Other

PRJEB13658

Numerous investigations of microbial communities using sequence analysis of environmental DNA have revealed extensive diversity of microbial taxa in an array of different environmental habitats. Community analysis based solely on total DNA, however, does not reveal whether the detected community members are actively contributing to community functioning, or whether they are dormant or remnants of dead cells. This dilemma is of particular concern when analysing microbial community structure of the seafloor of the Baltic Sea’s deepest point, the Landsort Deep. This site consists of anoxic sediments with a high deposition of accumulating organic matter from the highly stratified 460 m water column above. Our previous metagenomics results showed that these sediments hold a diverse microbial community, but which community members were active was however not evident. To get insight into the composition of the active community, we here present ratios of 16S rRNA to 16S rRNA genes as a proxy for the protein synthesis potential of the community members. Variation in protein synthesis potential was large both within and between taxa in the sediment community. Many typically anaerobic taxa, e.g. from Deltaproteobacteria and Euryarchaeota, show high protein synthesis potential. More surprisingly, some common Baltic Sea surface water bacteria also show protein synthesis potential in the anoxic sediment at 460 m depth. Both filamentous and unicellular Cyanobacteria exhibit very high protein synthesis potential, which implies a more complex role of these bacteria in carbon cycling in the Baltic Sea than previously thought. Moreover, Mycobacteria – abundant in Landsort Deep sediment metagenome compared with other marine sediment metagenomes – show protein synthesis potentials consistent with a functional role in the sediment community. Our results provide a new window of insight into the complexities of anoxic sediment microbial communities of Landsort Deep.(16S rDNA data)

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NCBI

SCR:006472

National Center for Biotechnology Information

SCR:004801

NCBI BioProject