Expression of the σB-dependent general stress regulon confers multiple stress resistance in Bacillus subtilis

  • 1 July 1999
    • journal article
    • research article
    • Vol. 181  (13) , 3942-3948
Abstract
The alternative sigma factor sigma(B) of Bacillus subtilis is required for the induction of approximately 100 genes after the imposition of a whole range of stresses and energy limitation. In this study, we investigated the impact of a null mutation in sigB on the stress and starvation survival of B, subtilis. sigB mutants which failed to induce the regulon following stress displayed an at least 50- to 100-fold decrease in survival of severe heat (54 degrees C) or ethanol (9%) shock, salt (10%) stress, and acid (pH 4.3) stress, as well as freezing and desiccation, compared to the wild type. Preloading cells with sigma(B)-dependent general stress proteins prior to growth inhibiting stress conferred considerable protection against heat and salt. Exhaustion of glucose or phosphate induced the sigma(B) response, but surprisingly, sigma(B) did not seem to be required for starvation survival. Starved wild-type cells exhibited about 10-fold greater resistance to salt stress than exponentially growing cells. The data argue that the expression of sigma(B)-dependent genes provides nonsporulated B. subtilis cells with a nonspecific multiple stress resistance that may be relevant for stress survival in the natural ecosystem.