Bioremediation potential of wood-associated fungi in Rajawaka forest reserve, Balangoda

Abstract

Sri Lanka consists of a high diversity of fungal species, especially wood-associated fungi. These fungi play a vital ecological role in wood decomposition and have potential applications in environmental remediation due to their unique enzyme systems. Currently, the accumulation of polycyclic aromatic hydrocarbons (PAHs), mainly from vehicular emissions has become a significant environmental concern. Therefore, the present study aimed to identify the woodassociated macro and micro fungi in the Rajawaka forest reserve which is a lowland secondary forest located in the Balangoda area in the Rathnapura district, and to assess their ability to degrade specific PAHs, including phenanthrene, naphthalene, pyrene, and anthracene. Identification keys followed by morphological characteristics and image-based methods were used to identify the macrofungi. Microfungi were isolated following surface sterilization and culturing on potato dextrose agar (PDA) plates. Most frequently isolated fungal strains were subjected to plate assay to assess the fungal growth in PAHs by using 8 replicates. Control plates were prepared without inoculating fungi for each PAH-incorporated media. Spectrophotometric analysis was done to determine their PAH degradation abilities using 3 replicates. Controls were prepared without inoculating fungi. Obtained data were analyzed using ANOVA and Tukey’s pairwise comparison by using Minitab 17 statistical software. The macrofungi collected from the Rajawaka forest reserve were mainly in the phylum Basidiomycota; Ganoderma sp., Pycnoporus sp., Phellinus sp., Hexagonia sp., Trametes sp., Earliella sp., Schizophyllum sp., Lentinus sp., Calocera sp., Stereum sp., Microporus sp., and Pleurotus sp. Frequently isolated microfungi included Trichoderma sp. 1, Trichoderma sp. 5, Trichoderma sp. 6, Grey sterile sp., Mortierella sp. 2, Brown sporulating sp., Humicola sp., and Aspergillus sp. 1. Mortierella sp. 2 and Grey sterile sp. were significantly effective in degrading phenanthrene (42.51%, and 34.16% respectively) and naphthalene (41.27%, and 33.48% respectively), while Humicola sp. and Grey sterile sp. showed a high degradation capacity for anthracene (33.73%, and 23.72% respectively) and pyrene (30.62%, and 19.32% respectively). All the PAHs studied were efficiently degraded by Grey sterile sp. This investigation serves as a preliminary exploration of the wood-associated macro and microfungal diversity in the Rajawaka forest reserve, and their potential in remediating PAH pollutants. It also opens the avenue for future research in finding environmental solutions for bioremediation of PAH deposition in Sri Lanka.