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Catechol Biodegradation by Pseudomonas Strain: A Critical Analysis

Md. Zeyaullah, Razi Ahmad, Asma Naseem, Badrul Islam, Hamad M. I. Hasan, Azza S. Abdelkafe, Faheem A. Benkhayal, Moshahid A. Rizvi and Arif Ali

Catechols are the most abundant organic pollutants of our environment. They are of major concern because of their persistence and toxicity and gave scientists a thinking to engineer/develop certain measures for its removal from the environment. Bacteria explore the environment for its nutritional requirement and degrade many of complex molecules available to them including the toxins and pollutants. Under biological process being the cheapest mode for removal of the catechols, the Pseudomonas putida has been found having the great potential to degrade them upto 500 mg/L. Such degradative bacteria, under normal circumstances, enzymatically convert xenobiotic, aromatic compounds to either catechol or protocatechuate. The most common catabolic pathway involves conversion of the parent molecules to chlorocatechols by the action of a monooxygenase or a dioxygenase. Many members of Pseudomonas carry plasmid that encodes enzymes capable of degrading aromatic and halogenated organic compounds. The degradation proceeds in two phases, first, an aromatic compound is prepared for ring cleavage by a variety of ring modification reactions. The second phase of degradation includes ring fission and subsequent reactions leading to the generation of tricarboxylic acid cycle intermediates. Two key enzymes involved in this 6-ketoadipate pathway are catechol 1, 2- dioxygenase and 3, 4-PCD