Open AccessGlycine betaine transport in a halotolerant Chromatium species
Author(s) -
Welsh David T.,
Herbert Rodney A.
Publication year - 1995
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1995.tb07495.x
Subject(s) - betaine , halotolerance , glycine , chromatium , chemistry , botany , environmental chemistry , biology , ecology , biochemistry , salinity , photosynthesis , amino acid
The addition of 1 mM glycine betaine to the growth medium of Chromatium sp. NCIMB 8379 relieved growth inhibition caused by exposure to supra‐optimal Nad concentrations. Intracellular glycine betaine concentrations were dependent upon the NaCl concentration of the growth medium up to 3 M exogenous Nad. Kinetic data for the accumulation of [methyl‐ 14 C]‐glycine betaine demonstrated that Chromatium sp. NCIMB 8379 possesses a constitutively expressed active transport system for glycine betaine. The transport system was saturable with respect to glycine betaine concentration and exhibited typical Michaelis‐Menten type kinetics: K m = 24 μ M, V max = 306 nmol min −1 mg protein −1 at an external NaCl concentration of 1 M. The rate of glycine betaine transport decreased progressively with increasing growth medium NaCl concentration. This transport system may represent an adaptive response to growth in high osmolarity environments in this halotolerant isolate, allowing accumulation of glycine betaine from the external cell environment or recycling synthesised glycine betaine which has passively diffused from the cell.