Analysis of naphthalene and phenanthrene degradation catabolic genes of phyllosphere bacterial strains, Alcaligenes faecalis and Alcaligenes sp. DN25

Abstract

The bacterial strains, Alcaligenes feacalis and Alcaligenes sp. DN25 which were isolated from the phyllosphere of four ornamental plant species, Ixora chinensis, Ervatamia divaricata, Hibiscus rosa-sinensis and Amaranthus cruentus in five highly polluted sites in Sri Lanka, showed the highest phenanthrene and naphthalene degradation ability. Transformation and plasmid curing results of them revealed, naphthalene and phenanthrene degradation ability of these bacterial strains were plasmid encoded character. The occurrence of naphthalene specific (nahR and nahU) genes and phenanthrene specific (phnAc and phnG) genes of these catabolic plasmids were analyzed by PCR using degenerate primers. According to the amplification results, plasmids of Alcaligenes faecalis and Alcaligenes sp. DN25 harbour nahR, nahU and phnG genes but, lack of phnAc gene. RFLP and sequence data of nahU and nahR amplicons revealed, both of these genes were homologous to these two bacterial strains. But, phnG gene of two phenanthrene and naphthalene degrading phyllosphere bacterial strains was coexistence as two distinct copies of alleles.