Augmentation of stimulated Pelomonas aquatica dispersible granules enhances remediation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated soil

Abstract

Abstract In this study, we explored the hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) degradation potential of a gram-negative bacterium Pelomonas aquatica strain 12868. The microbe eliminated 80.68% of RDX by utilizing the explosive as a nitrogen source. FTIR study and nitrite assay confirmed the degradation of RDX into non-toxic metabolites in an RDX-succinate aqueous medium. The isolate showed an improved RDX degradation when formulated into water dispersible granules (WDG) using soy flour as a nutrient source. The WDG formulation not only achieved 6.53% enhanced RDX degradation but also stabilized the microbe as only a 24.37% decrease in cfu count was observed after a storage period of six months at 30 oC. During the microcosm experiments, RDX degradation followed first-order kinetics with a half-life of 13.9 and 19.04 days in a soil biostimulated by sucrose and wheat straw, respectively. P. aquatica with sucrose as added carbon source effectively degraded 50.91% more RDX compared to unstimulated control after 30 days of treatment. These data imply that microbial formulation mediated RDX reduction coupled with biostimulation has the potential to become a swift and sustainable clean-up approach for RDX contaminated environments.