UNLABELLED

This study investigated the acid tolerance responses of LM1001 at physiological and molecular levels. Upon exposure to low pH, LM1001 demonstrated increased ATPase activity and ammonia consumption, which contributed to a higher intracellular pH. Comparative analysis of cell membrane fatty acids revealed that acid-stressed cells had a significantly higher proportion of unsaturated fatty acids than those of unstressed cells. There was differential upregulation of several genes, notably those involved in alkali production ( and ) and in class I and class III stress responses ( and ). Following 2-h exposure to pH 2.5, LM1001 not only exhibited enhanced survival but also showed increased auto-aggregation and improved mucin adhesion capability, albeit with a reduction in hydrophobicity. These findings indicate that acid stress induces adaptive physiological and metabolic changes in LM1001, enhancing its acid resistance and adherence properties.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10068-024-01582-4.