of any model should take into consideration the proper use of regression tools for accuracy and include a comprehensive understanding of the growth and inactivation conditions used to generate thermal inactivation data.

APA, Harvard, Vancouver, ISO, and other styles

12

Hoshi, K., and H. Deguchi. "The characteristics of the biofilm fixed inside porous medium by sequencing batch reactor." Water Science and Technology 46, no. 1-2 (July 1, 2002): 261–65. http://dx.doi.org/10.2166/wst.2002.0487.

Full text

Abstract:

The fixed biomass inside porous medium has two layers where biomass yield constants are different from each other when it is cultivated in the chemostat reactor. The biomass fixed inside porous medium is tested to see whether the operation type affected the structure of it. Two kinds of operation method of the reactor were used for the biofilm cultivation. One is the batch reactor. Another is the chemostat reactor. From the kinetic test, it is found that the biofilm fixed in the batch reactor does not have two layers that were observed in the biofilm from the chemostat reactor. Within the experimental conditions for type-1, the result of kinetic tests show homogeneous biofilm characteristics. It can be concluded that the reactor type (batch type or chemostat type) affects the structure of biomass fixed inside porous medium.

APA, Harvard, Vancouver, ISO, and other styles

13

Li, Yanqiu. "HOPF bifurcation of the chemostat with delay and simplified holling type-iv response function." MATEC Web of Conferences 309 (2020): 04020. http://dx.doi.org/10.1051/matecconf/202030904020.

Full text

Abstract:

In this paper, the author investigates Chemostat with Delay and Simplifified Holling Type-IV Response Function, which more match the actual meaning in the chemostat system. Using bifurcation theory, we discuss the hopf bifurcation stability in detail.

APA, Harvard, Vancouver, ISO, and other styles

14

Çinar, Ö., T. Deniz, and C. P. L. Grady. "Effect of oxygen on the stability and inducibility of the biodegradative capability of benzoate." Water Science and Technology 48, no. 8 (November 1, 2003): 247–54. http://dx.doi.org/10.2166/wst.2003.0475.

Full text

Abstract:

Anoxic zones in biological nitrogen removal systems are typically open to the atmosphere and receive oxygen from the atmosphere and the recirculation flow from the aerobic zone. This raises the question of how such oxygen input might influence the stability and inducibility of the enzyme systems involved in biodegradation of aromatic compounds. To investigate this, various amounts of oxygen were added to mixed culture denitrifying chemostats receiving benzoate at 667 mg/h as chemical oxygen demand (COD), and the stability and inducibility of the culture’s benzoate biodegradative capability (BBC) were tested in aerobic and anoxic fed-batch reactors (FBRs). Cultures from chemostats receiving oxygen at 0, 33, 133, 266, and 466 mg O2/h lost almost all of their anoxic BBC within one hour after being transferred to an aerobic FBR and the first three cultures did not recover it upon being returned to anoxic conditions. The last two cultures recovered their anoxic BBC between 9 and 16 h during the 16 h aerobic exposure period that preceded their return to anoxic conditions and continued to increase their anoxic BBC as they were retained under anoxic conditions. In contrast, the culture from a chemostat receiving oxygen at 67 mg O2/h retained its anoxic BBC longer, recovered it within 3 h after its return to anoxic conditions, and increased it linearly thereafter. None of the cultures developed any aerobic BBC during the 16 h aerobic exposure period in FBRs. The results suggest that higher oxygen inputs into anoxic reactors helped the mixed microbial cultures recover and/or induced anoxic BBC more easily when they were exposed to alternating aerobic/anoxic environments. The exceptional behavior of the culture from the chemostat receiving oxygen at a rate of 67 mg O2/h may have been caused by the presence of a protective mechanism against the toxic forms of oxygen.

APA, Harvard, Vancouver, ISO, and other styles

15

Frigon, Dominic, Gerard Muyzer, Mark van Loosdrecht, and Lutgarde Raskin. "rRNA and Poly-β-Hydroxybutyrate Dynamics in Bioreactors Subjected to Feast and Famine Cycles." Applied and Environmental Microbiology 72, no. 4 (April 2006): 2322–30. http://dx.doi.org/10.1128/aem.72.4.2322-2330.2006.

