Mercury-methylating bacteria are associated with copepods: A proof-of-principle survey in the Baltic Sea

Gorokhova, ElenaStockholms universitet,Institutionen för miljövetenskap,Stockholm University, Department of Environmental Science (author)

Mercury-methylating bacteria are associated with copepods : A proof-of-principle survey in the Baltic Sea

Methylmercury (MeHg) is a potent neurotoxin that biomagnifies in marine food webs. Inorganic mercury (Hg) methylation is conducted by heterotrophic bacteria inhabiting sediment or settling detritus, but endogenous methylation by the gut microbiome of animals in the lower food webs is another possible source. We examined the occurrence of the bacterial gene (hgcA), required for Hg methylation, in the guts of dominant zooplankters in the Northern Baltic Sea. A qPCR assay targeting the hgcA sequence in three main clades (Deltaproteobacteria, Firmicutes and Archaea) was used in the field-collected specimens of copepods (Acartia bifilosa, Eurytemora affinis, Pseudocalanus acuspes and Limnocalanus macrurus) and cladocerans (Bosmina coregoni maritima and Cercopagis pengoi). All copepods were found to carry hgcA genes in their gut microbiome, whereas no amplification was recorded in the cladocerans. In the copepods, hgcA genes belonging to only Deltaproteobacteria and Firmicutes were detected. These findings suggest a possibility that endogenous Hg methylation occurs in zooplankton and may contribute to seasonal, spatial and vertical MeHg variability in the water column and food webs. Additional molecular and metagenomics studies are needed to identify bacteria carrying hgcA genes and improve their quantification in microbiota.

Sörensen, Anne L.Naturhistoriska riksmuseet,Stockholms universitet,Institutionen för miljövetenskap,Enheten för miljöforskning och övervakning,Stockholm University, Department of Environmental Science(Swepub:su)annes (author)
Motwani, Nisha H.Södertörns högskola,Miljövetenskap,Stockholm University, Department of Environmental Science(Swepub:sh)shnami18 (author)
Stockholms universitetInstitutionen för miljövetenskap (creator_code:org_t)

By the author/editor: Gorokhova, Elena; Sörensen, Anne L ...; Motwani, Nisha H ...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Earth and Relate ...; and Environmental Sc ...

By the university: Södertörn University; Stockholm University; Swedish Museum of Natural History

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