Degradation of polycyclic aromatic hydrocarbons: Role of plasmids
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Date
2010-12-24
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Journal ISSN
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Publisher
Academic Journals : Scientific Research and Essays
Abstract
Polycyclic aromatic compounds are a group of highly recalcitrant organic pollutants. The initial steps in
the degradation of polycyclic aromatic hydrocarbon (PAHs) involve the dihydroxylation of the aromatic
ring, a step catalysed by dioxygenase enzymes. The degradation of many xenobiotic and hydrocarbon
compounds is known to be mediated by plasmid encoded enzymes. In this review, an insight is given
into the role of plasmid in degradation of PAHs, acquisition of degradative ability by these organisms
via horizontal transfer and clustering, resulting from tranposon-mediated recombination. There is
preponderance of information showing high level of plasmid involvement in the degradation of
naphthalene and other 2- and 3-ring PAHs. Information on higher molecular weight PAHs is however
scanty. Recent studies suggest possible involvement of plasmid in HMWPAH degradation than was
previously thought. Many plasmids involved in PAH-degradation are megaplasmids, of linear
configuration, encoding part or the whole genes for the complete pathways. In recent times, validation
of propositions on degradative gene acquisition by horizontal gene transfer (HGT) has been obtained
from field studies. HGT and transposition seems to be more chronologically linked and less fortuitously
directed than previously thought. Improvement on the methods used in isolation of degraders and
study of these is important, towards making a significant stride in elucidating plasmid involvement in
PAH degradation
Description
Staff Publication
Keywords
Plasmids,, degradation,, polycyclic aromatic hydrocarbon