Full text

Abstract:

ABSTRACT Feast and famine cycles are common in activated sludge wastewater treatment systems, and they select for bacteria that accumulate storage compounds, such as poly-β-hydroxybutyrate (PHB). Previous studies have shown that variations in influent substrate concentrations force bacteria to accumulate high levels of rRNA compared to the levels in bacteria grown in chemostats. Therefore, it can be hypothesized that bacteria accumulate more rRNA when they are subjected to feast and famine cycles. However, PHB-accumulating bacteria can form biomass (grow) throughout a feast and famine cycle and thus have a lower peak biomass formation rate during the cycle. Consequently, PHB-accumulating bacteria may accumulate less rRNA when they are subjected to feast and famine cycles than bacteria that are not capable of PHB accumulation. These hypotheses were tested with Wautersia eutropha H16 (wild type) and W. eutropha PHB-4 (a mutant not capable of accumulating PHB) grown in chemostat and semibatch reactors. For both strains, the cellular RNA level was higher when the organism was grown in semibatch reactors than when it was grown in chemostats, and the specific biomass formation rates during the feast phase were linearly related to the cellular RNA levels for cultures. Although the two strains exhibited maximum uptake rates when they were grown in semibatch reactors, the wild-type strain responded much more rapidly to the addition of fresh medium than the mutant responded. Furthermore, the chemostat-grown mutant culture was unable to exhibit maximum substrate uptake rates when it was subjected to pulse-wise addition of fresh medium. These data show that the ability to accumulate PHB does not prevent bacteria from accumulating high levels of rRNA when they are subjected to feast and famine cycles. Our results also demonstrate that the ability to accumulate PHB makes the bacteria more responsive to sudden increases in substrate concentrations, which explains their ecological advantage.

APA, Harvard, Vancouver, ISO, and other styles

16

Notley-McRobb, Lucinda, Rachel Pinto, Shona Seeto, and Thomas Ferenci. "Regulation of mutY and Nature of Mutator Mutations in Escherichia coli Populations under Nutrient Limitation." Journal of Bacteriology 184, no. 3 (February 1, 2002): 739–45. http://dx.doi.org/10.1128/jb.184.3.739-745.2002.

Full text

Abstract:

ABSTRACT Previous analysis of aerobic, glucose-limited continuous cultures of Escherichia coli revealed that G:C-to-T:A (G:C→T:A) transversions were the most commonly occurring type of spontaneous mutation. One possible explanation for the preponderance of these mutations was that nutrient limitation repressed MutY-dependent DNA repair, resulting in increased proportions of G:C→T:A transversions. The regulation of the mutY-dependent DNA repair system was therefore studied with a transcriptional mutY-lacZ fusion recombined into the chromosome. Expression from the mutY promoter was fourfold higher under aerobic conditions than under anaerobic conditions. But mutY expression was higher in glucose- or ammonia-limited chemostats than in nutrient-excess batch culture, so mutY was not downregulated by nutrient limitation. An alternative explanation for the frequency of G:C→T:A transversions was the common appearance of mutY mutator mutations in the chemostat populations. Of 11 chemostat populations screened in detail, six contained mutators, and the mutator mutation in four cultures was located in the region of mutY at 66 min on the chromosome. The spectrum of mutations and rate of mutation in these isolates were fully consistent with a mutY-deficiency in each strain. Based on PCR analysis of the region within and around mutY, isolates from three individual populations contained deletions extending at least 2 kb upstream of mutY and more than 5 kb downstream. In the fourth population, the deletion was even longer, extending at least 5 kb upstream and 5 kb downstream of mutY. The isolation of mutY mutator strains from four independent populations with extensive chromosomal rearrangements suggests that mutY inactivation by deletion is a means of increasing mutation rates under nutrient limitation and explains the observed frequency of G:C→T:A mutations in glucose-limited chemostats.

APA, Harvard, Vancouver, ISO, and other styles

17

Swank, Zoe, and Sebastian J. Maerkl. "CFPU: A Cell-Free Processing Unit for High-Throughput, Automated In Vitro Circuit Characterization in Steady-State Conditions." BioDesign Research 2021 (March 17, 2021): 1–11. http://dx.doi.org/10.34133/2021/2968181.

