Rj. Rowbury et al., Properties of an L-glutamate-induced acid tolerance response which involves the functioning of extracellular induction components, J APPL MICR, 86(2), 1999, pp. 325-330
Escheichia coli became more acid tolerant following incubation for 60 min i
n a medium containing L-glutamate at pH 7.0, 7.5 or 8.5. Several agents, in
cluding cAMP, NaCl, sucrose, SDS and DOG, prevented tolerance appearing if
present with L-glutamate. Lesions in cysB, hns, fur, himA and relA, which f
requently affect pH responses, failed to prevent L-glutamate-induced acid t
olerance but a lesion in L-glutamate decarboxylase abolished the response.
Induction of acid tolerance by L-glutamate was associated with the accumula
tion in the growth medium of a protein (or proteins) which was able to conv
ert pH 7.0-grown cultures to acid tolerance, and the original L-glutamate-i
nduced tolerance response was dependent on this component(s). Acid toleranc
e 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 a
nd 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 require
d.