DETERMINATION OF MUTATIONAL SPECTRUM OF THE PESTICIDE, CAPTAN, WITH AN IMPROVED SET OF ESCHERICHIA-COLI LACZ MUTANTS

The mutational spectrum of the fungicide, captan, was determined using a. set of improved Escherichia coli lacZ mutants. Captan created muta tions mostly at dA-dT sites (83%) with only 17% occurring at dG-dC sit es. The hydrolysis products of captan do not appear to be mutagenic be cause samples of captan at different hydrolysis stages showed basicall y the same mutational spectra: 31% of AT --> CG transversions, 8% of G C --> AT transitions, 2% of GC --> CG transversions, 8% of GC --> TA t ransversions, 19% of AT --> TA transversions, and 32% of AT --> GC tra nsitions. Prepared solutions of captan lost their mutational activity gradually over time, indicating that the rate of decrease in mutagenic ity agreed with the kinetics of captan hydrolysis reported in other st udies. Using the change in mutagenicity to predict degradation, the hy drolysis of captan in pH 7.0 buffer was about three times faster than the hydrolysis carried out in pH 4.5 buffer. To our knowledge, this is the first presentation of mutational spectrum of captan.