Full text

Abstract:

Forward engineering synthetic circuits are at the core of synthetic biology. Automated solutions will be required to facilitate circuit design and implementation. Circuit design is increasingly being automated with design software, but innovations in experimental automation are lagging behind. Microfluidic technologies made it possible to perform in vitro transcription-translation (tx-tl) reactions with increasing throughput and sophistication, enabling screening and characterization of individual circuit elements and complete circuit designs. Here, we developed an automated microfluidic cell-free processing unit (CFPU) that extends high-throughput screening capabilities to a steady-state reaction environment, which is essential for the implementation and analysis of more complex and dynamic circuits. The CFPU contains 280 chemostats that can be individually programmed with DNA circuits. Each chemostat is periodically supplied with tx-tl reagents, giving rise to sustained, long-term steady-state conditions. Using microfluidic pulse width modulation (PWM), the device is able to generate tx-tl reagent compositions in real time. The device has higher throughput, lower reagent consumption, and overall higher functionality than current chemostat devices. We applied this technology to map transcription factor-based repression under equilibrium conditions and implemented dynamic gene circuits switchable by small molecules. We expect the CFPU to help bridge the gap between circuit design and experimental automation for in vitro development of synthetic gene circuits.

APA, Harvard, Vancouver, ISO, and other styles

18

Behnke, Sabrina, Albert E. Parker, Dawn Woodall, and Anne K. Camper. "Comparing the Chlorine Disinfection of Detached Biofilm Clusters with Those of Sessile Biofilms and Planktonic Cells in Single- and Dual-Species Cultures." Applied and Environmental Microbiology 77, no. 20 (August 19, 2011): 7176–84. http://dx.doi.org/10.1128/aem.05514-11.

Full text

Abstract:

ABSTRACTAlthough the detachment of cells from biofilms is of fundamental importance to the dissemination of organisms in both public health and clinical settings, the disinfection efficacies of commonly used biocides on detached biofilm particles have not been investigated. Therefore, the question arises whether cells in detached aggregates can be killed with disinfectant concentrations sufficient to inactivate planktonic cells.Burkholderia cepaciaandPseudomonas aeruginosawere grown in standardized laboratory reactors as single species and in coculture. Cluster size distributions in chemostats and biofilm reactor effluent were measured. Chlorine susceptibility was assessed for planktonic cultures, attached biofilm, and particles and cells detached from the biofilm. Disinfection tolerance generally increased with a higher percentage of larger cell clusters in the chemostat and detached biofilm. Samples with a lower percentage of large clusters were more easily disinfected. Thus, disinfection tolerance depended on the cluster size distribution rather than sample type for chemostat and detached biofilm. Intact biofilms were more tolerant to chlorine independent of species. Homogenization of samples led to significantly increased susceptibility in all biofilm samples as well as detached clusters for single-speciesB. cepacia,B. cepaciain coculture, andP. aeruginosain coculture. The disinfection efficacy was also dependent on species composition; coculture was advantageous to the survival of both species when grown as a biofilm or as clusters detached from biofilm but, surprisingly, resulted in a lower disinfection tolerance when they were grown as a mixed planktonic culture.

APA, Harvard, Vancouver, ISO, and other styles

19

Kreikenbohm, R., and E. Bohl. "Bistability in the chemostat." Ecological Modelling 43, no. 3-4 (November 1988): 287–301. http://dx.doi.org/10.1016/0304-3800(88)90009-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Sree Hari Rao, V., and P. Raja Sekhara Rao. "Basic chemostat model revisited." Differential Equations and Dynamical Systems 17, no. 1-2 (April 2009): 3–16. http://dx.doi.org/10.1007/s12591-009-0001-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

El-Owaidy, H., and O. A. El-Leithy. "Persistence in the chemostat." Mathematical Biosciences 101, no. 1 (September 1990): 27–39. http://dx.doi.org/10.1016/0025-5564(90)90100-d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Bhandari, Harish Chandra, and Kanhaiya Jha. "An Analysis of Microbial Population of Chemostat Model in Fuzzy Environment." Nepali Mathematical Sciences Report 36, no. 1-2 (December 31, 2019): 1–10. http://dx.doi.org/10.3126/nmsr.v36i1-2.29965.

Full text

Abstract:

Chemostat is a continuous stirred tank reactor used for continuous microbial biomass production in commercial, medical and other research problems. While modeling real world phenomena through differential equations as backbone of practical problems, we need to introduce various parameters. These parameters may be vague, imprecise and uncertain. To incorporate these uncertainties, the notion of fuzzy differential equations is used in chemostat model as one of the tool. In this paper, we discuss some new results for the stability analysis of chemostat model and the results so obtained are justifiable analytically and verified graphically in fuzzy environment.

