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Ecology and Thermal Inactivation of Microbes in and on Interplanetary Space Vehicle ComponentsSpores of Bacillus subtilis var. niger were heat treated in aqueous suspension at 90 C, and observed for morphological changes and loss of viability. The 5 logs reduction that occurred in broth at 90 min required 210 min in buffered water. Five characteristic changes observed after spores were exposed 120 min at 90 C in buffered water were: (1) 90% loss of spore viability, (2) 5% stainability, (3) 76% increase in spore size (as observed by scanning electron microscopy), (4) 21% of spore areas remaining refractile, and (5) an increase of 77% in packed cell volume (PCV). Stainability and PCV changes were recognized only after secondary exposure in broth. Extended heat exposure (3 h at 90 C) resulted in 99% loss of spore viability and 99% loss of stainability. After 4 hours of heat exposure, 90% of the cells disintegrated. These results suggest that early germinal changes occurr concurrently with the early changes in the heat susceptibility of dormant spores.
Document ID
19760010694
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Reyes, A. L. (Food and Drug Administration Cincinnati, OH, United States)
Campbell, J. E. (Food and Drug Administration Cincinnati, OH, United States)
Date Acquired
September 3, 2013
Publication Date
September 1, 1975
Subject Category
Life Sciences (General)
Report/Patent Number
QPR-41
NASA-CR-146401
Accession Number
76N17782
Funding Number(s)
CONTRACT_GRANT: NASA ORDER W-13411
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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