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Acid Stress (acid + stress)
Selected AbstractsBile salts and cholesterol induce changes in the lipid cell membrane of Lactobacillus reuteriJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2003M.P. Taranto Abstract Aims: The objective of this study was to evaluate the effect of bile salts and cholesterol in the lipid profile of Lactobacillus reuteri CRL 1098 and to determine the relationship existing between these changes: the in vitro removal of cholesterol and the tolerance of the cells to acid and cold stress. Methods and Results:Lactobacillus reuteri CRL 1098 was grown in the following media: MRS (deMan Rogosa Sharpe; MC, control medium), MB (MC with bile salts), MCH (MC with sterile cholesterol) and MBCH (MC with bile salts and cholesterol). Fatty acids were determined by analytical gas,liquid chromatography, and phospholipids and glycolipids by colorimetric techniques. The cells from different culture media were subjected to cold and acid stress. The MB cultures displayed a decrease in phospholipids and a low ratio of saturated : unsaturated fatty acids. The presence of the unusual C18 : 0,10-OH and C18 : 0,10-oxo fatty acids was the prominent characteristic of the bile salts growing cells. The relative increase in glycolipids and the changes in the fatty acids profiles of the MB cells would be responsible for the cholesterol remotion. The changes induced by bile salts in the lipid profile did not improve the tolerance of L. reuteri CRL 1098 to freezing and acid stress. Conclusions: The changes in lipid profiles reported in this study would play a key role in the response of Lactobacilli to environmental stress. Significance and Impact of the Study: This work provides useful information about the effect of bile salts on the cell membrane of L. reuteri, a probiotic enterolactobacillus. The steady-state response of the cells subjected to bile stress seems to be the appropriate model for evaluating the bacterial behaviour in detergent-containing gastrointestinal tracts, where the bile salts stress would presumably be continuous. [source] Effects of butyric acid stress on anaerobic sludge for hydrogen production from kitchen wastesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2010Mingxing Zhao Abstract BACKGROUND: Anaerobic digestion is an alternative technology to achieve the dual benefits of hydrogen production and waste stabilization from kitchen wastes. In this work, the butyric acid stress on anaerobic sludge was investigated in order to improve the tolerance of sludge against organic acids, and to enhance hydrogen accumulation. RESULTS: The tolerance of butyric acid in anaerobic sludge increased with the stress concentration, however, it decreased at concentrations greater than of 4.0 g L,1. The maximum hydrogen yield reached 63.72 mL g,1 VS at 4.0 g L,1 stress, representing an increase of 114% compared with the control group. The concentration of volatile solids (VS) of the sludge and SCOD increased steadily with time up to 20 h. At 4.0 g L,1 butyric acid stress, the maximum activity of ,-glucosidase, BAA-hydrolysing protease and dehydrogenase enzyme were 14912.1 µmol PNP g,1 TS h,1, 134.14 µmol NH4 -N g,1 TS h,1 and 7316.42 µg TF g,1 TS h,1, which were 2.78, 1.90 and 2.01 times that of the control, respectively. CONCLUSIONS: The feasibility of butyric acid stress on anaerobic sludge to increase hydrogen production from kitchen wastes was demonstrated. Remarkably, 4.0 g L,1 butyric acid stress was found to be favorable for improving the tolerance of butyric acid in sludge as well as hydrogen yield in the experiment. Copyright © 2010 Society of Chemical Industry [source] Toxic effect of environmental acid-stress on the sperm of a hill-stream fish Devario aequipinnatus: A scanning electron microscopic evaluationMICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2009Sudip Dey Abstract Environmental stress due to acidic pH of water was found to be one of the major factors leading to toxic effects on the sperm of a hill-stream fish Devario aequipinnatus of Meghalaya, India. The Scanning Electron Microscopy of the transverse section of testes of the fish collected from its natural habitat with acidic pH (5.6,6.0) showed that the sperms were clumped together and their tails were either absent or were of extremely small length. The acrosome and midpiece were also not well differentiated. When the fingerlings from the natural habitat were reared to maturity in aquarium with water from natural habitat after changing the pH to alkaline range (8.0,8.2), the clumping of the sperm was not observed. The sperm tail was found to be well-developed along with well-differentiated acrosome and midpiece. Since the only change in the water quality parameters of the experimental aquarium as compared to those of the natural habitat was the pH, it is evident that the abnormal features of the sperm observed in fish from natural habitat is mainly because of environmental acid stress. Microsc. Res. Tech., 2009. © 2008 Wiley-Liss, Inc. [source] A multifaceted role for polyamines in bacterial pathogensMOLECULAR MICROBIOLOGY, Issue 1 2008Pratik Shah Summary Polyamines are polycationic molecules with a hydrocarbon backbone and multiple amino