Degradative pathways of polycyclic aromatic hydrocarbons (PAHs) by Phanerochaete chrysosporium under optimum conditions

Polycyclic aromatic hydrocarbons (PAHs) constitute one group of priority environmental contaminants which must be disposed. Phanerochaete chrysosporium is one of the white rot fungi (WRF) used in the present study to investigate different conditions affecting its ability to utilize PAHs as a sole carbon and energy sources. P. chrysosporium was grown under optimum conditions, and its degradation percentage and degradative pathways have been determined by HPLC and GC/MS. The results showed that the optimum condition for the growth of P. chrysosporium was five discs inoculum size at 25 degree C for 7 days incubation period on 100 mg/L of each PAHs in BSM supplemented with 2000 μM MnSO₄ with shaking. Four groups (I-IV) of optimum conditions were used to determine degradation percentage. The results cleared that the best PAHs in degradation was pyrene (Pyr.). P. chrysosporium degraded (100%) Pyr. under the four groups. P. chrysosporium degraded the six PAHs (Acen.; Anth.; Flu.; Naph.; Phen.; and Pyr.) efficiently. The intermediates resulted from degradation indicated that P. chrysosporium first oxidized the middle ring or hetero ring followed by ring fission. P. chrysosporium followed the phthalate route in its degradative pathway. The intermediates finally interred TCA cycle and give CO₂ and H₂O or short chain aliphatic polymerized to give long chains