Affiliation:
1. Environmental Science Program, Food Research Center, University of Idaho, Moscow, Idaho, USA
2. University of Idaho and Washington State University School of Food Science, Food Research Center, Moscow, Idaho, USA
Abstract
ABSTRACT
Bacillus pumilus
SAFR-032, isolated at spacecraft assembly facilities of the National Aeronautics and Space Administration Jet Propulsion Laboratory, is difficult to kill by the sterilization method of choice, which uses liquid or vapor hydrogen peroxide. We identified two manganese catalases, YjqC and BPUM_1305, in spore protein extracts of several
B. pumilus
strains by using PAGE and mass spectrometric analyses. While the BPUM_1305 catalase was present in six of the
B. pumilus
strains tested, YjqC was not detected in ATCC 7061 and BG-B79. Furthermore, both catalases were localized in the spore coat layer along with laccase and superoxide dismutase. Although the initial catalase activity in ATCC 7061 spores was higher, it was less stable over time than the SAFR-032 enzyme. We propose that synergistic activity of YjqC and BPUM_1305, along with other coat oxidoreductases, contributes to the enhanced resistance of
B. pumilus
spores to hydrogen peroxide. We observed that the product of the catalase reaction, gaseous oxygen, forms expanding vesicles on the spore surface, affecting the mechanical integrity of the coat layer, resulting in aggregation of the spores. The accumulation of oxygen gas and aggregations may play a crucial role in limiting further exposure of
Bacilli
spore surfaces to hydrogen peroxide or other toxic chemicals when water is present.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
26 articles.
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