Role of L-Glutamate in the Tolerance of Osmotic Stress by <i>Escherichia coli</i>

Abstract

Studies on the cellular response to conditions of physical or chemical stress have played a very significant role in diverse areas of biology. The present investigation aims at determining concentrations of NaCl that are stressful for environmental and clinical strains of Escherichia coli and to investigate the effect of L-glutamate to counteract such stressful conditions. It was observed that growth of environmental, clinical and reference strains could be stressed by a NaCl concentration of 0.9 M. Growth decreased under conditions of stress as opposed to that without added NaCl. Clinical isolates showed much higher resistance than environmental strains to osmotic stress. Glutamate had a significant effect in overcoming osmotic stress under laboratory conditions. This was indicated by increased growth in the presence of glutamate (15 mM) compared to that occurred at 0.9 M NaCl without added glutamate. Distinct protein bands were produced under stressful conditions, which indicate that these proteins might be stress proteins that aid the isolates to counteract osmotic stress.

Keywords: Osmotic stress; L-Glutamate; Escherichia coli

DOI: http://dx.doi.org/10.3329/bjm.v25i1.4865

Bangladesh J Microbiol, Volume 25, Number 1, June 2008, pp 79-81