Bacterial Communities in Marine Salt Evaporate Rocks and Pristine Zechstein Aquifers

Abstract

ABSTRACTSubsurface microorganisms dependent on local geological conditions of three groundwater wells reaching into Zechstein were investigated. An overlapping diversity could be shown, even if the wells have probing depths and belong to different locations in the Werra region, Germany. Actinobacteria is by far the most abundant phylum, followed by Proteobacteria. The most important differentiating factor between the groundwater aquifers was salt concentration, with increasing salinity leading to a decrease in bacterial abundance. The influence of Buntsandstein overlaying the Zechstein could be clearly seen with the aquifers, indicating mixed and diluted groundwater. A comparison of the isolated groundwater bacteria with those from salt samples of their lithostratigraphic origin in the marine evaporate rocks revealed lower cell counts and diversities of those microorganisms entrapped in the salt crystals, likely remaining from salt deposition during the Permian period. Similar prokaryotes were detected from both habitats, showing that Bacillus, Brevibacterium, and Oceanobacillus species are capable of surviving in extreme saline habitats and are typical representatives for Zechstein deposits.