keyword
MENU ▼
Read by QxMD icon Read
search

chemostat

keyword
https://www.readbyqxmd.com/read/28237996/macromolecular-and-elemental-composition-analyses-of-leuconostoc-mesenteroides-atcc-8293-cultured-in-a-chemostat
#1
Jeongsu Bang, Ling Li, Hyunbin Seong, Ye Won Kwon, Dong-Yup Lee, Nam Soo Han
The cellular composition and metabolic compounds of Leuconostoc mesenteroides ATCC 8293 were analyzed after cultivation in an anaerobic chemostat. Macromolecular composition was 24.4% polysaccharide, 29.7% protein, 7.9% lipid, 2.9% DNA, and 7.4% RNA. Amino acid compositions included large amounts of lysine, glutamic acid, alanine, and leucine. Elements were in order of C > O > N > H > S. The metabolites in chemostat were lactic acid (73.34 mM), acetic acid (7.69 mM), and mannitol (9.93 mM). These data provide a first view of the cellular composition of L...
February 24, 2017: Journal of Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28231156/a-computational-study-of-amensalistic-control-of-listeria-monocytogenes-by-lactococcus-lactis-under-nutrient-rich-conditions-in-a-chemostat-setting
#2
Hassan Khassehkhan, Hermann J Eberl
We study a previously introduced mathematical model of amensalistic control of the foodborne pathogen Listeria monocytogenes by the generally regarded as safe lactic acid bacteria Lactococcus lactis in a chemostat setting under nutrient rich growth conditions. The control agent produces lactic acids and thus affects pH in the environment such that it becomes detrimental to the pathogen while it is much more tolerant to these self-inflicted environmental changes itself. The mathematical model consists of five nonlinear ordinary differential equations for both bacterial species, the concentration of lactic acids, the pH and malate...
September 9, 2016: Foods (Basel, Switzerland)
https://www.readbyqxmd.com/read/28220859/sensitivity-of-chemical-weathering-and-dissolved-carbon-dynamics-to-hydrological-conditions-in-a-typical-karst-river
#3
Jun Zhong, Si-Liang Li, Faxiang Tao, Fujun Yue, Cong-Qiang Liu
To better understand the mechanisms that hydrological conditions control chemical weathering and carbon dynamics in the large rivers, we investigated hydrochemistry and carbon isotopic compositions of dissolved inorganic carbon (DIC) based on high-frequency sampling in the Wujiang River draining the carbonate area in southwestern China. Concentrations of major dissolved solute do not strictly follow the dilution process with increasing discharge, and biogeochemical processes lead to variability in the concentration-discharge relationships...
February 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28220205/global-properties-of-nested-network-model-with-application-to-multi-epitope-hiv-ctl-dynamics
#4
Cameron Browne
Mathematical modeling and analysis can provide insight on the dynamics of ecosystems which maintain biodiversity in the face of competitive and prey-predator interactions. Of primary interests are the underlying structure and features which stabilize diverse ecological networks. Recently Korytowski and Smith (Theor Ecol 8(1):111-120, 2015) proved that a perfectly nested infection network, along with appropriate life history trade-offs, leads to coexistence and persistence of bacteria-phage communities in a chemostat model...
February 20, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28212840/a-density-dependent-model-of-competition-for-one-resource-in-the-chemostat
#5
Radhouane Fekih-Salem, Claude Lobry, Tewfik Sari
This paper deals with a two-microbial species model in competition for a single-resource in the chemostat including general intra- and interspecific density-dependent growth rates with distinct removal rates for each species. In order to understand the effects of intra- and interspecific interference, this general model is first studied by determining the conditions of existence and local stability of steady states. With the same removal rate, the model can be reduced to a planar system and then the global stability results for each steady state are derived...
