The role of trehalose in the osmoadaptation of Escherichia coli NCIB 9484: interaction of trehalose, K+ and glutamate during osmoadaptation in continuous culture

Abstract

Natural abundance 13C nuclear magnetic resonance spectroscopy identified the disaccharide trehalose as the major organic osmolyte synthesized by Escherichia coli grown in continuous culture under nitrogen limitation in the presence of 0.5 M-NaCl. Trehalose accumulation was dependent on both the growth phase of the culture and the osmolality of the growth medium, but independent of the solute used to increase the osmolality as long as the solute was non-penetrant. The penetrant solute glycerol did not induce trehalose synthesis indicating that the loss of cell turgor rather than increasing medium osmolality per se was the mechanism stimulating trehalose synthesis. Under conditions of either carbon or nitrogen limitation osmoadaptation was distinctly biphasic. The initial response consisted of a rapid (within 30 min) accumulation of K+ and a concurrent synthesis of the amino acid glutamate; trehalose synthesis occurred during the second slower phase of osmoadaption. Chloramphenicol severely inhibited trehalose accumulation indicating that the enzyme(s) involved in trehalose synthesis were inducible.