Biodegradation of polycyclic aromatic hydrocarbons commonly found in coal slurry using white rot fungi isolated from east kalimantan

Abstract

Fifty specimens of white-rot fungi were identified and placed into 6 families and 30 species. Two new records of resupinate fungi (Basidiomycota) were discovered and reported for Indonesia: Ceriporia inflata and Ceriporia lacerata. Furthermore, a four-step screening protocol to select WRF has been conducted. These stepwise protocols have selected Trametes polyzona PBURU 12 based on its superior performance among the 30 isolates tested in this experiment with laccase as the major LMEs produced. Plackett-Burman’s design was used for screening multiple factors at a time. The result suggested that the highest positive effects influencing laccase production by PBURU 12 were glucose, peptone, CuSO4 and pH. Furthermore, the response surface methodology (RSM) showed that the optimized medium induced a nearly 3-folds increase in laccase activity compared to the basal medium. The optimum pH and stability were shown at pH 4.5 and 5.0, respectively. PBURU 12 acted in the broad temperature range of 20-70°C and stable at 20-40°C for 60 minutes. Cu2+ was showed a stimulatory effect on laccase activity, while Fe2+ and NaN3 were found to be potent inhibitors. Degradation of PAHs using crude laccase (1 U/ml) of PBURU 12 was able to degrade PAHs up to 50% within 24 hours. PAHs degradation were increased to 1-fold when ABTS was added, and up to 2-fold when laccase concentration was increased to 10 U/ml. The crude laccase was capable to degrade the PAHs mixture up to 70%. The genotoxicity experiment using Allium cepa L. revealed that the laccase-treated PAHs were less toxic compared to untreated. While the results of the AMES test with Salmonella typhimurium revealed that strain TA98 and TA100 showed different mutagenic activity toward untreated and treated-PAHs.