Abstract
145 fungal isolates were obtained from three sampling sites situated within the Nam River basin, located in the southern region of South Korea. Through ITS sequence analysis, the fungal isolates were identified to comprise 55 species of ascomycetes and 11 species of basidiomycetes. The 55 species of ascomycetes exclusively belong to the phylum Pezizomycotina, comprising 33 species of Dothideomycetes, 6 species of Eurotiomycetes, and 16 species of Sordariomycetes. Regarding their plant pathogenicity, an investigation into the fungi's ability to penetrate solid media revealed Nigrospora chinensis as displaying the highest growth, followed by Pseudopestalotiopsis theae, various Curvularia species, Diaporthe species, and Alternaria alternata. Further research associating this penetration ability with fungal pathogenicity is deemed necessary. Among the 10 fungal species exhibiting penetration abilities, an examination of their capability to degrade biological polymers revealed that two strains of D. phaseolorum displayed exceptional polymer degradation. These strains exhibited remarkable abilities in decomposing malachite green and crystal violet, both recalcitrant dyes. This study underscores the potential utilization of fungal diversity in freshwater environments as a foundational approach to address freshwater pollution issues.