APA, Harvard, Vancouver, ISO, and other styles

23

SUN, SHULIN, and XIAOFENG ZHANG. "ASYMPTOTIC BEHAVIOR OF A STOCHASTIC DELAYED CHEMOSTAT MODEL WITH NUTRIENT STORAGE." Journal of Biological Systems 26, no. 02 (June 2018): 225–46. http://dx.doi.org/10.1142/s0218339018500110.

Full text

Abstract:

In this paper, a stochastic delayed chemostat model with nutrient storage is proposed and investigated. First, we state that there is a unique global positive solution for this stochastic system. Second, using the classical approach of Lyapunov function analysis, this stochastic delayed chemostat model is discussed in detail. We establish some sufficient conditions for the extinction of the microorganism, furthermore, we prove that the microorganism will become persistent in the mean in the chemostat under some conditions. Finally, the obtained results are illustrated by computer simulations, and simulation results reveal the effects of time delay on the persistence and extinction of the microorganism.

APA, Harvard, Vancouver, ISO, and other styles

24

Aranda-Olmedo, Isabel, Patricia Marín, Juan L. Ramos, and Silvia Marqués. "Role of the ptsN Gene Product in Catabolite Repression of the Pseudomonas putida TOL Toluene Degradation Pathway in Chemostat Cultures▿." Applied and Environmental Microbiology 72, no. 11 (September 22, 2006): 7418–21. http://dx.doi.org/10.1128/aem.01067-06.

Full text

Abstract:

ABSTRACT The Pseudomonas putida KT2440 TOL upper pathway is repressed under nonlimiting conditions in cells growing in chemostat with succinate as a carbon source. We show that the ptsN gene product IIANtr participates in this repression. Crc, involved in yeast extract-dependent repression in batch cultures, did not influence expression when cells were growing in a chemostat with succinate at maximum rate.

APA, Harvard, Vancouver, ISO, and other styles

25

Haddix, Pryce L., and Robert M. Q. Shanks. "Production of prodigiosin pigment by Serratia marcescens is negatively associated with cellular ATP levels during high-rate, low-cell-density growth." Canadian Journal of Microbiology 66, no. 3 (March 2020): 243–55. http://dx.doi.org/10.1139/cjm-2019-0548.

Full text

Abstract:

Serratia marcescens is a facultatively anaerobic bacterium and the most recognized producer of the hydrophobic pigment prodigiosin. Previous work has shown that prodigiosin both increases ATP production during population lag phase and approximately doubles the stationary-phase cell yield. Here, we employed both batch and chemostat culture methods to investigate prodigiosin’s role during high rate growth at low cell density as peak cellular ATP levels decline. Batch culture experiments utilizing artificial pigment induction showed an ATP reduction during low cell density growth. In addition, pigment induction during fixed growth rate chemostat culture revealed a negative correlation between cellular levels of prodigiosin and ATP (r = −0.95). Variable growth rate chemostat experiments showed an inverse relationship between ATP per cell and prodigiosin per cell during low-density growth but a direct relationship during high-density growth. Rate modeling of chemostat data quantified the pigment’s effect on cellular levels of ATP for both population growth phases. Finally, prodigiosin production in a heterologous bacterium led to ATP decline. These data with intact cells complement the established in vitro proton import function of prodigiosin pigment and may indicate an energy-spilling function during high rate, low cell density growth.

APA, Harvard, Vancouver, ISO, and other styles

26

Probert, H. M., and G. R. Gibson. "Development of a fermentation system to model sessile bacterial populations in the human colon." Biofilms 1, no. 1 (January 2004): 13–19. http://dx.doi.org/10.1017/s1479050503001029.

Full text

Abstract:

A fermentation system was designed to model the human colonic microflora in vitro. The system provided a framework of mucin beads to encourage the adhesion of bacteria, which was encased within a dialysis membrane. The void between the beads was inoculated with faeces from human donors. Water and metabolites were removed from the fermentation by osmosis using a solution of polyethylene glycol (PEG). The system was concomitantly inoculated alongside a conventional single-stage chemostat. Three fermentations were carried out using inocula from three healthy human donors.Bacterial populations from the chemostat and biofilm system were enumerated using fluorescence in situ hybridization. The culture fluid was also analysed for its short-chain fatty acid (SCFA) content. A higher cell density was achieved in the biofilm fermentation system (taking into account the contribution made by the bead-associated bacteria) as compared with the chemostat, owing to the removal of water and metabolites. Evaluation of the bacterial populations revealed that the biofilm system was able to support two distinct groups of bacteria: bacteria growing in association with the mucin beads and planktonic bacteria in the culture fluid. Furthermore, distinct differences were observed between populations in the biofilm fermenter system and the chemostat, with the former supporting higher populations of clostridia and Escherichia coli. SCFA levels were lower in the biofilm system than in the chemostat, as in the former they were removed via the osmotic effect of the PEG. These experiments demonstrated the potential usefulness of the biofilm system for investigating the complexity of the human colonic microflora and the contribution made by sessile bacterial populations.

