Comparative Analysis of TA102 and WP2 uvrA(pKM101) Strains in Detecting Nitrosamine Mutagens in the Enhanced Ames Test

Abstract

The Ames test is a fundamental assay for evaluating chemical mutagenicity, particularly for nitrosamines, which are widespread environmental and pharmaceutical contaminants. To improve sensitivity, regulatory agencies have endorsed the enhanced Ames test (EAT), which incorporates five tester strains, a 30-min pre-incubation step, and metabolic activation using both rat and hamster liver S9 fractions. While Salmonella typhimurium TA102 is known for its sensitivity to oxidative mutagens, its performance under EAT conditions has not been fully characterized. This study evaluated the mutagenic response of TA102 using two nitrosamine positive controls: N-nitrosodimethylamine (NDMA) and 1-cyclopentyl-4-nitrosopiperazine (CPNP). E. coli WP2 uvrA(pKM101) showed consistent mutagenic responses to both NDMA and CPNP, consistent with existing EAT data. TA102 demonstrated a robust response to NDMA but not to CPNP, suggesting limited sensitivity to certain nitrosamines. These findings support the continued use of WP2 uvrA(pKM101) in EAT protocols and highlight the limited utility of TA102 for comprehensive nitrosamine mutagenicity assessment.