Previous studies showed that a Bacillus subtilis strain deficient in mismatch 
repair (MMR; encoded by the mutSL operon) promoted the production of 
stationary-phase-induced mutations. However, overexpression of the mutSL operon 
did not completely suppress this process, suggesting that additional DNA repair 
mechanisms are involved in the generation of stationary-phase-associated mutants 
in this bacterium. In agreement with this hypothesis, the results presented in 
this work revealed that starved B. subtilis cells lacking a functional error 
prevention GO (8-oxo-G) system (composed of YtkD, MutM, and YfhQ) had a dramatic 
propensity to increase the number of stationary-phase-induced revertants. These 
results strongly suggest that the occurrence of mutations is exacerbated by 
reactive oxygen species in nondividing cells of B. subtilis having an inactive 
GO system. Interestingly, overexpression of the MMR system significantly 
diminished the accumulation of mutations in cells deficient in the GO repair 
system during stationary phase. These results suggest that the MMR system plays 
a general role in correcting base mispairing induced by oxidative stress during 
stationary phase. Thus, the absence or depression of both the MMR and GO systems 
contributes to the production of stationary-phase mutants in B. subtilis. In 
conclusion, our results support the idea that oxidative stress is a mechanism 
that generates genetic diversity in starved cells of B. subtilis, promoting 
stationary-phase-induced mutagenesis in this soil microorganism.