Mechanisms of Bacillus subtilis spore resistance to and killing by aqueous ozone.
OBJECTIVE
To determine the mechanisms of Bacillus subtilis spore killing by and resistance to aqueous ozone.


RESULTS
Killing of B. subtilis spores by aqueous ozone was not due to damage to the spore's DNA, as wild-type spores were not mutagenized by ozone and wild-type and recA spores exhibited very similar ozone sensitivity. Spores (termed alpha-beta-) lacking the two major DNA protective alpha/beta-type small, acid-soluble spore proteins exhibited decreased ozone resistance but were also not mutagenized by ozone, and alpha-beta- and alpha-beta-recA spores exhibited identical ozone sensitivity. Killing of spores by ozone was greatly increased if spores were chemically decoated or carried a mutation in a gene encoding a protein essential for assembly of the spore coat. Ozone killing did not cause release of the spore core's large depot of dipicolinic acid (DPA), but these killed spores released all of their DPA after a subsequent normally sublethal heat treatment and also released DPA much more readily when germinated in dodecylamine than did untreated spores. However, ozone-killed spores did not germinate with either nutrients or Ca(2+)-DPA and could not be recovered by lysozyme treatment.


CONCLUSIONS
Ozone does not kill spores by DNA damage, and the major factor in spore resistance to this agent appears to be the spore coat. Spore killing by ozone seems to render the spores defective in germination, perhaps because of damage to the spore's inner membrane.


CONCLUSIONS
These results provide information on the mechanisms of spore killing by and resistance to ozone.
Young
S B
SB
Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, CT 06032-3305, USA.
Setlow
P
P
D000588:Amines / Q000378:metabolism; D001412:Bacillus subtilis / Q000187:drug effects* / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D004269:DNA, Bacterial / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000502:physiology; D004791:Enzyme Inhibitors / Q000378:metabolism; D016296:Mutagenesis / Q000187:drug effects; D010083:Oxidants, Photochemical / Q000494:pharmacology*; D010126:Ozone / Q000494:pharmacology*; D010848:Picolinic Acids / Q000378:metabolism; D013171:Spores, Bacterial / Q000187:drug effects; D013501:Surface-Active Agents / Q000378:metabolism
D000588:Amines; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D010083:Oxidants, Photochemical; D010848:Picolinic Acids; D013501:Surface-Active Agents; C030069:spore-specific proteins, Bacillus; D010126:Ozone; C004860:dipicolinic acid; C003935:dodecylamine