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Killing the spores of Bacillus species by molecular iodine
Author(s) -
Li Q.,
Korza G.,
Setlow P.
Publication year - 2017
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.13310
Subject(s) - spore , bacillus subtilis , bacillus anthracis , germination , microbiology and biotechnology , bacillus thuringiensis , biology , lysis , endospore , bacteria , botany , genetics
Aims To determine the responses of spores of Bacillus subtilis and Bacillus anthracis surrogate Bacillus thuringiensis Al Hakam to I 2 treatment. Methods and Results Spores of B. subtilis and B. thuringiensis killed by aqueous 30°C‐I 2 could germinate, and their inner membrane (IM) was intact. Spore coats were important in I 2 resistance, DNA‐protective proteins were not important, and survivors of I 2 treatment were not mutagenized. Viabilities of I 2 ‐treated, 90–98% killed spores were much lower on high‐salinity media, and the treated spores were more heat sensitive than the untreated spores. Germinated I 2 ‐killed spores were dead as determined by staining with nucleic acid dyes, and many appeared to have been lysed. Conclusions Aqueous I 2 appeared to kill B. subtilis and B. thuringiensis spores such that spores lyse soon after they germinate, and not by causing DNA damage or rupture of spores’ IM. I 2 treatment also generated many damaged spores that could only be recovered under nonstressful conditions. Significance and Impact of the Study This work shows that spores of the model organism B. subtilis , and B. thuringiensis , a surrogate for B. anthracis spores, exhibit similar mechanisms of resistance to and killing by I 2 . Generation by I 2 treatment of conditionally dead spores indicates that appropriate media are essential to efficiently enumerate viable I 2 ‐treated spores.