Response of a Newly Identified Trichoderma Harzianum KY488466 to Crude Oil Pollution and Its Expression of Peroxidase Genes

Many fungi were able to degrade/mineralize hydrocarbons in polluted soils after a long-term exposure, this they do mostly through the secretions of different enzymes such as catalases, peroxidases, laccases, and so on. This study therefore investigated the response and tolerance of a newly identified Trichoderma harzianum to crude oil pollution and its expression of peroxidase enzymes (LiP and MnP). Fifty fungal strains were isolated from rhizosphere of grasses growing in a crude oil polluted site. The most frequently isolated strain (asemoJ) was hypothesized to be the best strain that could tolerate the pollution and it was further characterized using morphological characters (such as mycelial growth pattern, spore color, conidiophore, conidial production, serration of the colony, vesicular shape) and molecularly through the amplification of 18s (1609-1627) and 28s (287-266) rRNA regions using ITS1/ITS4. The selected fungus was also subjected to in-vitro crude oil tolerance test at concentrations of 5, 10, 15, 20 and 25% crude oil, while 0% served as control. In addition, lignin peroxidase (lig1-6) and manganese peroxidase (mnp) genes were detected and expressed in this strain using RT-PCR technique, and the activities of enzymes produced by the strain were also studied in aliquots (U/ml). The selected strain had highest incidence (80%) in crude oil polluted site and it was registered in NCBI as Trichoderma harzianum asemoJ with accretion number KY488466. The strain KY488466 tolerated crude oil concentrations up to 25 % but its Dose Inhibition Response Percentage (DIRP) decreased as the oil concentration increase, it increased from 41.67 % to 46.25 % at 10 to 15 % respectively but then decreased to 91.67 and 95.41 at 20 and 25 % crude oil respectively. Tested peroxidase genes were all present in the fungus and they were all expressed (900-1000 bp), lig2, lig4 and mnp genes were however more induced and expressed, compared to lig6 which was less expressed. Interestingly, the fungus produced up till 90±0.87 U/ml lignin peroxidase and 120±1.23 U/mil manganese peroxidase enzymes in aliquots. These results suggest that KY488466 could be exploited for bioremediation of oil-spilled soil and some other biotechnological applications.