E. Omaka ,A Kalu
The environment faces tremendous challenges particularly oil pollution that pose significant threats to lives. Polycyclic aromatic hydrocarbons (PAHs), which are natural constituents of petroleum hydrocarbons, are ubiquitous organic compounds with known and suspected carcinogenic potentials. PAHs have the tendency of bioaccumulation and are recalcitrant in nature due to their biochemical stability. Effective bioremediation requires in-depth understanding of the pollutants, the microorganisms and the parameters involved. White rot fungi through the activities of their ligninolytic enzymes have shown abilities in degrading these PAHs. Fungal cultures were isolated by enrichment culture obtained from road-side soil in University of Hertfordshire College Lane Campus, Hatfield, United Kingdom and identified as Penicillium freii and Aspergillus niger. After identification, Penicillium freii and Aspergillus niger were cultured in malt extract broth adjusted to range of broth pH 5.5, 7.0 and 8.5, incubated on a rotary shaker and harvested after seven days. Laccase activity (μmol/ml/min) was determined by oxidation of ABTS. Laccase activity (μmol/ml/min) of Penicillium freii and Aspergillus niger was optimum at pH 5.5.