Caracterização taxonômica e funcional de consórcios microbianos degradadores de glifosato e sua atividade em microcosmos de solo

Abstract

Glyphosate, a widely used non-selective herbicide, can affect non-target plants and soil ecosystems, raising environmental and toxicity concerns. Therefore, remediation of contaminated areas is essential, with microbial enzymatic catalysis being the most effective approach. This study aimed to establish a microbial consortium through enrichment using glyphosate as the sole carbon source and to characterize it through metataxonomic (16S rRNA gene) and metagenomic (genomic binning approach) methods. Additionally, the study sought to evaluate the degradation potential of these consortia in soil microcosms, using microbial activity as an indirect indicator of the degradation process. Soil samples were collected from Conilon and Arabica coffee plantations in Espírito Santo, Brazil, which employed different weed management practices. Aliquots from soil samples and enrichment units were collected for analysis of microbial community succession, utilizing high-throughput DNA sequencing approaches. Furthermore, genome recovery protocols were applied to the established bacterial consortia, followed by annotation of genes encoding key enzymes involved in glyphosate and AMPA degradation. In the microcosms, CO2 production was monitored over 140 hours to assess the catabolic activity in soils inoculated with the consortia and in non-inoculated controls. 16S rRNA gene analyses were conducted to investigate changes in microbial community structure after 140 hours. The enrichment process revealed dynamic alterations in the microbial community composition over time, with Achromobacter sp. and Serratia sp. standing out for possessing the metabolic repertoire required for glyphosate and aminomethylphosphonic acid (AMPA) mineralization. The tested bacterial consortia demonstrated high catabolic activity, especially those cultured with glyphosate as a phosphate source before inoculation in the soil microcosms. Differential abundance analysis showed significant increases in Achromobacter and Serratia in inoculated soils compared to controls, alongside other herbicide-degrading genera, such as Arthrobacter, Paenarthrobacter, and Pseudarthrobacter. These findings suggest the potential of the T6 consortium for the remediation of glyphosate-contaminated soils, though environmental safety tests remain necessary.