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Thermal resistance of naturally occurring airborne bacterial sporesSimulation of a heat process used in the terminal dry-heat decontamination of the Viking spacecraft is reported. Naturally occurring airborne bacterial spores were collected on Teflon ribbons in selected spacecraft assembly areas and subsequently subjected to dry heat. Thermal inactivation experiments were conducted at 105, 111.7, 120, 125, 130, and 135 C with a moisture level of 1.2 mg of water per liter. Heat survivors were recovered at temperatures of 135 C when a 30-h heating cycle was employed. Survivors were recovered from all cycles studied and randomly selected for identification. The naturally occurring spore population was reduced an average of 2.2 to 4.4 log cycles from 105 to 135 C. Heating cycles of 5 and 15 h at temperature were compared with the standard 30-h cycle at 111.7, 120, and 125 C. No significant differences in inactivation (alpha = 0.05) were observed between 111.7 and 120 C. The 30-h cycle differs from the 5- and 15-h cycles at 125 C. Thus, the heating cycle can be reduced if a small fraction (about 0.001 to 0.0001) of very resistant spores can be tolerated.
Document ID
19790042134
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Puleo, J. R.
(California Institute of Technology, Jet Propulsion Laboratory, Planetary Quarantine Laboratory, Cape Canaveral Fla., United States)
Bergstrom, S. L.
(Jet Propulsion Lab. Cape Canaveral, FL, United States)
Peeler, J. T.
(Food and Drug Administration, Div. of Microbiology, Cincinnati Ohio, United States)
Oxborrow, G. S.
(Food and Drug Administration Minneapolis, Minn., United States)
Date Acquired
August 9, 2013
Publication Date
September 1, 1978
Publication Information
Publication: Applied and Environmental Microbiology
Volume: 36
Subject Category
Man/System Technology And Life Support
Accession Number
79A26147
Funding Number(s)
CONTRACT_GRANT: NAS7-100
Distribution Limits
Public
Copyright
Other

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