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stress response membrane bacteria

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https://www.readbyqxmd.com/read/28807687/influence-of-tween-80-on-the-production-and-structure-of-water-insoluble-curdlan-from-agrobacterium-sp
#1
Ying Liang, Li Zhu, Minjie Gao, Zhiyong Zheng, Jianrong Wu, Xiaobei Zhan
In order to explore the mechanism by which Tween-80 enhances the production of curdlan produced by Agrobacterium sp., the effects of Tween-80 on the production and structure of curdlan and Agrobacterium sp. were evaluated. Maximum curdlan production (51.94g/L) was achieved when 16g/L Tween-80 was added at the beginning of the cell growth stage. The addition of Tween-80 at higher concentration inhibited cell growth. However, the addition of 16g/L Tween-80 enhanced the production of curdlan with a looser ultrastructure, significantly weakened the envelopment of curdlan on Agrobacterium sp...
August 11, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28795780/pseudomonas-aeruginosa-defense-systems-against-microbicidal-oxidants
#2
Bastian Groitl, Jan-Ulrik Dahl, Jeremy W Schroeder, Ursula Jakob
The most abundant oxidants controlling bacterial colonization on mucosal barrier epithelia are hypochlorous acid (HOCl), hypobromous acid (HOBr), and hypothiocyanous acid (HOSCN). All three oxidants are highly antimicrobial but little is known about their relative efficacies, their respective cellular targets, or what specific responses they elicit in bacteria. To address these important questions, we directly tested the individual oxidants on the virulent Pseudomonas aeruginosa strain PA14. We discovered that HOCl and HOBr work almost interchangeably, impacting non-growing bacterial cultures more significantly than actively growing bacteria, and eliciting similar stress responses, including the heat shock response...
August 10, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28765539/bacterial-membrane-vesicles-transport-their-dna-cargo-into-host-cells
#3
Natalie J Bitto, Ross Chapman, Sacha Pidot, Adam Costin, Camden Lo, Jasmine Choi, Tanya D'Cruze, Eric C Reynolds, Stuart G Dashper, Lynne Turnbull, Cynthia B Whitchurch, Timothy P Stinear, Katryn J Stacey, Richard L Ferrero
Bacterial outer membrane vesicles (OMVs) are extracellular sacs containing biologically active products, such as proteins, cell wall components and toxins. OMVs are reported to contain DNA, however, little is known about the nature of this DNA, nor whether it can be transported into host cells. Our work demonstrates that chromosomal DNA is packaged into OMVs shed by bacteria during exponential phase. Most of this DNA was present on the external surfaces of OMVs, with smaller amounts located internally. The DNA within the internal compartments of Pseudomonas aeruginosa OMVs were consistently enriched in specific regions of the bacterial chromosome, encoding proteins involved in virulence, stress response, antibiotic resistance and metabolism...
August 1, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28760851/a-bacterial-stress-response-regulates-expression-of-respiratory-protein-complexes-to-control-envelope-stress-adaptation
#4
Randi L Guest, Junshu Wang, Julia L Wong, Tracy L Raivio
The Cpx envelope stress response mediates adaptation to stresses that affect protein folding within the envelope of gram-negative bacteria. Recent transcriptome analyses revealed that the Cpx response impacts genes that affect multiple cellular functions predominantly associated with the cytoplasmic membrane. In this study, we examined the connection between the Cpx response and the respiratory complexes NADH dehydrogenase I and cytochrome bo3 in enteropathogenic Escherichia coli We found that the Cpx response directly represses transcription of the nuo and cyo operons and that Cpx-mediated repression of these complexes confers adaptation to stresses that compromise envelope integrity...
July 31, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28747041/influence-of-commercial-inactivated-yeast-derivatives-on-the-survival-of-probiotic-bacterium-lactobacillus-rhamnosus-hn001-in-an-acidic-environment
#5
Mingzhan Toh, Shao Quan Liu
This study evaluated the influence of three inactivated yeast derivatives (IYDs) used in wine production, namely OptiRed(®), OptiWhite(®) and Noblesse(®), on the viability of the probiotic strain Lactobacillus rhamnosus HN001 in an acidic environment. Addition of the IYDs at 3 g/L significantly enhanced the survival of the probiotic bacteria by 2.75-4.05 log cycles after 10-h exposure in a pH 3.0 buffer. Acid stress assay with IYD components obtained after centrifugation and filtration revealed that water-soluble compounds were responsible for improving the acid tolerance of L...
