Biochemical and Microbial Analysis of Ovine Rumen Fluid Incubated with 1,3,5-Trinitro-1,3,5-triazacyclohexane (RDX)

Abstract

In this study, the rumen was assessed for its potential to detoxify RDX using molecular microbial ecology as well as analytical chemistry techniques. Results indicated significant loss (P < 0.05) of RDX in <8-h post incubation, and qualitative LC-MS/MS analysis showed evidence for the formation of 1-NO-RDX (M-O + HCOO) and methylenedinitramine metabolites. A total of 1106 16S rRNA-V3 clones were sequenced, and most sequences associated with either the phyla Bacteroidetes or Firmicutes. A LibCompare analysis for the RDX treatment showed an enrichment (P < 0.01) of the genus Prevotella. From these results, it can be concluded that the rumen is capable of detoxifying RDX, and the members of the genus Prevotella are linked to this detoxification.

Metagenomic Insights into the RDX-Degrading Potential of the Ovine Rumen Microbiome

“…6% of the initial RDX remained. The rapid degradation of RDX by the ovine rumen microbiome is in agreement with previous observations [27]. The rumen microbiome was sampled for metagenomic analysis from four of the six time points tested (10, 60, 150 and 240 min).…”

“…One possible explanation is that measurable changes in the microbial community composition or metabolic potential may take time to develop, and a four-hour incubation might not be sufficient to induce any changes. Significant changes induced by RDX in the number of sequences assigned to the genus Prevotella did not show up until eight-hour post-incubation in the rumen, when the substrate was no longer available [27]. However, the most likely explanation is that the RDX-degrading capacity of the ovine rumen microbiome is regulated at the transcriptional level.…”

“…For example, a significantly higher number of 16S rRNA gene sequences assigned to the genus Prevotella was observed in the ovine rumen after 8 h of incubation compared to 4 h [27]. In groundwater samples, the production of RDX metabolites corresponds to a microbial community shift from one made up of primarily β-Proteobacteria to a community dominated by δ-Proteobacteria [47].…”

“…Greater than 98% of RDX is biotransformed from its initial concentration of 25 µg/µl within four hours of incubation. By the end of an eight-hour incubation, RDX cannot be detected using traditional detection methods, high-performance liquid chromatography (HPLC) and LC-MS/MS [27]. Thus far, the unique anaerobic environment of the rumen, with its high redox potential, appears to be highly efficient at biodegrading RDX, and RDX-degrading bacteria have been identified from the rumen [11], [27].…”

Feasibility of Co-Treating Olive Mill Wastewater and Acid Mine Drainage

“…Although this family is not normally mentioned as being important for the bioremediation of recalcitrant pollutants, this and other published work support that idea. For example, in a study to assess the potential of rumen microbiome to detoxify hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), an explosive that causes severe environmental contamination, it was concluded that members of the genus Prevotella were linked to its detoxification (Perumbakkam and Craig 2012). A study based on 16S rRNA gene libraries constructed using PCR primers for β-Proteobacteria to identify bacterial diversity in OMWW revealed that bacterial diversity in O. europaea var.…”