APA, Harvard, Vancouver, ISO, and other styles

27

Wilhelm, Steven W., and Charles G. Trick. "Effects of vitamin B12 concentration on chemostat cultured Synechococcus sp. strain PCC 7002." Canadian Journal of Microbiology 41, no. 2 (February 1, 1995): 145–51. http://dx.doi.org/10.1139/m95-019.

Full text

Abstract:

The effects of vitamin B12 availability on the physiology of the cyanobacterium Synechococcus sp. strain PCC 7002 were examined in a continuous culture chemostat system. The availability of vitamin B12 within the system was demonstrated to control the cell density and cellular chlorophyll levels under nutrient-limiting conditions. Electron micrographs of vitamin B12 replete and vitamin B12 deficient cyanobacteria indicated that a reduction in vitamin B12 availability induced a loss of thylakoid integrity within the system. Polyacrylamide gel electrophoresis demonstrated that the expression of outer membrane proteins of 95, 70, and 34 kDa was enhanced during vitamin B12 limited growth. Cellular quotients were determined to be a minimum of 256 molecules of vitamin B12/cell to sustain a growth rate of 0.6/day. A comparison with eukaryotic plankton demonstrated that the vitamin B12 requirements of cyanobacteria may be more similar to those of chloroplasts than to those of the entire group of eukaryotic algae.Key words: chemostats, cellular quotients, cyanobacterial physiology, Synechococcus, vitamin B12.

APA, Harvard, Vancouver, ISO, and other styles

28

Hansson, Erika M., Dylan Z. Childs, and Andrew P. Beckerman. "Mesostats—A multiplexed, low-cost, do-it-yourself continuous culturing system for experimental evolution of mesocosms." PLOS ONE 17, no. 7 (July 28, 2022): e0272052. http://dx.doi.org/10.1371/journal.pone.0272052.

Full text

Abstract:

Microbial experimental evolution allows studying evolutionary dynamics in action and testing theory predictions in the lab. Experimental evolution in chemostats (i.e. continuous flow through cultures) has recently gained increased interest as it allows tighter control of selective pressures compared to static batch cultures, with a growing number of efforts to develop systems that are easier and cheaper to construct. This protocol describes the design and construction of a multiplexed chemostat array (dubbed “mesostats”) designed for cultivation of algae in 16 concurrent populations, specifically intended for studying adaptation to herbicides. We also present control data from several experiments run on the system to show replicability, data illustrating the effects of common issues like leaks, contamination and clumps, and outline possible modifications and adaptations of the system for future research.

APA, Harvard, Vancouver, ISO, and other styles

29

Baxley, J. V., and S. B. Robinson. "Coexistence in the unstirred chemostat." Applied Mathematics and Computation 89, no. 1-3 (January 1998): 41–65. http://dx.doi.org/10.1016/s0096-3003(97)81647-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Powell, Godfrey E. "Relaxation times in chemostat culture." Journal of Theoretical Biology 112, no. 3 (February 1985): 589–94. http://dx.doi.org/10.1016/s0022-5193(85)80024-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

De Leenheer, Patrick, and Hal Smith. "Feedback control for chemostat models." Journal of Mathematical Biology 46, no. 1 (January 1, 2003): 48–70. http://dx.doi.org/10.1007/s00285-002-0170-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Waltman, Paul. "Coexistence in chemostat-like models." Rocky Mountain Journal of Mathematics 20, no. 4 (December 1990): 777–807. http://dx.doi.org/10.1216/rmjm/1181073042.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Kerr, Emily O., and Maitreya J. Dunham. "Chemostat Culture for Yeast Physiology." Cold Spring Harbor Protocols 2017, no. 7 (July 2017): pdb.prot089003. http://dx.doi.org/10.1101/pdb.prot089003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Menawat, Anil S., and Jayaram Balachander. "Alternate control structures for chemostat." AIChE Journal 37, no. 2 (February 1991): 302–6. http://dx.doi.org/10.1002/aic.690370220.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Campillo, F., M. Joannides, and I. Larramendy-Valverde. "Stochastic modeling of the chemostat." Ecological Modelling 222, no. 15 (August 2011): 2676–89. http://dx.doi.org/10.1016/j.ecolmodel.2011.04.027.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Beste, D. J. V., E. Laing, B. Bonde, C. Avignone-Rossa, M. E. Bushell, and J. J. McFadden. "Transcriptomic Analysis Identifies Growth Rate Modulation as a Component of the Adaptation of Mycobacteria to Survival inside the Macrophage." Journal of Bacteriology 189, no. 11 (March 23, 2007): 3969–76. http://dx.doi.org/10.1128/jb.01787-06.

