Formatted Title
Application of Proteomics to Assess Degradation of RDX in Pure Cultures and Groundwater from Impacted Sites
Background/Objectives
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a soluble, nonvolatile cyclic nitramine explosive that has been widely used in military and civilian applications. RDX is also a common groundwater contaminant and a possible human carcinogen. RDX is biodegradable under both aerobic and anaerobic conditions, and several RDX-degrading isolates have been reported. Yet, our understanding of the roles of these known RDX degraders in the environment, the prevalence of RDX degraders in natural or engineered systems, as well as their associated RDX-degrading microbial communities, genes, and proteins in response to engineered interventions, is still developing. A better knowledge of in situ RDX degradation could potentially guide the isolation of novel RDX degraders and the development of suitable biomarkers for monitoring intrinsic or engineered RDX bioremediation. This study used shotgun proteomics to evaluate degradation of RDX by pure cultures of Pseudomonas fluorescence strain IC and Gordonia sp. strain KTR9 with and without an amendment with RDX. Additionally, samples of groundwater from contaminated sites were analyzed to evaluate if the RDX degradation was attributed to naturally occurring microorganisms with the use of transcriptomics, whole genome sequencing and proteomics and use to estimate biodegradation rates for munitions contamination in groundwater.
Approach/Activities
Shotgun proteomics and transcriptomics provide basis to evaluate expression of proteins involved in RDX degradation in pure cultures of RDX degraders. Findings from this experiment have informed on up and down regulation of RDX degradation proteins. Further, shotgun proteomics and metagenomics analyses will be used to evaluate natural attenuation of RDX contaminated sites. This information will help to evaluate the role of continued microbial activity to support ongoing attenuation of residual RDX and to estimate biodegradation rates for munitions contamination in groundwater to facilitate cost effective transitions from active to passive treatment.
Results/Lessons Learned
The proteomics tool applied during this work aids accurate detection of specific peptides in environmental samples as well as has the potential to provide a wealth of new information on protein function and activities within the subsurface. The biomarkers from environmental samples collected from the RDX contaminated sites and the quantitative information will be used to estimate timeframes for RDX degradation. The application of quantitative proteomics and molecular tools will allow site remediation managers to make educated decisions on the course of contaminant treatment for Navy sites.