Unraveling the microbial community of a cold groundwater catchment system.

ABSTRACT

The abundance, diversity and composition of bacterial communities in water wells with low groundwater temperatures were assessed. The drinking water catchment system, equipped with subsurface groundwater treatment for iron- and manganese removal, is located within a continental influenced veldt landscape type in eastern Russia, close to the border to China. In this study, the bacterial communities in 22 different water wells of the catchment system were analyzed and correlated to operating conditions and environmental factors. The investigated bacterial treated and groundwater populations differed from those in central European groundwater. Large variations between the investigated samples were observed, and DGGE profiles of water samples from the beginning and the end of the abstraction phases revealed two distinct fingerprint clusters with about 82% similarity to each other corresponding to the operation mode of the wells. Sequence data analysis from 454 pyrosequencing indicated Rhodoferax and Gallionella as the most abundant genera within the catchment system. The abundance of the OTU Methylotenera was statistically significant when correlated to the beginning of the abstraction phases, while no indicator OTUs could be determined for the end of the pumping phases. ACK-M1 cluster was proofed as indicator OTU for operating wells, whereas the Gallionella OTUs were correlated with non operating wells. Well operation and resultant oxygen entry could serve as factors that altered the bacterial community structure and composition the most. Quantitative PCR analysis showed that genes related to the iron-reducing Rhodoferax genus were present in nearly all of the samples. This study clearly showed an alteration within the bacterial communities dependent on the operation mode of the water wells.