Dissolved organic matter does not promote glyphosate degradation in auto-heterotrophic aquatic microbial communities

• Published in: Environmental pollution (1987) Vol. 259; p. 113951
• Main Authors: Artigas, Joan, Batisson, Isabelle, Carles, Louis
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2020; Elsevier
• Subjects: Alphaproteobacteria; Aminomethyl phosphonic acid; antibiotics; aquatic environment; autotrophs; bacteria; Bacteriology; Biodegradation; Biodegradation, Environmental; Biofilm; dissolved organic carbon; Dissolved organic matter; Environmental Sciences; gamma-Proteobacteria; Glycine - analogs & derivatives; Glycine - metabolism; Glyphosate; Herbicides - metabolism; Heterotrophic Processes; heterotrophs; Life Sciences; microbial communities; Microbiology and Parasitology; net primary productivity; Phenylobacterium; phosphorous acid; population size; prokaryotic cells; rivers; Alphaproteobacteria; Biodegradation; Biofilm; Aminomethyl phosphonic acid; Dissolved organic matter
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2020.113951

Environmental dissolved organic matter (DOM) has been proved to increase microbial population sizes and stimulate the degradation of some pesticide molecules. Among these molecules, the present study investigated the biodegradation of the herbicide glyphosate depending on photoautotrophs DOM supply in a microbial consortium isolated from river biofilms. Degradation experiments in the laboratory were performed in dark and light conditions, as well as after antibiotic supply, in order to characterize the eventual interactions between photoautotrophs and heterotrophs activity during glyphosate degradation. Fifty percent of the initial concentration of glyphosate (0.6 mM) was transformed into aminomethyl phosphonic acid (AMPA) after 9 days in presence or absence of light. Accordingly, the photoautotrophic DOM supply was not stimulating glyphosate degradation by microbial heterotrophs. This lack of response was probably explained by the low net primary production values and weak dissolved organic carbon production recorded in light treatments. The supply of the antibiotic drastically stopped glyphosate transformation demonstrating the central role of bacteria in the biodegradation of the herbicide. Glyphosate also modified the structure of prokaryotes assemblages in the consortium by increasing the relative abundances of Alphaproteobacteria and slightly decreasing those of Gammaproteobacteria. The chemoorganotrophic bacteria Phenylobacterium sp. (Alphaproteobacteria) was related to the transformation of glyphosate in our microbial consortium. The present study highlights the complexity of microbial interactions between photoautotrophs and heterotrophs in microbial assemblages that can contribute to the degradation of pesticides present in aquatic environments. [Display omitted] •Bacteria from biofilms had a pivotal role in glyphosate degradation.•Fifty percent of the initial glyphosate was transformed into AMPA after 9 days.•Photoautotrophic DOM did not stimulate glyphosate biodegradation.•Glyphosate modified the structure and composition of bacterial assemblages.•Representatives of Phenylobacterium could be involved in glyphosate degradation. The interaction with DOM of photoautotrophic origin did not influence bacterial degradation of glyphosate.