Suspended and attached bacterial communities in limestone aquifers

In this study we investigated the community structure of groundwater bacteria in two superimposed limestone aquifer assemblages in the Hainich region (Thuringia/Germany). Samples were obtained from 8 different wells along a groundwater observation transect with sampling depth ranging from 12 to 88 m depth. Community structure was assessed by 454 amplicon pyrosequencing, targeting the V1-V3 region of the bacterial 16S rRNA gene. Sequencing was performed on both the DNA and RNA level for groundwater samples and additionally for samples of microbial populations which had attached to cleaved rock material exposed in situ in two groundwater wells. Sequencing of attached microbial populations was only carried out on the DNA level.