title: Comparative analysis of naturally occurring L-amino acid osmolytes and their D-isomers on protection of Escherichia coli against environmental stresses.
abstract: Adaptation to high salinity and low or high temperature is essential for bacteria to survive. Accumulation of exogenous osmolytes is one of the ways that helps bacteria to survive under such extracellular stress. We have analysed the capability of various L-amino acids and their D-isomers to act as osmolytes and thus enable Escherichia coli cells to survive under various stress conditions. E. coli cells were grown in the presence or absence of L- and D-proline, alanine, serine and lysine under salt, heat and cold stresses. Of the various amino acids tested, L-proline, closely followed by L-serine turned out to be highly protective against environmental stresses. L-proline provided excellent protection (95%) against salt stress, followed by cold (60%) and heat (40%) stresses. D-amino acids on the other hand, proved to be highly inhibitory under stress conditions. Thus L-amino acids were found to be growth protectants under stress while their D-isomers were inhibitory during stress as well as normal conditions.
authors.affiliation: Department of Biosciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110 025, India.
authors.forename: Hanief Md
authors.initials: HM
authors.lastname: Shahjee
authors.forename: Kakoli
authors.initials: K
authors.lastname: Banerjee
authors.forename: Faizan
authors.initials: F
authors.lastname: Ahmad
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000494:pharmacology*; D003080:Cold Temperature; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D006358:Hot Temperature; D012965:Sodium Chloride; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D012965:Sodium Chloride