February 14, 2017: Mathematical Biosciences
https://www.readbyqxmd.com/read/28163782/coupling-and-uncoupling-of-triglyceride-and-beta-carotene-production-by-dunaliella-salina-under-nitrogen-limitation-and-starvation
#6
Hubert Bonnefond, Nina Moelants, Amélie Talec, Patrick Mayzaud, Olivier Bernard, Antoine Sciandra
BACKGROUND: Nitrogen starvation and limitation are known to induce important physiological changes especially in lipid metabolism of microalgae (triglycerides, membrane lipids, beta-carotene, etc.). Although little information is available for Dunaliella salina, it is a promising microalga for biofuel production and biotechnological applications due to its ability to accumulate lipid together with beta-carotene. RESULTS: Batch and chemostat experiments with various degrees of nitrogen limitation, ranging from starvation to nitrogen-replete conditions, were carried out to study carbon storage dynamics (total carbon, lipids, and beta-carotene) in steady state cultures of D...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/28159643/metabolic-flexibility-of-a-butyrate-pathway-mutant-of-clostridium-acetobutylicum
#7
Minyeong Yoo, Christian Croux, Isabelle Meynial-Salles, Philippe Soucaille
Clostridium acetobutylicum possesses two homologous buk genes, buk (or buk1) and buk2, which encode butyrate kinases involved in the last step of butyrate formation. To investigate the contribution of buk in detail, an in-frame deletion mutant was constructed. However, in all the Δbuk mutants obtained, partial deletions of the upstream ptb gene were observed, and low phosphotransbutyrylase and butyrate kinase activities were measured. This demonstrates that i) buk (CA_C3075) is the key butyrate kinase-encoding gene and that buk2 (CA_C1660) that is poorly transcribed only plays a minor role; and ii) strongly suggests that a Δbuk mutant is not viable if the ptb gene is not also inactivated, probably due to the accumulation of butyryl-phosphate, which might be toxic for the cell...
January 31, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28130571/gaussian-approximations-for-chemostat-models-in-finite-and-infinite-dimensions
#8
Bertrand Cloez, Coralie Fritsch
In a chemostat, bacteria live in a growth container of constant volume in which liquid is injected continuously. Recently, Campillo and Fritsch introduced a mass-structured individual-based model to represent this dynamics and proved its convergence to a more classic partial differential equation. In this work, we are interested in the convergence of the fluctuation process. We consider this process in some Sobolev spaces and use central limit theorems on Hilbert space to prove its convergence in law to an infinite-dimensional Gaussian process...
January 27, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28117390/growth-rate-control-of-flagellar-assembly-in-escherichia-coli-strain-rp437
#9
Martin Sim, Santosh Koirala, David Picton, Henrik Strahl, Paul A Hoskisson, Christopher V Rao, Colin S Gillespie, Phillip D Aldridge
The flagellum is a rotary motor that enables bacteria to swim in liquids and swarm over surfaces. Numerous global regulators control flagellar assembly in response to cellular and environmental factors. Previous studies have also shown that flagellar assembly is affected by the growth-rate of the cell. However, a systematic study has not yet been described under controlled growth conditions. Here, we investigated the effect of growth rate on flagellar assembly in Escherichia coli using steady-state chemostat cultures where we could precisely control the cell growth-rate...
January 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28108307/the-impact-of-a-predator-on-the-outcome-of-competition-in-the-three-trophic-food-web
#10
Partha Sharathi Dutta, Bob W Kooi, Ulrike Feudel
We study the effects of predation on the competition of prey populations for two resources in a chemostat. We investigate a variety of small food web compositions: the bi-trophic food web (two resources-two competing prey) and the three-trophic food web (two resources-two prey-generalist predator) comparing different model formulations: substitutable resources and essential resources, namely Liebig's minimum law model (perfect essential resources) and complementary resources formulations. The prediction of the outcome of competition is solely based on bifurcation analysis in which the inflow of resources into the chemostat is used as the bifurcation parameter...
January 17, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28094795/impacts-of-chemical-gradients-on-microbial-community-structure
#11
Jianwei Chen, Anna Hanke, Halina E Tegetmeyer, Ines Kattelmann, Ritin Sharma, Emmo Hamann, Theresa Hargesheimer, Beate Kraft, Sabine Lenk, Jeanine S Geelhoed, Robert L Hettich, Marc Strous
Succession of redox processes is sometimes assumed to define a basic microbial community structure for ecosystems with oxygen gradients. In this paradigm, aerobic respiration, denitrification, fermentation and sulfate reduction proceed in a thermodynamically determined order, known as the 'redox tower'. Here, we investigated whether redox sorting of microbial processes explains microbial community structure at low-oxygen concentrations. We subjected a diverse microbial community sampled from a coastal marine sediment to 100 days of tidal cycling in a laboratory chemostat...
