Isolation and characterization of naphthalene-degrading strains, Pseudomonas sp. CZ2 and CZ5

Bacterial strains CZ2 and CZ5, isolated from polycyclic aromatic hydrocarbons contaminated sludge in Wuhan, China, can utilize naphthalene as a sole source of carbon. They were both identified as Pseudomonas based on Gram staining and 16S rRNA gene sequence analysis. Pseudomonas sp. CZ2 and CZ5 can remove 61.8 and 64.3% of naphthalene with an initial concentration of 1 g/L in 48 h, respectively. Addition of glucose as second carbon source, had different effects on strains CZ2 and CZ5 growth. Both strains harbored the same naphthalene dioxygenase genes, and the salicylate route was likely the metabolic pathway for naphthalene degradation. PCR analysis of catechol dioxygenase genes showed both catechol 1,2-dioxygenase and catechol 2,3-dioxygenase in strain CZ2, and only catechol 2,3-dioxygenase in strain CZ5. Therefore, strains CZ2 and CZ5 have different metabolic pathways for cleavage of the aromatic ring. Such strainsmay be useful for bioremediation of PAH-contaminated sites.   Key words: Pseudomonas sp., naphthalene, biodegradation, dioxygenase, metabolic pathways.