Biodegradation of mono-aromatic compounds by bacteria

Abstract

Aromatic hydrocarbons represent a group of ring structured hydrophobic and reduced compounds which are industrially significant and toxic in nature. Due to their presence in nature through anthropogenic and biological routes, micro-organisms have evolved/adapted to degrade these compounds. Aerobic bacteria initialize their degradation by incorporation of oxygen atoms by a group of enzymes 'oxygenases' which leads to the formation of cis-dihydrodiols. Subsequent formation of catechol intermediates followed by ortho- or meta-ring cleavage leads to intermediates which enter Kreb's cycle. The reaction sequences are repeated for additional rings in case of polycyclic aromatic compounds. A large array of metabolic diversity exists within these strains and several parameters regulate the efficient utilization of such compounds. Hence, an ideal microbial culture should have following features for its effective application in sustainable environmental development strategies: (i) ability to metabolize wide range of aromatic compounds even at high concentrations with novel pathways and enzymes, (ii) complete degradation of toxic pollutants without formation of toxic by-products, (iii) production of biosurfactants for solubilization and uptake of hydrophobic xenobiotic compounds and (iv) absence of carbon catabolite repression.