Overproduction of exopolysaccharides by an Escherichia coli K-12 rpoS mutant in response to osmotic stress

The overinduction of the yjb operon and that of other genes involved in extracellular polysaccharide (EPS) production are shown to be an adaptive response to osmotic stress in an rpoS-deficient background and that these overinduced genes are of special value for an rpoS-deficient strain. The results have shown that alternative stress response strategies have played a role in the absence of RpoS or when its activity is reduced, allowing the cells to survive and proliferate even without its general stress protection.