Bacteria isolated from explosive contaminated environments transform pentaerythritol tetranitrate (PETN) under aerobic and anaerobic conditions

Abstract

Pentaerythritol tetranitrate (PETN) is a nitrate ester explosive that may be persistent, with scarce reports on its environmental fate and impacts. Our main objective was to isolate and characterize bacteria that transform PETN under aerobic and anaerobic conditions. Biotransformation of PETN (100 mg L−1) was evaluated using mineral medium with (M+C) and without (M-C) additional carbon source under aerobic conditions, and with additional carbon source under anaerobic conditions. Here we report on the isolation of 12 PETN transforming cultures (4 pure and 8 co-cultures) from environmental samples collected at an explosive manufacturing plant. The highest transformation of PETN was observed for cultures in M+C under aerobic conditions, reaching up to 91±2% in 2 days. Under this condition, PETN biotransformation was observed in conjunction with the release of nitrites and bacterial growth. No substantial transformation of PETN (<45%) was observed during 21 days in M-C under aerobic conditions. Under anaerobic conditions, five cultures could transform PETN (up to 52±13%) as the sole nitrogen source, concurrent with the formation of two unidentified metabolites. PETN-transforming cultures belonged to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Actinobacteria. In conclusion, we isolated 12 PETN-transforming cultures belonging to diverse taxa suggesting that PETN transformation is phylogenetically widespread.