Full text

Abstract:

ABSTRACT The adaptation of the tubercle bacillus to the host environment is likely to involve a complex set of gene regulatory events and physiological switches in response to environmental signals. In order to deconstruct the physiological state of Mycobacterium tuberculosis in vivo, we used a chemostat model to study a single aspect of the organism's in vivo state, slow growth. Mycobacterium bovis BCG was cultivated at high and low growth rates in a carbon-limited chemostat, and transcriptomic analysis was performed to identify the gene regulation events associated with slow growth. The results demonstrated that slow growth was associated with the induction of expression of several genes of the dormancy survival regulon. There was also a striking overlap between the transcriptomic profile of BCG in the chemostat model and the response of M. tuberculosis to growth in the macrophage, implying that a significant component of the response of the pathogen to the macrophage environment is the response to slow growth in carbon-limited conditions. This demonstrated the importance of adaptation to a low growth rate to the virulence strategy of M. tuberculosis and also the value of the chemostat model for deconstructing components of the in vivo state of this important pathogen.

APA, Harvard, Vancouver, ISO, and other styles

37

LIU, XIAOJUAN, and SHULIN SUN. "DYNAMICAL BEHAVIOR OF STOCHASTIC COMPETITION BETWEEN PLASMID-BEARING AND PLASMID-FREE ORGANISMS IN A CHEMOSTAT MODEL." Journal of Biological Systems 29, no. 01 (March 2021): 147–67. http://dx.doi.org/10.1142/s0218339021500066.

Full text

Abstract:

In this paper, a model of stochastic competition between plasmid-bearing and plasmid-free organisms in a chemostat is investigated. First, we show that there is a unique global positive solution for the stochastic system. Second, by employing stochastic Lyapunov functions, Itô formula, strong law of large number and some other important inequalities, stochastic characteristics of the stochastic competition chemostat model are studied such as the stochastic asymptotic behaviors of the system. Finally, some numerical simulations are given.

APA, Harvard, Vancouver, ISO, and other styles

38

Lindström, Torsten, and Yuanji Cheng. "A Rosenzweig-MacArthur (1963) Criterion for the Chemostat." Scientific World Journal 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/5626980.

Full text

Abstract:

The Rosenzweig-MacArthur (1963) criterion is a graphical criterion that has been widely used for elucidating the local stability properties of the Gause (1934) type predator-prey systems. It has not been stated whether a similar criterion holds for models with explicit resource dynamics (Kooi et al. (1998)), like the chemostat model. In this paper we use the implicit function theorem and implicit derivatives for proving that a similar graphical criterion holds under chemostat conditions, too.

APA, Harvard, Vancouver, ISO, and other styles

39

Yoon, Sukhwan, Robert A. Sanford, and Frank E. Löffler. "Nitrite Control over Dissimilatory Nitrate/Nitrite Reduction Pathways in Shewanella loihica Strain PV-4." Applied and Environmental Microbiology 81, no. 10 (March 13, 2015): 3510–17. http://dx.doi.org/10.1128/aem.00688-15.

Full text

Abstract:

ABSTRACTShewanella loihicastrain PV-4 harbors both a functional denitrification (NO3−→N2) and a respiratory ammonification (NO3−→NH4+) pathway. Batch and chemostat experiments revealed that NO2−affects pathway selection and the formation of reduced products. Strain PV-4 cells grown with NO2−as the sole electron acceptor produced exclusively NH4+. With NO3−as the electron acceptor, denitrification predominated and N2O accounted for ∼90% of reduced products in the presence of acetylene. Chemostat experiments demonstrated that the NO2−:NO3−ratio affected the distribution of reduced products, and respiratory ammonification dominated at high NO2−:NO3−ratios, whereas low NO2−:NO3−ratios favored denitrification. The NO2−:NO3−ratios affectednirKtranscript abundance, a measure of denitrification activity, in the chemostat experiments, and cells grown at a NO2−:NO3−ratio of 3 had ∼37-fold fewernirKtranscripts per cell than cells grown with NO3−as the sole electron acceptor. In contrast, the transcription ofnrfA, implicated in NO2−-to-NH4+reduction, remained statistically unchanged under continuous cultivation conditions at NO2−:NO3−ratios below 3. At NO2−:NO3−ratios above 3, bothnirKandnrfAtranscript numbers decreased and the chemostat culture washed out, presumably due to NO2−toxicity. These findings implicate NO2−as a relevant modulator of NO3−fate inS. loihicastrain PV-4, and, by extension, suggest that NO2−is a relevant determinant for N retention (i.e., ammonification) versus N loss and greenhouse gas emission (i.e., denitrification).

