Mutagenicity and DNA-damaging activity for several pesticides tested with Bacillus subtilis mutants

Area of Science:

• Environmental toxicology
• Microbial genetics
• Chemical safety

Background:

• Pesticide safety assessment relies on mutagenicity testing.
• Traditional methods using Salmonella typhimurium may not detect all mutagenic compounds.
• Developing sensitive and reliable mutagenicity assays is crucial for public health.

Purpose of the Study:

• To compare the mutagenic and DNA-damaging activities of four pesticides using Bacillus subtilis and Salmonella typhimurium.
• To evaluate the efficacy of B. subtilis strain TKJ6321 for detecting mutagenicity.
• To determine the necessity of metabolic activation for these pesticides.

Main Methods:

• Tested four pesticides: dithane, maleic hydrazide, malathion, and fumazone.
• Utilized Bacillus subtilis strain TKJ6321 and Salmonella typhimurium tester strains.
• Assessed mutagenicity with and without rat-liver S9 metabolic activation.
• Evaluated DNA-damaging activity using repair-deficient B. subtilis mutants.

Main Results:

• All four pesticides showed mutagenic responses in B. subtilis, while Salmonella tests yielded weak or negative results.
• Dithane exhibited strong mutagenicity, while fumazone, maleic hydrazide, and malathion showed moderate mutagenicity.
• Only fumazone required metabolic activation, producing a volatile mutagenic product.
• Dithane demonstrated significant DNA-damaging activity in repair-deficient B. subtilis mutants.

Conclusions:

• Bacillus subtilis is more sensitive than Salmonella typhimurium for detecting the mutagenicity of these pesticides.
• B. subtilis strain TKJ6321 is a valuable tool for prescreening pesticide mutagenicity.
• Combined use of B. subtilis and S. typhimurium offers a comprehensive approach to mutagenicity assessment.