groups. Descriptions of the physiological roles of polyamines have often been limited to their interaction with negatively charged nucleic acids. Of late, reports linking polyamines to microbial carcinogenesis, biofilm formation, escape from phagolysosomes, bacteriocin production, toxin activity and protection from oxidative and acid stress have been published, providing insights about their other important but lesser known functions. This review focuses on recently discovered novel functions of polyamines in microorganisms, with an emphasis on bacterial pathogens of humans. [source] The Shigella dysenteriae serotype 1 proteome, profiled in the host intestinal environment, reveals major metabolic modifications and increased expression of invasive proteinsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 22 2009Rembert Pieper Abstract Shigella dysenteriae serotype 1 (SD1) causes the most severe form of epidemic bacillary dysentery. We present the first comprehensive proteome analysis of this pathogen, profiling proteins from bacteria cultured in vitro and bacterial isolates from the large bowel of infected gnotobiotic piglets (in vivo). Overall, 1061 distinct gene products were identified. Differential display analysis revealed that SD1 cells switched to an anaerobic energy metabolism in vivo. High in vivo abundances of amino acid decarboxylases (GadB and AdiA) which enhance pH homeostasis in the cytoplasm and protein disaggregation chaperones (HdeA, HdeB and ClpB) were indicative of a coordinated bacterial survival response to acid stress. Several type III secretion system effectors were increased in abundance in vivo, including OspF, IpaC and IpaD. These proteins are implicated in invasion of colonocytes and subversion of the host immune response in S. flexneri. These observations likely reflect an adaptive response of SD1 to the hostile host environment. Seven proteins, among them the type III secretion system effectors OspC2 and IpaB, were detected as antigens in Western blots using piglet antisera. The outer membrane protein OmpA, the heat shock protein HtpG and OspC2 represent novel SD1 subunit vaccine candidates and drug targets. [source] The effect of low pH on protein expression by the probiotic bacterium Lactobacillus reuteriPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 8 2008KiBeom Lee Dr. Abstract The ability of a lactic acid bacterium to survive passage through the gastrointestinal tract is a key point in its function as a probiotic. In this study, protein synthesis by the probiotic bacterium, Lactobacillus reuteri, was analyzed under transiently decreased pH conditions. L. reuteri cells grown to the midexponential growth phase at 37°C were exposed to transient (1,h) low-pH stresses from pH,6.8 to pH,5.0, 4.5, or 4.0. 2-DE allowed us to identify 40 common proteins that were consistently and significantly altered under all three low-pH conditions. PMF was used to identify these 40 proteins, and functional annotation allowed them to be distributed to six major classes: (i) transport and binding proteins; (ii) transcription,translation; (iii) nucleotide metabolism and amino acid biosynthesis; (iv) carbon energy metabolism; (v) pH homeostasis and stress; and (vi) unassigned. These findings provide new insight into the inducible mechanisms underlying the capacity of gastrointestinal L. reuteri to tolerate acid stress. [source] The effect of vitamin C on stress withstanding capability in the juvenile soft-shelled turtle (Pelodiscus sinensis)AQUACULTURE NUTRITION, Issue 3 2005XIAN-QING ZHOU Abstract The study was conducted to determine the effect of dietary supplementation of vitamin C on anti-acid stress ability in juvenile soft-shelled turtle. The soft-shelled turtles were fed vitamin C supplemented diets at levels of 0, 250, 500, 2500, 5000 and 10 000 mg kg,1 for 4 weeks. The results showed that the phagocytic rate of blood cell in the group fed vitamin C deficient diets, the serum bacteriolytic activity in the two groups fed vitamin C supplemented diet at 0 and 250 mg kg,1 and the serum bactericidal activity in all groups after acid stress significantly decreased compared with those of before stress (P < 0.1). The phagocytic rate of blood cells in the two groups fed vitamin C supplemented diet at 2500 and 5000 mg kg,1 were significantly higher than those of the four groups fed at 0, 250, 500 and 10 000 mg kg,1 (P < 0.01). The serum bacteriolytic activity in the groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg,1 were significantly higher than that of the group fed vitamin C deficient diets (P < 0.05), and the two groups fed vitamin C at 2500 and 5000 mg kg,1 were significantly higher than those of the groups fed at 250 and 10 000 mg kg,1 (P < 0.05). The serum bactericidal activities in the four groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg,1 were significantly higher than those of the two groups fed at 0 and 250 mg kg,1 diet (P < 0.01), and the two groups fed vitamin C at 2500 and 5000 mg kg,1 were significantly higher than those of the two groups fed at 500 and 10 000 mg kg,1 (P < 0.1). These results suggest that supplementation of vitamin C higher than 250 mg kg,1 is necessary to reduce the adverse effects of acid stress. [source] | |||||||||||||