Biodegradation of some polycyclic aromatic hydrocarbons by Aspergillus terreus

In our search for new fungal isolates capable of degrading polycyclic aromatic hydrocarbons (PAHs) in soil, twenty one fungal isolates were recovered from Orman Garden, Wadi Degla Protectorate and benzene station soils. All tested fungi exhibited lignin peroxidase and manganese peroxidase activities in solid as well as in liquid cultures. However, laccase was detected in low amounts by some of the tested fungal isolates. Accordingly, laccase was eliminated from further work. Aspergillus terreus was superior in ligninolytic enzyme production. Hence, it was chosen for the following studies. The statistical optimum temperatures for lignin peroxidase and manganese peroxidase production by A. terreus were 33.6 and 33.1°C, respectively. Meanwhile lignin peroxidase and manganese peroxidase yields were maximal at pH 4.1 and 5.8, respectively. Highest ligninolytic enzyme secretions were established on D-glucose and sodium nitrate. An experiment to study biodegradation of PAHs in soil was conducted. A. terreus was able to degrade 98.5% of naphthalene and 91% of anthracene in soil models.   Key words: Biodegradation, fungi, polycyclic aromatic hydrocarbons (PAHs) Ligninolytic enzymes, soil model