December 2017: AMB Express
https://www.readbyqxmd.com/read/28741415/gram-negative-bacterial-membrane-vesicle-release-in-response-to-the-host-environment-different-threats-same-trick
#6
Charlotte Volgers, Paul H M Savelkoul, Frank R M Stassen
Bacteria are confronted with a multitude of stressors when occupying niches within the host. These stressors originate from host defense mechanisms, other bacteria during niche competition or result from physiological challenges such as nutrient limitation. To counteract these stressors, bacteria have developed a stress-induced network to mount the adaptations required for survival. These stress-induced adaptations include the release of membrane vesicles from the bacterial envelope. Membrane vesicles can provide bacteria with a plethora of immediate and ultimate benefits for coping with environmental stressors...
July 25, 2017: Critical Reviews in Microbiology
https://www.readbyqxmd.com/read/28738514/unraveling-the-impact-of-nanoscale-zero-valent-iron-on-the-nitrogen-removal-performance-and-microbial-community-of-anammox-sludge
#7
Zheng-Zhe Zhang, Jia-Jia Xu, Zhi-Jian Shi, Yu-Hui Bai, Ya-Fei Cheng, Hai-Yan Hu, Ren-Cun Jin
Given the increasing use of nanoscale zero-valent iron (NZVI) particles for environmental remediation and wastewater treatment, their potential impact on anaerobic ammonium oxidation (anammox) bacteria was investigated in this study using anammox sludge. Batch assays showed that NZVI concentrations up to 200mgL(-1) did not affect anammox activity, reactive oxygen species production, and cell membrane integrity. The nitrogen removal efficiency of the continuous-flow reactor fluctuated in the presence of 20 or 50mgL(-1) NZVI, but it could return to normal over time, even at 200mgL(-1) NZVI...
July 11, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28720734/lack-of-acrb-efflux-function-confers-loss-of-virulence-on-salmonella-enterica-serovar-typhimurium
#8
Xuan Wang-Kan, Jessica M A Blair, Barbara Chirullo, Jonathan Betts, Roberto M La Ragione, Alasdair Ivens, Vito Ricci, Timothy J Opperman, Laura J V Piddock
AcrAB-TolC is the paradigm resistance-nodulation-division (RND) multidrug resistance efflux system in Gram-negative bacteria, with AcrB being the pump protein in this complex. We constructed a nonfunctional AcrB mutant by replacing D408, a highly conserved residue essential for proton translocation. Western blotting confirmed that the AcrB D408A mutant had the same native level of expression of AcrB as the parental strain. The mutant had no growth deficiencies in rich or minimal medium. However, compared with wild-type SL1344, the mutant had increased accumulation of Hoechst 33342 dye and decreased efflux of ethidium bromide and was multidrug hypersusceptible...
July 18, 2017: MBio
https://www.readbyqxmd.com/read/28702643/antioxidant-ace-inhibitory-and-antimicrobial-activity-of-fermented-goat-milk-activity-and-physicochemical-property-relationship-of-the-peptide-components
#9
Miriam Moreno-Montoro, Manuel Olalla-Herrera, José Ángel Rufián-Henares, Rafael Giménez Martínez, Beatriz Miralles, Triana Bergillos, Miguel Navarro-Alarcón, Paula Jauregi
Increasing evidence on goat milk and the health benefits of its derived products beyond its nutritional value show its potential as a functional food. In this study, goat milk fractions were tested for their total antioxidant capacity using different methods (ORAC, ABTS, DPPH and FRAP), as well as their angiotensin-I-converting-enzyme inhibitory and antimicrobial (against Escherichia coli and Micrococcus luteus) activities. Different whey fractions (whey, cation exchange membrane permeate P and retentate R) of two fermented skimmed goat milks (ultrafiltered goat milk fermented with the classical starter bacteria or with the classical starter plus the Lactobacillus plantarum C4 probiotic strain) were assessed...
