Anaerobic cultures of Salmonella typhimurium do not exhibit inducible proteolytic function of the recA gene and recBC function.

In a strict anaerobic environment, lack of expression of bacterial recBC function and recA regulatory functions for the SOS repair system is demonstrated by the use of the carcinogenesis-mutagenesis assay and Salmonella phage P22 mutants requiring these host functions for replication. Therefore, we suggest that error-prone repair (SOS repair) is confined to aerobic environments in facultative anaerobes.