otsA single gene knock-out in Escherichia coli increases cell sensitivity to outer membrane destabilization by SDS and EDTA treatment

Trehalose is a disaccharide consisting of two glucose molecules and is produced by various organisms, including Escherichia coli via the otsBA operon. It is
proposed to be a stress protectant for cells under abiotic stress by stabilizing proteins and membranes. Here, we aim to elucidate if E. coli that are unable to synthesize trehalose due to an otsA gene deletion have increased susceptibility to abiotic stress that destabilizes the outer membrane by assessing cell viability. The surviving cell percentage of wild type MG1655 cells and mutant JW5312-3 cells lacking otsA were assessed after sodium dodecyl sulfate (SDS) and increasing concentrations of ethylenediaminetetraacetic acid (EDTA) treatment in culture media. Growth curve analysis and a low temperature viability assay as
abiotic stress control were also performed. JW5312-3 cells were more susceptible at a lower EDTA concentration and to low temperature stress than MG1655, both indicated by lower surviving cell percentages. However, JW5312-3 were found to have higher growth yield than MG1655, though they have the same growth rate. Our findings suggest that trehalose’ protective role in E. coli under abiotic stress may partly due to its outer membrane stabilizing effect and that deletion of one of the two genes in the otsBA operon only decreases cell viability and is not lethal to E. coli.