uncultured prokaryote Raw sequence reads

In this study, we aim to understand environmental and microbial signatures indicative of RDX degradation in groundwater. First we surveyed the microbial profile of a RDX-contaminated groundwater sample from a perched-intermediate aquifer using 16S rRNA profiling. A total of 1605 operational taxonomy units (OTUs) in 96 genera was identified suggesting high level of microbial diversity. Phylogenetic analysis revealed that the groundwater harbored diverse groups of Rhodococcus and Pseudomonas including some related to RDX-degradation. To identify factors enhancing microbial activity and RDX degradation, groundwater samples were cultivated with acetate and vegetable oil. Results demonstrated that vegetable oil but not acetate promoted RDX degradation under anaerobic conditions. Upon addition of carbon sources, dominant members of Nocardiaceae were outcompeted by bacteria in the family of Comamonadaceae and Pseudomonadaceae, which were underrepresented in groundwater. One of the retrieved sequences related to a previously described RDX-degrading strain (99% sequence identify) was enriched by vegetable oil under anaerobic conditions. Our data also highlight the importance of oxygen in shaping the microbial community during biostimulation. The results of this study expand our current understanding of microbial ecology in RDX-contaminated aquifers and emphasize the potential importance of microbes in RDX transformation.