Project description:The aim of this study was to identify TBBPA-degrading organisms in a complex microbial community by a metagenome-based functional metaproteomic approach, using protein-based stable isotope probing (protein-SIP). Firstly, the degradation kinetics were evaluated in order to simulate the decrease of residual mass of the labelled compound based on experimental data. In sequence, a metagenome was generated, and biomass was collected in different time-points for protein-SIP in incubations with 13C-TBBPA. This approach allowed for the identification organisms assimilating labelled carbon from the cometabolic degradation of a micropollutant.
Project description:Thiabendazole (TBZ), a benzimidazole used against postharvest fungal growth and as anthelmintic in livestock farming, is highly persistent in soil (DT50> 1-2 years) and therefore challenging concerning its environmental management. In our recent copious attempts to isolate organisms that degrade TBZ, at best, we ended up with a soil microbial enrichment capable of accelerated TBZ degradation. Here, we employed a multi-omic approach combined with DNA stable isotope probing (SIP) for elucidating the underlying system complexity. We obtained 18 high-quality metagenome-assembled genomes, with six being dominant and versatile concerning their putative xenobiotics degradation ability. SIP combined with microbiome analysis verified our previous results about the key role of a Sphingomonas strain in TBZ degradation. Next to this, metabolomics suggested minimal/no cross-feeding events, and Sphingomonas being the sole TBZ degrader. RNA sequencing and proteomics analysis of the consortium using TBZ or succinate as sole carbon sources showed the enhanced expression in Sphingomonas of a carbazole dioxygenase locus with putative role in the TBZ degradation. Gene expression networking analysis suggested the interaction of Sphingomonas with a Hydrogenophaga strain that possibly contributes to the overall cobalamin balance. Our study depicts the need for integrated omic approaches for understanding complex interactions frequently occurring in bioremediation.