Bacterial composition of the biofilm on valves of Limnoperna fortunei and its role in glyphosate degradation in water

FLÓREZ VARGAS, RP; SAAD, JF; GRAZIANO, M; DOS SANTOS AFONSO, M; IZAGUIRRE, I; CATALDO, D

AQUATIC MICROBIAL ECOLOGY

INTER-RESEARCH

Año: 2019 vol. 83 p. 83 - 94

0948-3055

Knowledge of the anthropogenic drivers of environmental change is important forunderstanding ecosystem dynamics. We studied 2 of these factors?an invasive mollusk (goldenmussel Limnoperna fortunei) and the herbicide glyphosate?focusing on the effects of the mussel,the herbicide, and their interaction on the abundance and composition of different groups of biofilmbacteria present on the mussel?s valves. We carried out semi-static experiments to assesschanges in nutrient and glyphosate concentrations in the presence or absence of the mussel. Thecatalyzed reporter deposition-fluorescence in situ hybridization technique was used to evaluatechanges in biofilm bacteria growing on whole mussels or dissected valves. When the mussel wasexposed to glyphosate, there was a significant decrease in the concentration of the herbicide, asignificant increase in the concentration of its major metabolite (aminomethylphosphonic acid),and a significant increase in the concentration of nutrients. These results may be explained by thecapacity of biofilm bacteria associated with L. fortunei to degrade glyphosate. After exposure tothe herbicide, the analysis of 5 groups of Eubacteria (i.e. Alpha-, Beta-, and Gammaproteobacteria,Actinobacteria, and Bacteroidetes) showed a significant increase in the abundance ofGammaproteobacteria, suggesting that they would participate in glyphosate transformation inwater. This study represents a starting point for investigating the bacterial component of the biofilmpresent on the valves of L. fortunei. Moreover, this invasive mussel is a promising tool forglyphosate degradation. However, the liberation of nutrients as a consequence of the degradationof herbicide mediated by the presence of L. fortunei may accelerate eutrophication processes infreshwater ecosystems