In this project, studies will be conducted to establish why RDX persists in soil and surface run-off. In addition, it is important to develop a better understanding of the microbial detoxification pathways for NTO. These findings will be used to develop, and test, biotechnologies that can be deployed in the field to enhance RDX degradation in soils and reduce RDX in surface run-off. The specific objectives of this project are to:
Experiments will determine the mechanism by which the co-contaminant, 2,4,6-trinitrotoluene (TNT), inhibits the RDX-degrading enzyme cytochrome P450-like protein (XplA). This information will be used to produce new TNT-insensitive XplA variants for future remediation technologies. Microcosm studies will be used to determine factors preventing the establishment and proliferation of XplAB-containing bacteria in RDX-contaminated range soils. The effect of practical amendments such as compost and manure will be investigated to assess whether these would be effective in-the-field. Phylogenetically, the xplAB gene system is currently limited to members of the order, Actinomycetales. Existing technologies will be further developed to facilitate the promiscuous, horizontal gene transfer of xplAB between diverse family of soil bacteria, particularly members of the Pseudomonadaceae which are known to populate RDX-contaminated soils. Following the experiments on soil bacteria, rhizospheric and endophytic bacteria will be isolated from plant species indigenous to, and growing on, military range soils. The xplAB genes will then be transferred to these rhizospheric and endophytic Pseudomonadaceae using the optimized horizontal gene transfer technologies. The transformed bacteria containing xplAB will be applied to soil microcosms to determine the ability of these species to remediate RDX.
The results from this project will significantly increase the understanding of RDX persistence in the environment and help to develop management strategies applicable to conventional and insensitive munitions. (Anticipated Project Completion - 2024).
Cary T.J., E.L Rylott, L. Zhang, R.M. Routsong, A.J. Palazzo, S.E. Strand, and N.C. Bruce. 2021. Field Trial Demonstrates Phytoremediation of the Military Explosive RDX by XplAB-expressing Switchgrass. Nature Biotechnology, 39:1216-1219. doi.org/10.1038/s41587-021-00909-4.
Rylott, E.L. and N.C. Bruce. 2020. How Synthetic Biology Can Help Bioremediation. Current Opinion in Chemical Biology, 14: 86-95.
Rylott, E.L. and N.C. Bruce. 2022. Plants to Mine Metals and Remediate Land. Science, 377: 1380-1381.
Rylott, E.L. and N.C. Bruce. 2019. Right on Target: Using Plants and Microbes to Remediate Explosives. International Journal of Phytoremediation, 10: 1-14.
Williams E.M., A.V. Sharrock, E.L. Rylott, N.C. Bruce, J.K. MacKichan, and D.F. Ackerley. 2019. A Cofactor Consumption Screen Identifies Promising NfsB Family Nitroreductases for Dinitrotoluene Remediation. Biotechnology Letters, 41: 1155-1162.