Open AccessAccumulation of glutamate by osmotically stressed Escherichia coli is dependent on pH
Author(s) -
Tokuli Ogahara,
Masahiro Ohno,
Miki Takayama,
Kazuei Igarashi,
Hiroshi Kobayashi
Publication year - 1995
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.177.20.5987-5990.1995
Subject(s) - osmotic concentration , osmotic shock , osmolyte , potassium , biology , sodium , escherichia coli , glutamate receptor , biochemistry , sodium glutamate , sucrose , biophysics , chemistry , raw material , ecology , receptor , organic chemistry , gene
In the present study, we measured the accumulation of glutamate after hyperosmotic shock in Escherichia coli growing in synthetic medium. The accumulation was high in the medium containing sucrose at a pH above 8 and decreased with decreases in the medium pH. The same results were obtained when the hyperosmotic shock was carried out with sodium chloride. The internal level of potassium ions in cells growing at a high pH was higher than that in cells growing in a neutral medium. A mutant deficient in transport systems for potassium ions accumulated glutamate upon hyperosmotic stress at a high pH without a significant increase in the internal level of potassium ions. When the medium osmolarity was moderate at a pH below 8, E. coli accumulated gamma-aminobutyrate and the accumulation of glutamate was low. These data suggest that E. coli uses different osmolytes for hyperosmotic adaptation at different environmental pHs.