Taxonomic Composition and Functional Potential of the Anaerobic Microbial Communities of the Tambukan Lake Therapeutic Muds

Analysis of the anaerobic microbial communities from the therapeutic muds of Tambukan Lake performed by molecular and cultivation approaches revealed their high taxonomic diversity. Microorganisms involved in transformations of oxidized and reduced sulfur compounds represented 40–70% of all phylotypes detected by the 16S rRNA gene amplicon sequencing. A significant part of the communities was represented by uncultivated phylotypes belonging to the Desulfurivibrionaceae family, whose members are known to be autotrophic sulfur disproportionators. The enrichment cultures revealed the presence of iron reducers and oxidizers, acetogens and organotrophic bacteria. We identified the key drivers in the biogeochemical cycles of sulfur, iron and carbon, whose activity leads to the formation of the unique Tambukan therapeutic muds.