Response of soil bacterial communities to the application of the herbicides imazethapyr and flumyzin

Abstract

The herbicides imazethapyr and flumyzin have been recommended for controlling weeds, mainly in soybean fields. However, it is unclear the effect of these herbicides on soil microbial communities. In this study, we assessed the responses of bacterial community to the application of imazethapyr and flumyzin in soil. Soil samples were incubated with the application of the herbicides imazethapyr, flumyzin, and their mixture, and analyzed at 0, 15, 30, and 60 days. The abundance of specific microbial phyla changed as a response of the herbicide application with a significant decrease of Acidobacteria, Verrucomicrobia, Elusimicrobia, and Planctomycetes, and an increase of Gemmatimonadetes, Bacteroidetes, Firmicutes, and Proteobacteria. The principal component analysis clustered the samples according to the time of incubation and the microbial diversity increased on the 15th day with a trend to decrease at 30 and 60 days. The evaluation of potential functions has shown the core functions represented by chemoheterotrophy (35.1%), followed by aerobic chemoheterotrophy (32.8%), nitrification (6.2%), ammonia oxidation (6.2%), and aromatic compound degradation (4.4%). Our data showed an increase of microbial groups that have the potential to metabolize the chemical compounds, such as the genera Bryobacter, Gaiella, and Flavobacterium, which increased significantly in abundance and can be explored for future biotechnological use. Finally, this study shows that the application of the herbicides in soil affects the microbial profile with the potential to affect functions mediated by microbial communities, and this effect is related to groups with the potential to degrade the compound.