title: Mutagenicity and cytotoxicity of the carcinogen-mutagen aflatoxin B1 in Streptococcus pneumoniae (Pneumococcus) and Salmonella typhimurium: dependence on DNA repair functions.
abstract: Strains R6, R6x and R6uvr-1 of Streptococcus pneumoniae (Pneumococcus) are sensitive to the cytotoxic effects of the mutagen/carcinogen aflatoxin B1 (AFB1). R6uvr-1 is more prone to the cytotoxic effects of AFB1 than the repair-proficient parental strain, R6. The same differential susceptibility of strains R6, R6x and R6uvr-1 was observed when UV light replaced metabolically activated AFB1. All pneumococcal strains were immutable by AFB1. AFB1 mutagenesis in Salmonella typhimurium strains was dependent on a functional RecA gene product. The enhancing effects of delta uvrB and plasmid pKM101 were found to be additive. Data presented are consistent with the following: (i) AFB1 toxic effects are due mainly to DNA binding of AFB1; (ii) AFB1 mutagenesis is dependent on error-prone DNA repair; (iii) Pneumococcus lacks an active error-prone (SOS) DNA-repair system.
mesh_terms: D016604:Aflatoxin B1; D000348:Aflatoxins / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000502:physiology; D002273:Carcinogens; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D009153:Mutagens; D010957:Plasmids; D011938:Rec A Recombinases; D012485:Salmonella typhi / Q000187:drug effects*; D013296:Streptococcus pneumoniae / Q000187:drug effects*
chemical_list: D000348:Aflatoxins; D001426:Bacterial Proteins; D002273:Carcinogens; D004269:DNA, Bacterial; D009153:Mutagens; D016604:Aflatoxin B1; D011938:Rec A Recombinases