Changes in Protein Synthesis and Morphology during Acid Adaptation of Propionibacterium freudenreichii

Abstract

Survival of bacteria in changing environments depends on their ability to adapt to abiotic stresses. Microorganisms used in food technology face acid stress during fermentation processes. Similarly, probiotic bacteria have to survive acid stress imposed within the stomach in order to reach the intestine and play a beneficial role. Propionibacteria are used both as cheese starters and as probiotics in human alimentation. Adaptation to low pH thus constitutes a limit to their efficacy. Acid stress adaptation in the probiotic SI41 strain of Propionibacterium freudenreichii was therefore investigated. The acid tolerance response (ATR) was evidenced in a chemically defined medium. Transient exposure to pH 5 afforded protection toward acid challenge at pH 2. Protein neosynthesis was shown to be required for optimal ATR, since chloramphenicol reduced the acquired acid tolerance. Important changes in genetic expression were observed with two-dimensional electrophoresis during adaptation. Among the up-regulated polypeptides, a biotin carboxyl carrier protein and enzymes involved in DNA synthesis and repair were identified during the early stress response, while the universal chaperonins GroEL and GroES corresponded to a later response. The beneficial effect of ATR was evident at both the physiological and morphological levels. This study constitutes a first step toward understanding the very efficient ATR described in P. freudenreichii.

Induction of Manganese-Containing Superoxide Dismutase Is Required for Acid Tolerance inVibrio vulnificus

“…Acid also could affect all the cell components from the membrane to the cytosol, and the proteins therein could be partly unfolded but still work to generate reactive oxygen species including superoxide under aerobic conditions. Interestingly, there have been reports of increased expression of both DnaK and GroEL/ES classes of chaperones in response to growth at low pH (15,36). By the same token, the experimental results shown in this work can also suggest that a lack of either MnSOD or FeSOD of V. vulnificus may result in intracellular buildup of superoxide, which causes cellular damage that renders the cell more sensitive to the acid stress.…”

CsrRS Regulates Group BStreptococcusVirulence Gene Expression in Response to Environmental pH: a New Perspective on Vaccine Development

“…1), consistent with a requirement for de novo protein synthesis for adaptation to an acidic environment (24). In addition, genes encoding transport and binding proteins were regulated at an acidic pH, with a total of 50 genes upregulated and only 2 downregulated (SAG1467 and SAG1813).…”

Effect of Environmental Stresses on S-Layer Production in Lactobacillus acidophilus ATCC 4356

“…To study the effect of heat and pH stresses on S-layer production and slpA gene expression, the Lactobacillus acidophilus ATCC 4356 was cultivated in MRS broth (Merck) for heat stress (30, 45, 50 and 55 o C) (Kim et al, 2001); for pH stress, MRS broth was adjusted to pH 3-7 (adjusted with HCl and NaOH) (Jan et al, 2001;Lorca et al, 1998). The pH and temperature of the control culture (MRS broth) were 6.5 and 37 o C, respectively, according to manufacturer's recommendation and as described previously (Boot et al, 1993;Silva et al, 2005;Smit et al, 2001).…”