Artificially Constructing Microbial Consortia for Bioaugmentation of Nitroglycerin Degradation

Nitroglycerin (NG), a recalcitrant and highly toxic nitroaromatic pollutant prevalent in wastewater from explosive manufacturing and pharmaceutical sectors, served as the target substrate for developing a synthetic microbial consortium through a bottom-up assembly strategy to enhance its biodegradation efficiency. Through statistical experimental design (DOE) and partial factorial approach (PFA), core strains (X10, X14, X71, X97, and X53) and non-core strains (X55, X88, and X58) were systematically identified. Subsequently, hierarchical stratification of core strains based on their degradation efficiencies toward nitroglycerin (NG) intermediate metabolites was implemented, while a comprehensive full factorial design of non-core strains, was conducted to establish structured microbial consortia X10 + X14 + X97 + X58. Response surface methodology (RSM) optimization identified 28°C, 140 rpm, 0.86 mM initial nitroglycerin (NG) concentration, 1:1:1:1 inoculation ratio, and simultaneous inoculation as the optimal parameters for achieving peak degradation efficiency (90.2 ± 0.8%). Biolog ECO-plate analysis has shown that the consortium can metabolize 31 different carbon sources. Through whole-genome sequencing and metatranscriptome analysis of enzyme genes related to nitroglycerin degradation, the speculation was that strains X10 and X14 were mainly responsible for the degradation of nitroglycerin (NG) to dinitro-glycerin (DNG) and further to mononitro-glycerin (MNG), while strains X97 and X58 were responsible for the degradation of mononitro-glycerin to glycerol, which constituted a complete nitroglycerin degradation pathway.