Gene library for seabed microbes
The production of methane and its breakdown by microbes in the seabed is an important source of greenhouse gas emissions. In line with this, the METROL project investigated seafloor methane production. Field studies and observations were undertaken in the Baltic, North and Black Seas. There are three main groups of microorganisms involved in the efflux of methane from seeps at deep-sea level. Firstly, there are the microbes that are responsible for the anaerobic oxidation of methane (AOM) to produce methanol. This process dramatically reduces the level of methane seepage. Another important group are the Archaea; these are microbes directly responsible for methane production that are known as methanogens. They derive their energy from the production of methane and their presence is linked biochemically to the sulphate-reducing bacteria. These last two groups are associated with the sulphate-methane transition zone (SMTZ) sediments. Identification of the microbes together with a measure of their diversity and community structure was performed by means of DNA identification. The DNA isolated from the sites in question was amplified and compared with gene databases from other deep-water seeps. To study the microbial diversity, six gene libraries have been constructed - three for the bacteria and the same number for the Archaea. All samples were taken from the SMTZ of methane seeps. Archaeal diversity was as high as for the bacteria indicated by six different phylogenetic groups of Archaea. Very similar groups as those known from deep water seep sites were found and this further supports the presence of a cosmopolitan microbial population of AOMs in these zones. Potential users of this information, including molecular biologists involved in bioinformatics and microbiologists working on these microbes, will have access to the gene banks for reference purposes. The results will also help to improve general understanding of natural chemical environments and their effects on biology.
