Extreme Spore UV Resistance of Bacillus pumilus Isolates Obtained from an Ultraclean Spacecraft Assembly Facility
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Recent environmental microbial sampling of the ultraclean Spacecraft Assembly Facility at NASA Jet Propulsion Laboratory (JPL-SAF) identified spores of Bacillus pumilus as major culturable bacterial contaminants found on and around spacecraft. As part of an effort to assess the efficacy of various spacecraft sterilants, purified spores of 10 JPL-SAF B. pumilus isolates were subjected to 254-nm UV and their UV resistance was compared to spores of standard B. subtilis biodosimetry strains. Spores of six of the 10 JPL-SAF isolates were significantly more resistant to UV than the B. subtilis biodosimetry strain, and one of the JPL-SAF isolates, B. pumilus SAFR-032, exhibited the highest degree of spore UV resistance observed by any Bacillus spp. encountered to date.
KeywordsBacillus Pumilus Type Strain ATCC Planetary Protection H2O2 Resistance Liquid H2O2
The authors thank Michael Kempf for sharing data prior to publication. This work was supported by contract No. 1238194 from NASA-JPL and grant NCC2-1342 from the NASA Exobiology program to W.L.N., and by a University of Arizona-NASA Space Grant to J.S. A portion of this work (K.V.) was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.
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