Tolerance of Bradyrhizobium sp. BR 3901 to herbicides and their ability to use these pesticides as a nutritional source

Several groups of microorganisms degrade and use herbicide residues as a source of carbon and nitrogen. Identification of new strains capable of tolerating and degrading these pesticides can make strategic planning more flexible in environmental decontamination programs. Our objective was to evaluate the tolerance and growth in vitro of Bradyrhizobium sp BR 3901 strain in media without carbon and nitrogen sources, exposed to different herbicides. The biochemical activity of enzymes catalase, esterase, oxidase, reductase, and urease was determined for BR 3901. The time of maximum growth, maximum cell density, and growth in media without carbon and nitrogen sources in the presence of herbicides were evaluated for BR 3901. Formulated products based on glyphosate, sulfentrazone, and diuron were toxic to BR 3901. The presence of glyphosate, sulfentrazone, and diuron decreased maximum cell density and time for maximum cell growth of BR 3901. BR 3901 can use products based on diuron, sulfentrazone, and 2,4-D as a carbon source, even the last two, causing toxicity to this bacterial strain. The oxyfluorfen-based product can serve as a nitrogen source for BR 3901, degrading this pesticide.