Killing bacterial spores by organic hydroperoxides

Killing of wild-type spores of Bacillus subtilis by t-butyl hydroperoxide, cumene hydroperoxide and peracetic acid was not through DNA damage, as shown by the absence of mutations in the survivors and the identical sensitivity of spores of strains with or without a recA mutation. In contrast, B. subtilis spores (termed alpha(-)beta(-)) lacking the DNA protective alpha/beta-type small, acid-soluble spore proteins (SASP) were more sensitive to t-butyl hydroperoxide and cumene hydroperoxide, and their killing was in large part through DNA damage, as shown by the high frequency of mutations in the survivors and the greater sensitivity of alpha(-)beta(-) recA spores. Analysis of t-butyl hydroperoxide-treated spores showed that generation of DNA damage in alpha(-)beta(-) spores was more rapid than in wild-type spores; alpha/beta-type SASP also protected against DNA strand breakage in vitro caused by t-butyl hydroperoxide. alpha/beta-Type SASP appeared to play no role in protection of spores from killing by peracetic acid; wild-type and alpha(-)beta(-) spores exhibited identical peracetic acid sensitivity and their killing by this agent appeared to be not through DNA damage.