Mutant strains of Clostridium botulinum ATCC 3502 were generated using the ClosTron in four genes (CBO1789, CBO1790, CBO3048, CBO3145) identified as encoding α/β-type SASP homologues. The spores of mutant strains in which CBO1789 or CBO1790 was inactivated demonstrated a significant increase in sensitivity to the damaging agent nitrous acid (P<0.01), a phenotype that was partially restored to wild-type in complementation studies. In contrast to nitrous acid, the spores of the CBO1789 and CBO1790 mutants showed no change in their resistance to formaldehyde and hydrogen peroxide (P>0.05), two other chemicals commonly used as components of disinfection regimes. These data indicate that the SASPs CBO1789 or CBO1790 play a significant role in resistance to nitrous acid, but not in resistance to formaldehyde or hydrogen peroxide.
Keywords: Bacterial spores; Chemical resistance; ClosTron; Clostridium species; Food poisoning.
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