Research Article Active Microbial Communities Inhabit Sulphate-Methane Interphase in Deep Bedrock Fracture

Copyright © 2015 Malin Bomberg et al.This is an open access article distributed under the Creative CommonsAttribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Active microbial communities of deep crystalline bedrock fracture water were investigated from seven different boreholes in Olkiluoto (Western Finland) using bacterial and archaeal 16S rRNA, dsrB, andmcrA gene transcript targeted 454 pyrosequencing. Over a depth range of 296–798m below ground surface the microbial communities changed according to depth, salinity gradient, and sulphate and methane concentrations. The highest bacterial diversity was observed in the sulphate-methane mixing zone (SMMZ) at 250–350m depth, whereas archaeal diversity was highest in the lowest boundaries of the SMMZ. Sulphide-oxidizin