Sulfate-reducing bacterial communities in the water column of the Gdansk Deep (Baltic Sea)

Biodiversity of sulfate-reducing bacterial communities in the water column of the Gdansk Deep, Baltic Sea, where H2S had been detected in near-bottom layers, was analyzed by PCR with primers for the 16S rRNA genes of six major phylogenetic subgroups of sulfate-reducing bacteria (SRB). Using denaturing gradient gel electrophoresis followed by sequencing, the nucleotide sequences of reamplified dsrB gene fragments from investigated water samples were determined. For the first time the presence of nucleotide sequences of the dsrB gene was detected by PCR in the water samples from all hydrochemical layers, including subsurface oxic waters. The presence of the 16S rRNA genes of representatives of Desulfotomaculum, Desulfococcus-Desulfonema-Desulfosarcina, and Desulfovibrio-Desulfomicrobium SRB subgroups was also revealed throughout the water column of the Gdansk Deep. Analysis of translated amino acid sequences encoded by the dsrB gene demonstrated the highest homology with the relevant sequences of uncultured SRB from various marine habitats.