Cloning and expression of Vitreoscilla hemoglobin gene in Burkholderia sp strain DNT for enhancement of 2,4-dinitrotoluene degradation

The gene (vgb) encoding the hemoglobin (VHb) of Vitreoscilla sp. was cloned into a broad host range vector and stably transformed into Burkholderia (f ormerly Pseudomonas) sp. strain DNT, which is able to degrade and metaboliz e 2,4-dinitrotoluene (DNT). Vgb was stably maintained and expressed in func tional form in this recombinant strain (YV1). When growth of YV1, in both t ryptic soy broth and minimal salts broth containing DNT and yeast extract, was compared with that of the untransformed strain, YV1 grew significantly better on a cell mass basis (A(600)) and reached slightly higher maximum vi able cell numbers. YV1 also had roughly twice the respiration as strain DNT on a cell mass basis, and in DNT-containing medium, YV1 degraded DNT faste r than the untransformed strain. YV1 cells pregrown in medium containing DN T plus succinate showed the fastest degradation: 100% of the initial 200 pp m DNT was removed from the medium within 3 days.