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Effects of steam autoclave treatment on Geobacillus stearothermophilus spores
Author(s) -
HuescaEspitia L.C.,
Suvira M.,
Rosenbeck K.,
Korza G.,
Setlow B.,
Li W.,
Wang S.,
Li Y.q.,
Setlow P.
Publication year - 2016
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.13257
Subject(s) - spore , autoclave , microbiology and biotechnology , dipicolinic acid , sterilization (economics) , germination , biology , geobacillus stearothermophilus , endospore , spore germination , nucleic acid , food science , enzyme , biochemistry , chemistry , botany , thermophile , organic chemistry , monetary economics , economics , foreign exchange market , foreign exchange
Aims To determine the mechanism of autoclave killing of Geobacillus stearothermophilus spores used in biological indicators ( BI s) for steam autoclave sterilization, and rates of loss of spore viability and a spore enzyme used in BI s. Methods and Results Spore viability, dipicolinic acid (DPA) release, nucleic acid staining, α‐glucosidase activity, protein structure and mutagenesis were measured during autoclaving of G. stearothermophilus spores. Loss of DPA and increases in spore core nucleic acid staining were slower than loss of spore viability. Spore core α‐glucosidase was also lost more slowly than spore viability, although soluble α‐glucosidase in spore preparations was lost more rapidly. However, spores exposed to an effective autoclave sterilization lost all viability and α‐glucosidase activity. Apparently killed autoclaved spores were not recovered by artificial germination in supportive media, much spore protein was denatured during autoclaving, and partially killed autoclave‐treated spore preparations did not acquire mutations. Conclusions These results indicate that autoclave‐killed spores cannot be revived, spore killing by autoclaving is likely by protein damage, and spore core α‐glucosidase activity is lost more slowly than spore viability. Significance and Impact of the Study This work provides insight into the mechanism of autoclave killing of spores of an organism used in BI s, and that a spore enzyme in a BI is more stable to autoclaving than spore viability.