Rhizoremediation of Dioxin-like Compounds by a Recombinant Rhizobium tropici Strain Expressing Carbazole 1,9a-Dioxygenase Constitutively

Abstract

  A recombinant Rhizobium strain, PBK3-IS, that constitutively expressed the oxygenase component of carbazole 1,9a-dioxygenase from Sphingomonas sp. strain KA1, was constructed. In the water-cultured siratro rhizospheres inoculated with strain PBK3-IS, 48% of the dibenzofuran was removed within 3 days (initial substrate, 25 μg). Similar results were obtained in soil-cultured siratro rhizospheres using sterile vermiculite. When non-sterile field soils were used instead of sterile vermiculite, the inoculated recombinant strain could grow on the siratro root in all soils tested, except for wet paddy field.