A double mutant of Pseudomonas putida JLR11 deficient in the synthesis of the nitroreductase PnrA and assimilatory nitrite reductase NasB is impaired for growth on 2,4,6-trinitrotoluene (TNT).

Pseudomonas putida JLR11 can grow on 2,4,6-trinitrotoluene (TNT) as the sole nitrogen source. We created nasB (nitrite reductase), pnrA (nitroaromatic reductase) and pnrA nasB mutants and tested their growth with TNT as the sole N source. The nasB and pnrA mutants grew at a reduced rate on TNT, whereas the double nasB pnrA mutant did not. This suggests that P. putida JLR11 carries out multiple enzymatic attacks on TNT-releasing nitrite and/or ammonium. The PnrA nitroreductase plays a key role in the reduction of TNT to 2,6-dinitro-4-hydroxylaminotoluene and the subsequent release of ammonium for growth.