RDX degrading microbial communities and the prediction of microorganisms responsible for RDX bioremediation

The explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has caused significant soil and groundwater contamination. To remediate these sites, there is a need to determine which microorganisms are responsible for in situ biodegradation of RDX to enable the appropriate planning of bioremediation efforts. Here, studies are examined that have reported on the microbial communities linked with RDX biodegradation. Dominant microorganisms across samples are discussed and summarized. This information is then compared to current knowledge on RDX degrading isolates to predict which organisms may be responsible for RDX degradation in soils and groundwater. From the phyla with known RDX degrading isolates, Firmicutes and Proteobacteria (particularly Gammaproteobacteria) were the most dominant organisms in many contaminated site derived samples. Organisms in the phyla Deltaproteobacteria, Alphaproteobacteria and Actinobacteria were dominant in these studies less frequently. Notably, organisms within the class Betaproteobacteria were dominant in many samples and yet this class does not appear to contain any known RDX degraders. This analysis is valuable for the future development of molecular techniques to track the occurrence and abundance of RDX degraders at contaminated sites.