Interactions during fermentation between pesticides and oenological yeasts producing H₂S and SO₂

The degradative action of two strains of Saccharomyces cerevisiae, producers of large quantities of H2S and SO2, on eight sulphur-containing insecticides (chlorpyrifos-methyl, dimethoate, fenitrothion, fenthion, malathion, methidathion, parathion, and quinalphos) was studied. Moreover, the influence of these compounds on the fermentative activity of the yeasts was investigated. The yeasts adsorbed and degraded the studied insecticides to various extents, but their fermentative activity was not affected. A moderate adsorption (approximately 10% of the residue) was observed for chlorpyrifos-methyl, fenitrothion, parathion, and quinalphos. When adsorbed, the insecticides were also degraded by about 50%. The degraded pesticides belong to the thiophosphates, while the dithiophosphates showed higher stability. The two yeast strains showed analogous degradative actions