Glyophosate-degradation-products Metagenome

Widely-used glyphosate may produce AMPA, glycine and sarcosine degradation products. To date, little is known about effects of these degradation products on soil microorganisms and their potential degraders. Here, we incubated a soil spiked either with 13C-labeled glyphosate, AMPA, sarcosine or glycine for 75 days. During this period, soil respiration rates (CO2) and mineralization rates of the compound (13CO2) were estimated in addition to phospholipid fatty acids (PLFAs and 13C-PLFAs) as biomarkers to identify major groups of microorganisms in soil. 16S/ITS rRNA amplicon sequencing was also conducted to identify the microbial community structures and underlying functions. Soil respiration, mineralization rates, microbial biomass (PLFAs) as well as incorporation of 13C into PLFAs were highest for glycine and lowest for AMPA. Results demonstrated that Gram negative degraders were major degraders of each compound, whereas Gram-positive bacteria, actinobacteria and fungi (Ascomycota phylum) were decomposers of the primary degraders. Based on similar time-dependent shifts in (13C-)PLFAs and abundances of 16S rRNA genera, we deduced that glyphosate was mainly degraded to glycine. However, stable isotope metagenomics or proteomics investigating the capability of specific bacterial/fungal genera to degrade glyphosate to either glycine or to AMPA product are still needed.