Microbial hydrogen oxidation potential in seasonally hypoxic Baltic Sea sediments
Coastal regions can be seen as hot spots for the degradation of organic matter on the seafloor . Since oxygen quickly becomes depleted in the surficial sediments, most of the OM decomposition is driven by microbial sulfate reduction and fermentation, generating molecular hydrogen. If the hydrogen is not consumed by hydrogenotrophic microorganisms and accumulates in the sedimentary pore waters, organic matter degradation is hindered. Despite the importance of hydrogen scavenging microorganisms on organic matter mineralization, the knowledge on hydrogen oxidizers and their constraints in coastal marine sediments is still quite limited. Here we investigated the role of hydrogen oxidizers in top (2 to 5 cm) and bottom (18 to 22 cm) coastal sediments, retrieved in three different months from a location exposed to seasonally hypoxic bottom waters in the SW Baltic Sea.