Isolation of culturable mycota from Argentinean soils exposed or not-exposed to pesticides and determination of glyphosate tolerance of fungal species in media supplied with the herbicide

Abstract

The current agricultural system has led to the development of glyphosate (GP)-resistant weeds, causing an increase in GP doses and applications. Native mycota of pesticide-contaminated sites are the major source of pesticide-degrading microorganisms. The aims of the present study were to isolate the GP-tolerant culturable mycota in two soils with different pesticide exposure from Córdoba, Argentina, and to evaluate the growth parameters in native fungal isolates in the presence of GP and the effective dose that caused 50% growth reduction. The results showed that the genera Fusarium, Aspergillus, Mucor, Penicillium and Sterilia were the prevalent fungi isolated from soils both exposed and not-exposed to pesticides. The highest value (>100mM) of effective concentration of herbicide that caused 50% growth inhibition (EC50), was found for Trichoderma isolates. Sterilia spp. had EC50 values of 100mM, while Aspergillus spp. and Mucor had EC50 values between 50 and 100mM. The growth rate evaluation varied according to the isolates and GP concentrations. The data showed that all Aspergillus spp., Trichoderma spp., Mucor and three Sterilia spp. had the best growth performance in media supplied with GP after a variable acclimation period. This study provides valuable data for further studies that would allow to know the metabolic capacity of these fungal species that can be potential candidates for GP removal from contaminated environments.