|Abstract Title:||Multi-Omics Reveals Metabolically Versatile Bacterial Mercury Methylators in Marine Oxycline|
|Presenter Name:||Heyu Lin|
|Company/Institution:||The University of Melbourne|
|Session:||Special Session - Meta-omic and geochemical approaches to linking microbial activity to biogeochemical mercury cycling|
|Day and Session:||Friday 29th July - Session One|
|Start Time:||06:00 UTC|
Abstract Information :
Methylmercury (MeHg) is a potent neurotoxin that bioaccumulates in marine environments. The production of MeHg is a microbially-mediated process requiring the hgcAB gene pair long considered to be carried by anaerobic microorganisms. However, recent studies have demonstrated the potential for MeHg production in low-oxygen aqueous environments, although the microbes responsible for methylation remain largely unknown. In this study, we performed large-scale multi-omic analyses of well-defined redox gradients in Saanich Inlet (SI), British Columbia, to study the potential for Hg methylation and the putative metabolic traits of Hg methylators. Calditrichaeota, SAR324 and Marinimicrobia were identified from metagenomes as putative new Hg methylating groups in SI, in which Marinimicrobia showed the highest level of hgcA transcription. Putatively novel HgcAB proteins were also detected in the metaproteomic dataset. The functionality of Marinimicrobia-hgcAB genes was validated by protein homology modelling and these genes were further found in multiple public metagenome datasets, supporting a key role in marine Hg cycling. Furthermore, the genomic capabilities of these new Hg methylators were studied and indicated a degree of oxygen tolerance. Our findings thus reveal previously unrecognized marine microbial Hg methylators with a greater oxygen tolerance and broader habitat.