Involvement of the mannose phosphotransferase system of Lactobacillus plantarum WCFS1 in peroxide stress tolerance.

A Lactobacillus plantarum strain with a deletion in the gene rpoN, encoding the alternative sigma factor 54 (sigma(54)), displayed a 100-fold-higher sensitivity to peroxide than its parental strain. This feature could be due to sigma(54)-dependent regulation of genes involved in the peroxide stress response. However, transcriptome analyses of the wild type and the mutant strain during peroxide exposure did not support such a role for sigma(54). Subsequent experiments revealed that the impaired expression of the mannose phosphotransferase system (PTS) operon in the rpoN mutant caused the observed increased peroxide sensitivity.