August 1, 2017: Food & Function
https://www.readbyqxmd.com/read/28674071/-major-tom-to-ground-control-how-lipoproteins-communicate-extra-cytoplasmic-stress-to-the-decision-center-of-the-cell
#10
Géraldine Laloux, Jean-François Collet
The envelope of bacteria is a complex multi-layered shield that ensures multiple essential functions, including protecting the cell from external assaults. Hence, bacterial cells have evolved intricate mechanisms, called envelope stress response systems (ESRS), to monitor all kinds of perturbations affecting the integrity of their envelope and mount an appropriate response to contain or repair the damage. In the model bacterium Escherichia coli, several ESRS are built around a two-component system, in which envelope stress triggers a phosphotransfer between a sensor protein in the inner membrane of the envelope and a response regulator in the cytoplasm...
July 3, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28674070/bacillus-subtilis-intramembrane-protease-rasp-activity-in-escherichia-coli-and-in-vitro
#11
Daniel Parrell, Yang Zhang, Sandra Olenic, Lee Kroos
RasP is a predicted intramembrane metalloprotease of Bacillus subtilis that has been proposed to cleave the stress response anti-sigma factors RsiW and RsiV, the cell division protein FtsL, and remnant signal peptides, within their transmembrane segments. To provide evidence for direct effects of RasP on putative substrates, we developed a heterologous coexpression system. Since expression of catalytically-inactive RasP E21A inhibited expression of other membrane proteins in Escherichia coli, we added extra transmembrane segments to RasP E21A, which allowed accumulation of most other membrane proteins...
July 3, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28674068/structural-and-functional-analysis-of-the-escherichia-coli-acid-sensing-histidine-kinase-evgs
#12
Hrishiraj Sen, Nikhil Aggarwal, Chibueze Ishionwu, Nosheen Hussain, Chandni Parmar, Mohammed Jamshad, Vassiliy N Bavro, Peter A Lund
The EvgS/EvgA two component system of E. coli is activated in response to low pH and alkali metals, and regulates many genes including the glutamate dependent acid resistance system and a number of efflux pumps. EvgS, the sensor kinase, is one of five unconventional histidine kinases in E. coli, and has a large periplasmic domain and a cytoplasmic PAS domain in addition to phospho-acceptor, HK and dimerization, internal receiver, and phosphotransfer domains. Mutations that constitutively activate the protein at pH 7 map to the PAS domain...
July 3, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28666873/overexpression-of-mica-induces-production-of-ompc-enriched-outer-membrane-vesicles-that-protect-against-salmonella-challenge
#13
Hyun-Il Choi, Moonjeong Kim, Jinseong Jeon, Jin Kwan Han, Kwang-Sun Kim
Outer membrane vesicles (OMVs) derived from bacteria are promising candidates for subunit vaccines. Stresses that modulate the composition of outer membrane proteins (OMPs) are important for OMV synthesis. Small RNAs (sRNAs) expressed in response to stress regulate OMPs, although the mechanism underlying sRNA-mediated OMV biogenesis and its utility for developing vaccine platforms remains to be elucidated. Here, we characterized the role of a sRNA, MicA, which regulates OmpA, a major OMP involved in both production of OMVs and reactive immunity against Salmonella challenge...
