Biodegradation of monocyclic aromatic hydrocarbons by a newly isolated Pseudomonas strain

An aromatic hydrocarbon utilizing bacterium was isolated from Egyptian sewage treatment plant, it was identified as Pseudomonas sp. strain H12 and it showed 98% similarity to 16S rDNA genes of Pseudomonas meridiana and Pseudomonas antarctica. It has been never reported that these strains have any relation to hydrocarbon degradation. On the other hand, the isolated Pseudomonas sp. strain H12 has the ability to remove 85-90% of BTXHB mixture (benzene, toluene, xylene, hexyl-benzene and butyl-benzene) within 24 h. The results strongly suggest that the experimental bacterium has a TOL like-plasmid and carries tmoA, xylM and xylA involved in the expression of catechol-forming mono-oxygenases and xylEl which expresses a catechol dioxygenase. Thus, the catabolic pathway of an aromatic hydrocarbon by Pseudomonas sp. H12 is possibly initiated by only the activity of a mono-oxygenase system followed by a di-oxygenase catechol ring cleavage reaction. © 2008 Asian Network for Scientific Information.