January 17, 2017: ISME Journal
https://www.readbyqxmd.com/read/28092732/enhancement-of-lipid-productivity-by-adopting-multi-stage-continuous-cultivation-strategy-in-nannochloropsis-gaditana
#12
Min-Gyu Sung, Bongsoo Lee, Chul Woong Kim, Kibok Nam, Yong Keun Chang
In the present study, a novel process-based cultivation system was designed to improve lipid productivity of Nannochloropsis gaditana, an oleaginous microalga that has high potential for biofuel production. Specifically, four flat-panel photobioreactors were connected in series, and this system was subjected to continuous chemostat cultivation by feeding fresh medium to the first reactor at dilution rates of 0.028 and 0.056day(-1), which were determined based on Monod kinetics. The results show that the serially connected photobioreactor system achieved 20...
April 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28079055/intestinal-microbiota-as-a-tetrahydrobiopterin-exogenous-source-in-hph-1-mice
#13
Jaques Belik, Yulia Shifrin, Erland Arning, Teodoro Bottiglieri, Jingyi Pan, Michelle C Daigneault, Emma Allen-Vercoe
Tetrahydrobiopterin (BH4) is a cofactor of a number of regulatory enzymes. Although there are no known BH4 exogenous sources, the tissue content of this biopterin increases with age in GTP cyclohydrolase 1-deficient hyperphenylalaninemia-1 (hph-1) mice. Since certain bacteria are known to generate BH4, we hypothesize that generation of this biopterin by the intestinal microbiota contributes to its tissue increase in hph-1 adult mice. The goal of this study was to comparatively evaluate hph-1 mice and wild-type C57Bl/6 controls for the presence of intestinal BH4-producing bacteria...
January 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28074222/regulation-of-membrane-fixation-and-energy-production-conversion-for-adaptation-and-recovery-of-zno-nanoparticle-impacted-nitrosomonas-europaea
#14
Junkang Wu, Huijie Lu, Guangcan Zhu, Lianghui Chen, Yan Chang, Ran Yu
The ZnO nanoparticle (NP) effects on typical ammonia-oxidizing bacteria, Nitrosomonas europaea in a chemostat bioreactor, and the cells' toxicity adaptation and recovery potentials were explored. Hardly any inhibition was observed when the NP concentration was high up to 10 mg/L. The cells exposed to 50 mg/L ZnO NPs displayed time-dependent impairment and recovery potentials in terms of cell density, membrane integrity, nitrite production rate, and ammonia monooxygenase activity. The 6-h NP stress impaired cells were nearly completely restored during a 12-h recovery incubation, while the longer exposure time would cause irretrievable cell damage...
January 10, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28073397/identification-of-new-members-of-the-escherichia-coli-k-12-mg1655-slya-regulon
#15
Thomas Curran, Fatima Abacha, Stephen Hibberd, Matthew Rolfe, Melissa Lacey, Jeffrey Green
SlyA is a member of the MarR family of bacterial transcriptional regulators. Previously, SlyA has been shown to directly regulate only two operons in Escherichia coli K-12 MG1655, fimB and hlyE (clyA). In both cases SlyA activates gene expression by antagonizing repression by the nucleoid associated protein H-NS. Here the transcript profiles of aerobic glucose-limited steady-state chemostat cultures of E. coli K-12 MG1655, slyA mutant and slyA over-expression strains are reported. The transcript profile of the slyA mutant was not significantly different to that of the parent; however, that of the slyA expression strain was significantly different from that of the vector control...