August 26, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28649237/outer-membrane-vesicles-omvs-of-gram-negative-bacteria-a-perspective-update
#14
REVIEW
Arif Tasleem Jan
Outer Membrane Vesicles (OMVs) of Gram-negative bacteria are spherical membrane-enclosed entities of endocytic origin. Reported in the consortia of different bacterial species, production of OMVs into extracellular milieu seems essential for their survival. Enriched with bioactive proteins, toxins, and virulence factors, OMVs play a critical role in the bacteria-bacteria and bacteria-host interactions. Emergence of OMVs as distinct cellular entities helps bacteria in adaptating to diverse niches, in competing with other bacteria to protect members of producer species and more importantly play a crucial role in host-pathogen interaction...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28646114/staphylococcus-aureus-strain-newman-photoinactivation-and-cellular-response-to-sunlight-exposure
#15
Jill S McClary, Lauren M Sassoubre, Alexandria B Boehm
Sunlight influences microbial water quality of surface waters. Previous studies have investigated photoinactivation mechanisms and cellular photostress responses of fecal indicator bacteria (FIB), including Escherichia coli and enterococci, but further work is needed to characterize photostress responses of bacterial pathogens. Here we investigate the photoinactivation of Staphylococcus aureus (strain Newman), a pigmented, waterborne pathogen of emerging concern. We measured photodecay using standard culture-based assays and cellular membrane integrity; and investigated photostress response by measuring the relative number of mRNA transcripts of select oxidative stress, DNA repair, and metabolism genes...
June 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28611746/adaptations-to-high-salt-in-a-halophilic-protist-differential-expression-and-gene-acquisitions-through-duplications-and-gene-transfers
#16
Tommy Harding, Andrew J Roger, Alastair G B Simpson
The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga Dunaliella. By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.e., protozoa...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28607072/adaptor-protein-mediates-dynamic-pump-assembly-for-bacterial-metal-efflux
#17
Ace George Santiago, Tai-Yen Chen, Lauren A Genova, Won Jung, Alayna M George Thompson, Megan M McEvoy, Peng Chen
Multicomponent efflux complexes constitute a primary mechanism for Gram-negative bacteria to expel toxic molecules for survival. As these complexes traverse the periplasm and link inner and outer membranes, it remains unclear how they operate efficiently without compromising periplasmic plasticity. Combining single-molecule superresolution imaging and genetic engineering, we study in living Escherichia coli cells the tripartite efflux complex CusCBA of the resistance-nodulation-division family that is essential for bacterial resistance to drugs and toxic metals...
June 27, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28604884/ferrous-iron-efflux-systems-in-bacteria
#18
REVIEW
Hualiang Pi, John D Helmann
Bacteria require iron for growth, with only a few reported exceptions. In many environments, iron is a limiting nutrient for growth and high affinity uptake systems play a central role in iron homeostasis. However, iron can also be detrimental to cells when it is present in excess, particularly under aerobic conditions where its participation in Fenton chemistry generates highly reactive hydroxyl radicals. Recent results have revealed a critical role for iron efflux transporters in protecting bacteria from iron intoxication...
July 19, 2017: Metallomics: Integrated Biometal Science
https://www.readbyqxmd.com/read/28593794/cthtra-the-lynchpin-of-the-chlamydial-surface-and-a-promising-therapeutic-target
#19
James W Marsh, Vanissa A Ong, William B Lott, Peter Timms, Joel DA Tyndall, Wilhelmina M Huston
Chlamydia trachomatis is the most prevalent sexually transmitted bacterial infection worldwide and the leading cause of preventable blindness. Reports have emerged of treatment failure, suggesting a need to develop new antibiotics to battle Chlamydia infection. One possible candidate for a new treatment is the protease inhibitor JO146, which is an effective anti-Chlamydia agent that targets the CtHtrA protein. CtHtrA is a lynchpin on the chlamydial cell surface due to its essential and multifunctional roles in the bacteria's stress response, replicative phase of development, virulence and outer-membrane protein assembly...
June 8, 2017: Future Microbiology
https://www.readbyqxmd.com/read/28592862/identification-of-unique-cardiolipin-and-monolysocardiolipin-species-in-acinetobacter-baumannii
#20
Patrizia Lopalco, Julia Stahl, Cosimo Annese, Beate Averhoff, Angela Corcelli
Acidic glycerophospholipids play an important role in determining the resistance of Gram-negative bacteria to stress conditions and antibiotics. Acinetobacter baumannii, an opportunistic human pathogen which is responsible for an increasing number of nosocomial infections, exhibits broad antibiotic resistances. Here lipids of A. baumannii have been analyzed by combined MALDI-TOF/MS and TLC analyses; in addition GC-MS analyses of fatty acid methyl esters released by methanolysis of membrane phospholipids have been performed...
June 7, 2017: Scientific Reports
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