The comparative responses of Salmonella typhimurium TA1537 and TA97a to a range of reference mutagens and novel compounds.

Salmonella typhimurium TA97a was added to the set of indicator strains routinely used for the Ames test in this laboratory (TA1535, TA1537, TA1538, TA98 and TA100) for a trial period during which a total of approximately 40 reference mutagens and novel pharmaceutical compounds were examined. The conclusions from this trial were as follows: (i) there are agents mutagenic for TA1537 which are not detected by TA97a. (ii) except for agents requiring the R factor plasmid, TA97a shows no increased sensitivity to mutagens when compared with TA1537 and (iii) nearly all the limited published database is for the original isolate, TA97, rather than TA97a, and the results obtained here indicate significant differences in response between the two; TA97a remains, therefore, essentially unvalidated.