<title>Abstract</title> Pentaerythritol tetranitrate (PETN) is a nitrate ester explosive, true xenobiotic, recalcitrant and persistent compound in the environment. Our main objective was to isolate bacteria from environmental samples collected at an explosive manufacturing plant with the capacity to transform PETN (100 mg L<sup>− 1</sup>) under aerobic and/or anaerobic conditions. Biotransformation of PETN was evaluated using mineral medium without (M-C) and with additional carbon (M + C) source under aerobic conditions, and with additional carbon source under anaerobic conditions. Here we report on 12 cultures (4 pure and 8 co-cultures) with the capacity to transform PETN. 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 observer in conjunction with the release of nitrites and bacterial growth, measured as optical density and total proteins. No substantial transformation of PETN (< 45%) was observed during 21 days in M-C under aerobic conditions. Under anaerobic conditions, five cultures reached up to 52 ± 13% PETN biotransformation in 160 days, concurrent with the formation of two unidentified metabolites. PETN-transforming cultures belonged to<italic>Alphaproteobacteria</italic>,<italic>Betaproteobacteria</italic>,<italic>Gammaproteobacteria</italic>and<italic>Actinobacteria</italic>. In conclusion, we isolated 12 PETN-transforming cultures belonging to diverse taxa suggesting that PETN transformation is phylogenetically widespread.
