Abstract

Aromatic compounds (biogenic and anthropogenic) are abundant in the biosphere. Some of them are well-known environmental pollutants. Although the aromatic nucleus is relatively recalcitrant, microorganisms have developed various catabolic routes that enable complete biodegradation of aromatic compounds. The adopted degradation pathways depend on the availability of oxygen. Under oxic conditions, microorganisms utilize oxygen as a cosubstrate to activate and cleave the aromatic ring. In contrast, under anoxic conditions, the aromatic compounds are transformed to coenzyme A (CoA) thioesters followed by energy-consuming reduction of the ring. Eventually, the dearomatized ring is opened via a hydrolytic mechanism. Recently, novel catabolic pathways for the aerobic degradation of aromatic compounds were elucidated that differ significantly from the established catabolic routes. The new pathways were investigated in detail for the aerobic bacterial degradation of benzoate and phenylacetate. In both cases, the pathway is initiated by transforming the substrate to a CoA thioester and all the intermediates are bound by CoA. The subsequent reactions involve epoxidation of the aromatic ring followed by hydrolytic ring cleavage. Here we discuss the novel pathways, with a particular focus on their unique features and occurrence as well as ecological significance.

Links

PMC Free PDF

Publisher Full Text

Authors

Ismail W, Gescher J

Institution

Biotechnology Program, College of Graduate Studies, Arabian Gulf University, Manama, Kingdom of Bahrain. waelame@agu.edu.bh

Source

Applied and environmental microbiology 78:15 2012 Aug pg 5043-51

MeSH

Biodegradation, Environmental
Coenzyme A
Epoxy Compounds
Esters
Hydrocarbons, Aromatic
Hydrolysis
Metabolic Networks and Pathways
Molecular Structure
Oxygen

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Review

Language

eng

PubMed ID

22582071