Effects of the herbicide molinate on the metabolic activities of a degradative Streptomyces griseus strain

Cometabolic degradation of the herbicide molinate was tested using two microorganisms, Arthrobacter sp., strain M3 and Streptomyces griseus strain M2; the latter classified on the basis of the presence of the enzymatic cofactor SF-420. The strains M3 and M2, inoculated in a basic salts medium with glucose as carbon source and added with 100 mg L(-1) of molinate, degraded respectively 35 and 51% of the herbicide in 36 days. Increasing concentrations of molinate, ranging from 50 to 200 mg L(-1) in glucose medium, did not affect the final ATP yield ofthe strain M2, but decreased the final growth yield and the ATP synthesis rate. Moreover, the onset of coenzyme SF-420 synthesis was progressively delayed. In contrast, surprisingly, SF-420 final yield and production rate were increased by progressive increasing concentrations of molinate in the mineral medium.