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Properties of an L‐glutamate‐induced acid tolerance response which involves the functioning of extracellular induction components
Author(s) -
Rowbury R. J.,
Humphrey T. J.,
Goodson M.
Publication year - 1999
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.1999.00676.x
Subject(s) - library science , medicine , computer science
Escherichia coli became more acid tolerant following incubation for 60 min in a medium containing l ‐glutamate at pH 7·0, 7·5 or 8·5. Several agents, including cAMP, NaCl, sucrose, SDS and DOC, prevented tolerance appearing if present with l ‐glutamate. Lesions in cysB , hns , fur, himA and relA , which frequently affect pH responses, failed to prevent l ‐glutamate‐induced acid tolerance but a lesion in l ‐glutamate decarboxylase abolished the response. Induction of acid tolerance by l ‐glutamate was associated with the accumulation in the growth medium of a protein (or proteins) which was able to convert pH 7·0‐grown cultures to acid tolerance, and the original l ‐glutamate‐induced tolerance response was dependent on this component(s). Acid tolerance was also induced by l ‐aspartate at pH 7·0 and induction of such tolerance was dependent on an extracellular protein (or proteins). The l ‐glutamate and l ‐aspartate acid tolerance induction processes are further examples of a number of stress tolerance responses which differ from most inductions in that extracellular components, including extracellular sensors, are required.