APA, Harvard, Vancouver, ISO, and other styles

40

Ugalde-Salas, Pablo, Héctor Ramírez C., Jérôme Harmand, and Elie Desmond-Le Quéméner. "Microbial Interactions as Drivers of a Nitrification Process in a Chemostat." Bioengineering 8, no. 3 (February 25, 2021): 31. http://dx.doi.org/10.3390/bioengineering8030031.

Full text

Abstract:

This article deals with the inclusion of microbial ecology measurements such as abundances of operational taxonomic units in bioprocess modelling. The first part presents the mathematical analysis of a model that may be framed within the class of Lotka–Volterra models fitted to experimental data in a chemostat setting where a nitrification process was operated for over 500 days. The limitations and the insights of such an approach are discussed. In the second part, the use of an optimal tracking technique (developed within the framework of control theory) for the integration of data from genetic sequencing in chemostat models is presented. The optimal tracking revisits the data used in the aforementioned chemostat setting. The resulting model is an explanatory model, not a predictive one, it is able to reconstruct the different forms of nitrogen in the reactor by using the abundances of the operational taxonomic units, providing some insights into the growth rate of microbes in a complex community.

APA, Harvard, Vancouver, ISO, and other styles

41

Tai, Siew Leng, Pascale Daran-Lapujade, Michael C. Walsh, Jack T. Pronk, and Jean-Marc Daran. "Acclimation ofSaccharomyces cerevisiaeto Low Temperature: A Chemostat-based Transcriptome Analysis." Molecular Biology of the Cell 18, no. 12 (December 2007): 5100–5112. http://dx.doi.org/10.1091/mbc.e07-02-0131.

Full text

Abstract:

Effects of suboptimal temperatures on transcriptional regulation in yeast have been extensively studied in batch cultures. To eliminate indirect effects of specific growth rates that are inherent to batch-cultivation studies, genome-wide transcriptional responses to low temperatures were analyzed in steady-state chemostats, grown at a fixed specific growth rate (0.03 h−1). Although in vivo metabolic fluxes were essentially the same in cultures grown at 12 and at 30°C, concentrations of the growth-limiting nutrients (glucose or ammonia) were higher at 12°C. This difference was reflected by transcript levels of genes that encode transporters for the growth-limiting nutrients. Several transcriptional responses to low temperature occurred under both nutrient-limitation regimes. Increased transcription of ribosome-biogenesis genes emphasized the importance of adapting protein-synthesis capacity to low temperature. In contrast to observations in cold-shock and batch-culture studies, transcript levels of environmental stress response genes were reduced at 12°C. Transcription of trehalose-biosynthesis genes and intracellular trehalose levels indicated that, in contrast to its role in cold-shock adaptation, trehalose is not involved in steady-state low-temperature adaptation. Comparison of the chemostat-based transcriptome data with literature data revealed large differences between transcriptional reprogramming during long-term low-temperature acclimation and the transcriptional responses to a rapid transition to low temperature.

APA, Harvard, Vancouver, ISO, and other styles

42

Futamata, Hiroyuki, Yayoi Nagano, Kazuya Watanabe, and Akira Hiraishi. "Unique Kinetic Properties of Phenol-Degrading Variovorax Strains Responsible for Efficient Trichloroethylene Degradation in a Chemostat Enrichment Culture." Applied and Environmental Microbiology 71, no. 2 (February 2005): 904–11. http://dx.doi.org/10.1128/aem.71.2.904-911.2005.

