Glyphosate in vitro removal and tolerance by Aspergillus oryzae in soil microcosms

Abstract

Argentinian agriculture is based on a technological package that includes the application of significant amounts of pesticides. Glyphosate is the active ingredient of several glyphosate herbicides which are frequently used for weed control. Fungi can use glyphosate both as a nutrient and an energetic source. Therefore, the aim of the present study was to evaluate the in vitro glyphosate removal as the only source of phosphorus or nitrogen by two non-toxigenic Aspergillus oryzae strains. A. oryzae AM1 and AM2 were successfully able to use the herbicide both as phosphorus or nitrogen source. The degradation percentages were higher than 50% at the end of the incubation period (15 days) with glyphosate concentrations of 1 and 1.5 mM. In addition, AM1 strain was able to remove 57% of 10 mM of glyphosate at 0.99 of aW. Soil microcosm assay was performed in order to study the GP tolerance, permanence and competitiveness of A. oryzae AM1 in the presence of native mycota. A. oryzae count remained constant along the incubation period and was not significantly affected by the different glyphosate concentrations tested (10, 20 and 50 mM). This strain showed great in vitro removal ability, and it was also able to remain viable on soil microcosms contaminated with glyphosate. Therefore, these results encourage future studies in order to evaluate the ability of these strains to degrade glyphosate on soil and then promote them as potential bioremediation agents.