Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by fungal enzymes: A review
Tayssir Kadri , Tarek Rouissi , Satinder Kaur Brar , Maximiliano Cledon , Saurabhjyoti Sarma , Mausam Verma
DOI:10.1016/j.jes.2016.08.023
Received March 29, 2016,Revised August 22, 2016, Accepted August 23, 2016, Available online October 03, 2016
Volume 29,2017,Pages 52-74
Polycyclic aromatic hydrocarbons (PAHs) are a large group of chemicals. They represent an
important concern due to their widespread distribution in the environment, their
resistance to biodegradation, their potential to bioaccumulate and their harmful effects.
Several pilot treatments have been implemented to prevent economic consequences and
deterioration of soil and water quality. As a promising option, fungal enzymes are regarded
as a powerful choice for degradation of PAHs. Phanerochaete chrysosporium, Pleurotus ostreatus
and Bjerkandera adusta are most commonly used for the degradation of such compounds
due to their production of ligninolytic enzymes such as lignin peroxidase, manganese
peroxidase and laccase. The rate of biodegradation depends on many culture conditions,
such as temperature, oxygen, accessibility of nutrients and agitated or shallow culture.
Moreover, the addition of biosurfactants can strongly modify the enzyme activity. The removal of PAHs is dependent on the ionization potential. The study of the kinetics is not completely comprehended, and it becomes morem hallenging when fungi are applied for bioremediation. Degradation studies in soil are much more complicated than liquid cultures because of the heterogeneity of soil, thus, many factors should be considered when studying soil bioremediation, such as desorption and bioavailability of PAHs. Different degradation pathways can be suggested. The peroxidases are heme-containing enzymes having common catalytic cycles. One molecule of hydrogen peroxide oxidizes the resting enzyme withdrawing two electrons. Subsequently, the peroxidase is reduced back in two steps of one electron oxidation. Laccases are copper-containing oxidases. They reduce molecular oxygen to water and oxidize phenolic compounds.
