Transformation of TNT, 2,4-DNT, and PETN by Raoultella planticola M30b and Rhizobium radiobacter M109 and exploration of

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(2020) 36:190

ORIGINAL PAPER

Transformation of TNT, 2,4‑DNT, and PETN by Raoultella planticola M30b and Rhizobium radiobacter M109 and exploration of the associated enzymes Hernán Avellaneda1 · Ziv Arbeli1 · Wilson Teran2 · Fabio Roldan1  Received: 20 June 2020 / Accepted: 11 November 2020 © Springer Nature B.V. 2020

Abstract The nitrated compounds 2,4-dinitrotoluene (2,4-DNT), 2,4,6-trinitrotoluene (TNT), and pentaerythritol tetranitrate (PETN) are toxic xenobiotics widely used in various industries. They often coexist as environmental contaminants. The aims of this study were to evaluate the transformation of 100 mg L ­ −1 of TNT, 2,4-DNT, and PETN by Raoultella planticola M30b and Rhizobium radiobacter M109c and identify enzymes that may participate in the transformation. These strains were selected from 34 TNT transforming bacteria. Cupriavidus metallidurans DNT was used as a reference strain for comparison purposes. Strains DNT, M30b and M109c transformed 2,4-DNT (100%), TNT (100, 94.7 and 63.6%, respectively), and PETN (72.7, 69.3 and 90.7%, respectively). However, the presence of TNT negatively affects 2,4-DNT and PETN transformation (inhibition > 40%) in strains DNT and M109c and fully inhibited (100% inhibition) 2,4-DNT transformation in R. planticola M30b. Genomes of R. planticola M30b and R. radiobacter M109c were sequenced to identify genes related with 2,4-DNT, TNT or PETN transformation. None of the tested strains presented DNT oxygenase, which has been previously reported in the transformation of 2,4-DNT. Thus, unidentified novel enzymes in these strains are involved in 2,4-DNT transformation. Genes encoding enzymes homologous to the previously reported TNT and PETN-transforming enzymes were identified in both genomes. R. planticola M30b have homologous genes of PETN reductase and xenobiotic reductase B, while R. radiobacter M109c have homologous genes to GTN reductase and PnrA nitroreductase. The ability of these strains to transform explosive mixtures has a potentially biotechnological application in the bioremediation of contaminated environments. Keywords  2,4-dinitrotoluene · Biotransformation · Functional library · Genome sequencing · Pentaeritritol tetranitrate · Trinitrotoluene

Introduction

Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s1127​4-020-02962​-8) contains supplementary material, which is available to authorized users. * Fabio Roldan [email protected] 1



Facultad de Ciencias, Departamento de Biología, Unidad de Saneamiento y Biotecnología Ambiental (USBA), Pontificia Universidad Javeriana, Carrera 7 No. 43‑82, Bogotá, DC, Colombia



Facultad de Ciencias, Departamento de Biología, Biología de Plantas y Sistemas Productivos, Pontificia Universidad Javeriana, Bogotá, Colombia

2

The compounds 2,4-dinitrotoluene (2,4-DNT), 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN) are nitrated xenobiotics found in the environment. TNT and PETN are explosives used in civilian and military activities (Stenui