Lack of a significant role for the PerR regulator in Bacillus subtilis spore resistance

Bacillus subtilis cells lacking the PerR repressor which regulates transcri ption of genes encoding oxidative stress protective proteins grew at 30-50% the rate of wild-type cells, and perR cultures accumulated rapidly growing suppressor mutants lacking the catalase whose expression is regulated by P erR. However, perR spores which retained the perR regulated catalase were o btained on plates. These perR spores had levels of oxidative stress protect ive proteins from 7- to 50-fold higher than those in wild-type spores, but perR spore resistance to heat, hydrogen peroxide and t-butyl hydroperoxide was essentially identical to that of wild-type spores, indicating that elev ated levels of proteins that protect growing cells from oxidizing agents pl ay no role in dormant spore resistance to these compounds. However, germina ted perR spores were much more resistant to alkyl hydroperoxides than were wild-type spores. (C) 2000 Federation of European Microbiological Societies . Published by Elsevier Science B.V. All rights reserved.