Metabolic impact and potential exploitation of the stress reactions in lactobacilli (original) (raw)
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Acid Stress-Mediated Metabolic Shift in Lactobacillus sanfranciscensis LSCE1
Applied and Environmental Microbiology, 2011
Updated information and services can be found at: These include: REFERENCES http://aem.asm.org/content/77/8/2656#ref-list-1 at: This article cites 54 articles, 16 of which can be accessed free CONTENT ALERTS more» articles cite this article), Receive: RSS Feeds, eTOCs, free email alerts (when new http://aem.asm.org/site/misc/reprints.xhtml Information about commercial reprint orders: http://journals.asm.org/site/subscriptions/ To subscribe to to another ASM Journal go to:
2005
The organic acid lactate is the predominant fermentation product of Lactobacillus plantarum. The undissociated form of this organic acid is a strong growth inhibitor for the organism. Different theories have been postulated to explain the inhibitory effects of lactic acid: (i) toxicity arising from the dissipation of the membrane potential, (ii) acidification of the cytosol, or (iii) intracellular anion accumulation. In general, organic acid stresses are complex to study, since their toxicity is highly dependent on their degree of dissociation and thus on the pH. In this study, transcription profiles of L. plantarum grown in steady-state cultures that varied in lactate/lactic acid concentration, pH, osmolarity and absolute and relative growth rate, were compared by microarray analysis. By doing so, the differential expression of multiple groups of genes could specifically be attributed to the different aspects of lactic acid stress. A highly coherent group of lactic acid-responsive, cell surface protein-encoding genes was identified, to which no function has previously been assigned. Moreover, a group of genes that showed increased expression in response to the combination of lactic acid and a lower growth rate is expected to be involved in the formation of the alternative fermentation end-products malate, acetate and ethanol. One of these pathways is the phosphoketolase bypass that is typical for bifidobacteria.
Physiological and Metabolic Responses of Functional Lactic Acid Bacteria to Stress Factors
2018
In our study, six functional lactic acid bacterium strains (able to produce bacteriocins, exopolysaccharides, or S-layer proteins) were subjected to different stress conditions in order to evaluate their capacity to adapt to harsh environments. They were cultivated at different temperatures, below and above their optimal growth temperatures. Moreover, they were grown in presence of bile salts or NaCl, or in acidic media. Total proteins, lactic acid production, enzymatic activities and synthesis of the metabolites of biotechnological interest were evaluated for all growth conditions. Over expression of some proteins was detected in the electrophoretic pattern of the total protein extracts from the stressed cultures compared to the control cultures. Enzymatic activities and lactic acid production were, in general, directly related with growth. The tested strains maintained their capacity to synthesize the assayed metabolites under almost all stress conditions. Bacteriocin production o...
The acid-stress response in Lactobacillus sanfranciscensis CB1
2001
Lactobacillus sanfranciscensis CB1, an important sourdough lactic acid bacterium, can withstand low pH after initial exposure to sublethal acidic conditions. The sensitivity to low pH varied according to the type of acid used. Treatment of Lb. sanfranciscensis CB1 with chloramphenicol during acid adaptation almost completely eliminated the protective effect, suggesting that induction of protein synthesis was required for the acid-tolerance response. Two constitutively acid-tolerant mutants, CB1-5R and CB1-7R, were isolated using natural selection techniques after sequential exposure to lactic acid (pH 32). Two-dimensional gel electrophoresis analysis of protein expression by non-adapted, acid-adapted and acid-tolerant mutant cells of Lb. sanfranciscensis showed changes in the levels of 63 proteins. While some of the modifications were common to the acid-adapted and acid-tolerant mutant cells, several differences, especially regarding the induced proteins, were determined. The two mutants showed a very similar level of protein expression. Antibodies were used to identify heat-shock proteins DnaJ, DnaK,
Stress responses in lactic acid bacteria
Antonie van Leeuwenhoek, 2002
Lactic acid bacteria (LAB) constitute a heterogeneous group of bacteria that are traditionally used to produce fermented foods. The industrialization of food bio-transformations increased the economical importance of LAB, as they play a crucial role in the development of the organoleptique and hygienic quality of fermented products. Therefore, the reliability of starter strains in terms of quality and functional properties (important for the development of aroma and texture), but also in terms of growth performance and robustness has become essential. These strains should resist to adverse conditions encountered in industrial processes, for example during starter handling and storage (freeze-drying, freezing or spray-drying). The development of new applications such as life vaccines and probiotic foods reinforces the need for robust LAB since they may have to survive in the digestive tract, resist the intestinal flora, maybe colonize the digestive or uro-genital mucosa and express s...
Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology, 2002
Lactic acid bacteria are widely used as starter organisms in food fermentations. The development of such cultures as organisms fulfilling all metabolic, technical and handling requirements is the result of a multidisciplinary approach, i.e. to analyse, follow and direct the microbial ecology in food fermentations by molecular biology tools, gene cloning, biochemical and physiological analyses, pilot trials and modelling of behaviour and metabolism. The possibilities and restrictions of such an approach is given for cereal fermentations, namely sourdoughs. In this environment highly adapted lactobacilli are predominant, sharing the environment with yeasts present in traditional preparations. The competitiveness of these lactobacilli and their contribution to flavour, machineability and prebiosis of doughs and bread relies on their maltose and amino acid metabolism, use of electron acceptors and EPS formation. Their reactions on environmental stresses can be used to embed these recalcitrant organisms into starter culture preparations. Beyond the cereal environment the described strategy can be generally applied to understand ecosystems in food fermentations and finally control them.
The Lactic Acid Stress Response of Lactococcus lactis subsp. lactis
Current Microbiology, 1996
The lactic acid tolerance response (LATR) of the lactic acid bacterium Lactococcus lactis subsp. lactis has been studied. A dramatic increase in survival to a severe acid stress (pH 3.9) was obtained by preexposing the cells for 30 min to a mildly acid shock at pH 5.5. Whole-cell protein extract analysis revealed that during the acid tolerance response 33 polypeptides are induced over the level of naive cells. Among these are the major heat shock proteins DnaK and GroEL. In conjunction with a previous report , the results establish that L. lactis can adapt to lactic acid exposure in two different ways: a logarithmic phase LATR, which may be activated by protons, and a stationary-phase LATR, which needs no activation by protons. Both systems are independent of de novo protein synthesis. glass tubes containing 10 ml of M17 medium pH 7.4 [22] supplemented with 0.1% glucose.
Bioprocess and Biosystems Engineering, 2011
In this study, Lactobacillus rhamnosus, a renowned probiotic, was cultivated in fluctuating environment. Base gradients caused by a pH control in an industrial process and temperature gradients caused by uneven heating were simulated with a scale-down method. A pH gradient was created in a plug flow reactor (PFR). Expression of pH stress-related genes (atpA, aldB, cfa, groEL, hrcA and pstS) were studied as a relative gene expression study using ldhD as a reference gene. Expression measurements were carried out with the TRAC method. The responses of groEL, hrcA and atpA genes to temperature and pH changes were observed. The expression of phosphate uptake system-related pstS gene was induced almost linearly in the chemostat cultivation experiments when the base gradient in the PFR was increased. Correlations between the results from gene expression studies and freeze stability or acid stress survival were studied. However, by measuring the expression of these genes, we were not able to predict eventual freeze stability or survival from the acid stress test.
Inducible Gene Expression in Lactobacillus reuteri LTH5531 during Type II Sourdough Fermentation
Applied and Environmental Microbiology, 2005
Lactobacillus reuteri LTH5531 is a dominant member of the microbiota of type II sourdough fermentations. To investigate the genetic background of the ecological performance of LTH5531, in vivo expression technology was used to identify promoters that show elevated levels of expression during growth of this organism in a type II sourdough fermentation. Thirty-eight sourdough-induced fusions were detected, and 29 genes could be identified on the basis of the available sequence information. Four genes encoded stress-related functions (e.g., acid and general stress response), reflecting the harsh conditions prevailing during sourdough fermentation. Further, eight genes were involved in acquisition and synthesis of amino acids and nucleotides, indicating their limited availability in sourdough. The remaining genes were either part of functionally unrelated pathways or encoded hypothetical proteins. The identification of a putative proteinase and a component of the arginine deiminase path...