Using stable isotope probing to characterize differences between free-living and sediment-associated microorganisms in the subsurface

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Taylor & Francis for personal use, not for redistribution. The definitive version was published in Geomicrobiology Journal (2013): 362-370, doi:10.1080/01490451.2012.689090.Aquifers are subterranean reservoirs of freshwater with heterotrophic bacterial communities attached to the sediments and free-living in the groundwater. In the present study, mesocosms were used to assess factors controlling the diversity and activity of the subsurface bacterial community. The assimilation of 13C, derived from 13C-acetate, was monitored to determine whether the sediment-associated and free-living bacterial community would respond similarly to the presence of protozoan grazers. We observed a dynamic response in the sediment-associated bacterial community and none in the free-living community. The disparity in these observations highlights the importance of the sediment-associated bacterial community in the subsurface carbon cycle.This research was supported by NSF grant EAR-0525166 to EBK