Full text

Abstract:

ABSTRACT A chemostat enrichment of soil bacteria growing on phenol as the sole carbon source has been shown to exhibit quite high trichloroethylene (TCE)-degrading activities (H. Futamata, S. Harayama, and K. Watanabe, Appl. Environ. Microbiol. 67:4671-4677, 2001). To identify the bacterial populations responsible for the high TCE-degrading activity, a multidisciplinary survey of the chemostat enrichment was conducted by employing molecular-ecological and culture-dependent approaches. Three chemostat enrichment cultures were newly developed under different phenol-loading conditions (0.25, 0.75, and 1.25 g liter−1 day−1) in this study, and the TCE-degrading activities of the enrichments were measured. Among them, the enrichment at 0.75 g liter−1 day−1 (enrichment 0.75) expressed the highest activity. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments detected a Variovorax ribotype as the strongest band in enrichment 0.75; however, it was not a major ribotype in the other samples. Bacteria were isolated from enrichment 0.75 by direct plating, and their 16S rRNA genes and genes encoding the largest subunit of phenol hydroxylase (LmPHs) were analyzed. Among the bacteria isolated, several strains were affiliated with the genus Variovorax and were shown to have high-affinity-type LmPHs. The LmPH of the Variovorax strains was also detected as the major genotype in enrichment 0.75. Kinetic analyses of phenol and TCE degradation revealed, however, that these strains exhibited quite low affinity for phenol compared to other phenol-degrading bacteria, while they showed quite high specific TCE-degrading activities and relatively high affinity for TCE. Owing to these unique kinetic traits, the Variovorax strains can obviate competitive inhibition of TCE degradation by the primary substrate of the catabolic enzyme (i.e., phenol), contributing to the high TCE-degrading activity of the chemostat enrichments. On the basis of physiological information, mechanisms accounting for the way the Variovorax population overgrew the chemostat enrichment are discussed.

APA, Harvard, Vancouver, ISO, and other styles

43

Chi, Mengnan, and Wencai Zhao. "Dynamical Analysis of Two-Microorganism and Single Nutrient Stochastic Chemostat Model with Monod-Haldane Response Function." Complexity 2019 (March 10, 2019): 1–13. http://dx.doi.org/10.1155/2019/8719067.

Full text

Abstract:

In this paper, we formulate and investigate a two-microorganism and single nutrient chemostat model with Monod-Haldane response function and random perturbation. First, for the corresponding deterministic system, we introduce the conditions of the stability of the equilibrium points. Then, using Lyapunov function and Itô’s formula, we investigate the existence and uniqueness of the global positive solution of the stochastic chemostat model. Furthermore, we explore and obtain the criterions of the extinction and the permanence for the stochastic model. Finally, numerical simulations are carried out to illustrate our main results.

APA, Harvard, Vancouver, ISO, and other styles

44

Savoglidis, Georgios, and Costas Kravaris. "Constant-yield control of the chemostat." IFAC Proceedings Volumes 46, no. 23 (2013): 164–69. http://dx.doi.org/10.3182/20130904-3-fr-2041.00048.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

De Leenheer, Patrick, Jack Dockery, Tomas Gedeon, and Sergei S. Pilyugin. "The chemostat with lateral gene transfer." Journal of Biological Dynamics 4, no. 6 (November 2010): 607–20. http://dx.doi.org/10.1080/17513750903540858.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Yang, Jin, and Guangyao Tang. "Piecewise chemostat model with control strategy." Mathematics and Computers in Simulation 156 (February 2019): 126–42. http://dx.doi.org/10.1016/j.matcom.2018.07.004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Boer, M. P., B. W. Kooi, and S. A. L. M. Kooijman. "Food chain dynamics in the chemostat." Mathematical Biosciences 150, no. 1 (June 1998): 43–62. http://dx.doi.org/10.1016/s0025-5564(98)00010-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Pilyugin, Sergei S., and Paul Waltman. "The Simple Chemostat with Wall Growth." SIAM Journal on Applied Mathematics 59, no. 5 (January 1999): 1552–72. http://dx.doi.org/10.1137/s0036139997326181.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Miller, Aaron W., Emily O. Kerr, and Maitreya J. Dunham. "Assembly of a Mini-Chemostat Array." Cold Spring Harbor Protocols 2017, no. 7 (July 2017): pdb.prot088997. http://dx.doi.org/10.1101/pdb.prot088997.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Payen, Celia, and Maitreya J. Dunham. "Chemostat Culture for Yeast Experimental Evolution." Cold Spring Harbor Protocols 2017, no. 7 (July 2017): pdb.prot089011. http://dx.doi.org/10.1101/pdb.prot089011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!