Acid- and multistress-resistant mutants of Lactococcus lactis : identification of intracellular stress signals.

摘要: Lactococcus lactis growth is accompanied by lactic acid production, which results in acidification of the medium and arrest cell multiplication. Despite limitation at low pH, there evidence that lactococci do have inducible responses to an pH. In order characterize genes involved tolerance responses, we selected acid-resistant insertional mutants L. strain MG1363. Twenty-one independent characterized were affected 18 different loci, some are implicated transport systems or base metabolism. None these was identified previously as lactococcal tolerance. The various phenotypes obtained stress selection allowed us define four classes mutants, two comprise multistress-resistant strains. Our reveal has several means protecting itself against least one multiple resistance. particular, intracellular phosphate guanine nucleotide pools, notably (p)ppGpp, likely act signals determine level response induction. provide a link between physiological state establish role for stringent regulation.