Effect of (alpha)-Keto Acids Against H2O2- and NaN3-Induced Mutagenesis in Different Strains of Salmonella Typhimurium

The protective effects of a-keto acids on the mutagenicity of H2O2 and NaN3 was investigated in Salmonella typhimurium TA 98, TA 100, TA 102. H2O2 (340 µg/plate) was mutagenic to the strains TA 98 and TA 102 while NaN3 (1.5 µg/plate) wasmutagenic only to TA100. The extents of protective effect of pyruvate (220-440 µg/plate) and a-keto glutarate (335-600 µg/plate)against H2O2 were observed to be 37%- 65% in TA 98 and TA 102. a-keto acids were ineffective against NaN3 induced mutagenicityin TA 100. H2O2 (340 µg/plate), in the presence of NaN3 (1.5 µg/plate) and α-keto acids (330-500 µg/plate), was found to benonmutagenic to the strain TA102. This cross-adaptive response might have been due to the intactness of the DNA repair system inTA 102. The above combination of H2O2, NaN3 and a-keto acids were found to be cytotoxic in TA 98 and TA 100, possibly because these strains carry uvr B mutation causing defect in their DNA repair system.