Uncovering the structure and function of specialist bacterial lineages in environments routinely exposed to explosives.

Environmental contamination by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), the two most widely used compounds for military operations, is a long-standing problem at the manufacturing and decommissioning plants. Since explosives contamination has previously been shown to favour the growth of specific bacterial communities, the present study attempts to identify the specialist bacterial communities and their potential functional and metabolic roles by using amplicon targeted and whole-metagenome sequencing approaches in samples collected from two distinct explosives manufacturing sites. We hypothesize that the community structure and functional attributes of bacterial population are substantially altered by the concentration of explosives and physicochemical conditions. The results highlight the predominance of Planctomycetes in contrast to previous reports from similar habitats. The detailed phylogenetic analysis revealed the presence of operational taxonomic units related to bacterial members known for their explosives degradation. Further, the functional and metabolic analyses highlighted the abundance of putative genes and unidentified taxa possibly associated with xenobiotic biodegradation. Our findings suggest that microbial species capable of utilizing explosives as a carbon, energy or electron source are favoured by certain selective pressures based on the prevailing physicochemical and geographical conditions.