January 10, 2017: Microbiology
https://www.readbyqxmd.com/read/28072422/the-fitness-costs-and-trade-off-shapes-associated-with-the-exclusion-of-nine-antibiotics-by-ompf-porin-channels
#16
Katherine Phan, Thomas Ferenci
The trade-off relationship between antibiotic exclusion and nutrient access across the Gram-negative outer membrane is determined by structural constraints in porin channels. The precise nutritional cost of exclusion is unknown for different antibiotics, as are the shapes of the nutrition-susceptibility trade-off. Using a library of 10 engineered isogenic Escherichia coli strains with structural modifications of OmpF porin expressed at a constant level, susceptibilities were measured for nine antibiotics and the nutritional fitness costs estimated by competitions in chemostats...
January 10, 2017: ISME Journal
https://www.readbyqxmd.com/read/27995610/growth-rate-and-resource-imbalance-interactively-control-biomass-stoichiometry-and-elemental-quotas-of-aquatic-bacteria
#17
Casey M Godwin, Emily A Whitaker, James B Cotner
The effects of resource stoichiometry and growth rate on the elemental composition of biomass have been examined in a wide variety of organisms, but the interaction among these effects is often overlooked. To determine how growth rate and resource imbalance affect bacterial carbon (C): nitrogen (N): phosphorus (P) stoichiometry and elemental content, we cultured two strains of aquatic heterotrophic bacteria in chemostats at a range of dilution rates and P supply levels (C:P of 100:1 to 10,000:1). When growing below 50% of their maximum growth rate, P availability and dilution rate had strong interactive effects on biomass C:N:P, elemental quotas, cell size, respiration rate, and growth efficiency...
December 19, 2016: Ecology
https://www.readbyqxmd.com/read/27986600/effect-of-culture-residence-time-on-substrate-uptake-and-storage-by-a-pure-culture-of-thiothrix-ct3-strain-under-continuous-or-batch-feeding
#18
Francesco Valentino, Mario Beccari, Marianna Villano, Valter Tandoi, Mauro Majone
A pure culture of the filamentous bacterium Thiothrix, strain CT3, was aerobically cultured in a chemostat under continuous acetate feeding at three different culture residence times (RT 6, 12 or 22 d) and the same volumetric organic load rate (OLR 0.12gCOD/L/d). Cells cultured at decreasing RT in the chemostat had an increasing transient response to acetate spikes in batch tests. The maximum specific acetate removal rate increased from 25 to 185mgCOD/gCOD/h, corresponding to a 1.8 to 8.1 fold higher respective steady-state rate in the chemostat...
May 25, 2017: New Biotechnology
https://www.readbyqxmd.com/read/27974391/quantifying-in-situ-growth-rate-of-a-filamentous-bacterial-species-in-activated-sludge-using-rrna-rdna-ratio
#19
Vivi L Nguyen, Xia He, Francis L de Los Reyes
If the in situ growth rate of filamentous bacteria in activated sludge can be quantified, researchers can more accurately assess the effect of operating conditions on the growth of filaments and improve the mathematical modeling of filamentous bulking. We developed a method to quantify the in situ specific growth rate of Sphaerotilus natans (a model filament) in activated sludge using the species-specific 16S rRNA:rDNA ratio. Primers targeting the 16S rRNA of S. natans were designed, and real-time PCR and RT-PCR were used to quantify DNA and RNA levels of S...
November 2016: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/27933040/dnra-and-denitrification-coexist-over-a-broad-range-of-acetate-n-no3-ratios-in-a-chemostat-enrichment-culture
#20
Eveline M van den Berg, Marissa Boleij, J Gijs Kuenen, Robbert Kleerebezem, Mark C M van Loosdrecht
Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) compete for nitrate in natural and engineered environments. A known important factor in this microbial competition is the ratio of available electron donor and elector acceptor, here expressed as Ac/N ratio (acetate/nitrate-nitrogen). We studied the impact of the Ac/N ratio on the nitrate reduction pathways in chemostat enrichment cultures, grown on acetate mineral medium. Stepwise, conditions were changed from nitrate limitation to nitrate excess in the system by applying a variable Ac/N ratio in the feed...
2016: Frontiers in Microbiology
keyword
keyword
103881
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"