Physiological and transcriptional responses and cross protection of Lactobacillus plantarum ZDY2013 under acid stress

Abstract

Acid tolerance responses (ATR) in Lactobacillus plantarum ZDY2013 were investigated at physiological and molecular levels. A comparison of composition of cell membrane fatty acids (CMFA) between acid-challenged and unchallenged cells showed that acid adaptation evoked a significantly higher percentage of saturated fatty acids and cyclopropane fatty acids in acid-challenged than in unchallenged cells. In addition, reverse transcription-quantitative PCR analysis in acid-adapted cells at different pH values (ranging from 3.0 to 4.0) indicated that several genes were differently regulated, including those related to proton pumps, amino acid metabolism, sugar metabolism, and class I and class III stress response pathways. Expression of genes involved in fatty acid synthesis and production of alkali was significantly upregulated. Upon exposure to pH 4.5 for 2 h, a higher survival rate (higher viable cell count) of Lactobacillus plantarum ZDY2013 was achieved following an additional challenge to 40 mM hydrogen peroxide for 60 min, but no difference in survival rate of cells was found with further challenge to heat, ethanol, or salt. Therefore, we concluded that the physiological and metabolic changes of acid-treated cells of Lactobacillus plantarum ZDY2013 help the cells resist damage caused by acid, and further initiated global response signals to bring the whole cell into a state of defense to other stress factors, especially hydrogen peroxide.

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“…Moreover, compositions of LAB in milk are different to studies on LAB found in fermented milk products which are predominantly lactobacilli [6,21,35]. This is because fatty acids compositions of the membrane and related genes could promote survival of lactobacilli in acid environment and therefore associated with milk that has undergone fermentation [22].…”

Enhanced Exopolysaccharide Production by Lactobacillus rhamnosus in Co-Culture with Saccharomyces cerevisiae

“…Cyclopropanation increases membrane stability when facing stress conditions affecting the membrane, such as acid stress [51]. The same strategy to resist stress conditions was described for Lactobacillus plantarum at pH 3 [52].…”

“…Similarly, a set of genes involved in tolerance to one or more environmental stresses was induced during the acid stress responses (class I and III stress response pathways) for Lb. plantarum [52]. The involvement of the heat-shock proteins with the Clp proteins, pertinent to acid-mediated stress, is a feature across Lactobacillus species [43].…”

Screening and evaluation of Monascus purpureusFJMR24 for enhancing the raw material utilization rate in rice wine brewing

“…2(D) and (F)) would contribute to the thermotolerance of FJMR24. In addition, the high level of stress proteins induced by one stress event could improve the adaptability of a strain to other stresses, 40 indicating that an adaptive response may initiate cross‐protective mechanisms 41 . According to these concepts, the thermo‐resistance of FJMR24 would help improve its adaptability to high alcohol and acid, and vice versa .…”