Colonization of carbonate rocks by groundwater bacteria

This study aims to provide insights into the groundwater microbial communities colonizing carbonate rocks. Rock chips were prepared from altered limestone surfaces from rock matrices belonging to the Upper Muschelkalk (Germanic Triassic, Trochitenkalk formation). Half of them were coated with iron oxides, mimicking secondary mineral formations commonly found in fractures of the carbonate rocks. These chips were incubated in bioreactors fed by oxic or anoxic groundwater to: (1) follow the attachment and abundance of carbonate rocks by groundwater bacteria over time; and (2) to determine the composition and potential functions of the attached bacteria. For comparison, crushed limestone rock material was exposed as passive samplers both in two wells reaching either the oxic or anoxic groundwater.