Young Mok Heo

Investigation of Marine-Derived Fungal Diversity and Their Exploitable Biological Activities

Marine fungi are potential producers of bioactive compounds that may have pharmacological and medicinal applications. Fungi were cultured from marine brown algae and identified using multiple target genes to confirm phylogenetic placement. These target genes included the internal transcribed spacer (ITS), the nuclear large subunit (LSU), and the β-tubulin region. Various biological activities of marine-derived fungi were evaluated, including their antifungal, antioxidant and cellulolytic enzyme activities. As a result, a total of 50 fungi was isolated from the brown algae Sargassum sp. Among the 50 isolated fungi, Corollospora angusta was the dominant species in this study. The genus Arthrinium showed a relatively strong antifungal activity to all of the target plant pathogenic fungi. In particular, Arthrinium saccharicola KUC21221 showed high radical scavenging activity and the highest activities in terms of filter paper units (0.39 U/mL), endoglucanase activity (0.38 U/mL), and β-glucosidase activity (1.04 U/mL).

Optimization of Fungal Enzyme Production by Trichoderma harzianum KUC1716 through Surfactant-Induced Morphological Changes

Abstract The morphological optimization of Trichoderma harzianum was carried out using several surfactants to achieve increased cellulase production. Addition of the surfactants to the culture medium successfully modified the fungal morphology from an aggregated form to a dispersed form. Optimization of the fungal morphology increased cellulase activity up to 177%. The morphologically optimized conditions enhanced the accessibility of the fungus to substrates and thus promoted cellulase production.

Five New Records of Soil-Derived Trichoderma in Korea: T. albolutescens, T. asperelloides, T. orientale, T. spirale, and T. tomentosum

Abstract Despite the huge worldwide diversity of Trichoderma (Hypocreaceae, Ascomycota), only about 22 species have been reported in Korea. Thus, between 2013 and 2015, soil-derived Trichoderma spp. were isolated to reveal the diversity of Korean Trichoderma. Phylogenetic analysis of translation elongation factor 1 alpha gene was used for identification. Among the soil-derived Trichoderma, Trichoderma albolutescens, T. asperelloides, T. orientale, T. spirale, and T. tomentosum have not been previously reported in Korea. Thus, we report the five Trichoderma species as new in Korea with morphological descriptions and images.

Transcriptional analysis of genes encoding β-glucosidase of Schizophyllum commune KUC9397 under optimal conditions

The present study was conducted to determine the gene responsible for beta-glucosidase (BGL) production and to generate a full-length complementary DNA (cDNA) of one of the putative BGL genes, which showed a significant expression level when Schizophyllum commune KUC9397 was grown in optimized medium. The relative expression levels of seven genes encoding BGL of S. commune KUC9397 were determined with real-time quantitative reverse transcription PCR in cellulose-containing optimized medium (OM) compared to glucose-containing basal medium (BM). The most abundant transcript was bgl3a in OM. The transcript number of the bgl3a increased more than 57.60-fold when S. commune KUC9397 was grown on cellulose-containing OM compared to that on glucose-containing BM. The bgl3a was identified, and a deduced amino acid sequence of bgl3a shared homology (97%) with GH3 BGL of S. commune H4-8. This is the first report showing the transcription levels of genes encoding BGL and identification of full-length cDNA of glycoside hydrolase 3 (GH3) BGL from S. commune. Furthermore, this study is one of the steps for consolidated bioprocessing of lignocellulosic biomass to bioethanol.

Investigation of Filamentous Fungi Producing Safe, Functional Water-Soluble Pigments

Abstract The production of water-soluble pigments by fungal strains indigenous to South Korea was investigated to find those that are highly productive in submerged culture. Among 113 candidates, 34 strains that colored the inoculated potato dextrose agar medium were selected. They were cultured in potato dextrose broth and extracted with ethanol. The productivity, functionality (radical-scavenging activities), and color information (CIELAB values) of the pigment extracts were measured. Five species produced intense yellowish pigments, and two produced intense reddish pigments that ranked the highest in terms of absorbance units produced per day. The pigment extracts of Penicillium miczynskii, Sanghuangporus baumii, Trichoderma sp. 1, and Trichoderma afroharzianum exhibited high radical-scavenging activity. However, the S. baumii extract showed moderate toxicity in the acute toxicity test, which limits the industrial application of this pigment. In conclusion, P. miczynskii KUC1721, Trichoderma sp. 1 KUC1716, and T. afroharzianum KUC21213 were the best fungal candidates to be industrial producers of safe, functional water-soluble pigments.

Phylogenetic analysis of wood-inhabiting molds and assessment of soft-rot wood deterioration. Part 5. Genus Aureobasidium

Abstract The genus Aureobasidium is wellknown as a wood-staining mold and as a black yeast-like fungi, which produces mainly dark spores or pigmented hyphae within the wood cell lumens. Nevertheless, few studies are dedicated to wood-colonizing Aureobasidium species and little is known about the wood degradation patterns of this genus. In the present study, four Aureobasidium species, including Aureobasidium melanogenum, Aureobasidium leucospermi, Aureobasidium pullulans, and an unknown Aureobasidium sp., were isolated and identified based on phylogenetic analysis. A. melanogenum and A. leucospermi were observed for the first time in Korea. The degradation pattern of Douglas-fir by Aureobasidium was observed for the first time by scanning electron microscopy (SEM). All tested Aureobasidium species except an unknown Aureobasidium sp. revealed soft-rot Type ΙΙ (erosion) in sapwood pine.

Evaluation of Cellulolytic Enzyme Production by Indigenous Fungi in Korea

The aim of this study was to select various fungal strains indigenous to Korea that have the potential to produce cellulases, including filter paper activity (FPase), endo-β-1,4-glucanase (EG), and β-glucosidase (BGL). Among the 25 species of Ascomycetes and the 32 species of Basidiomycetes tested in this study, the Bjerkandera adusta KUC10565, Heterobasidion orientale KUC10556, Hyphoderma praetermissum KUC10609, and Trichoderma harzianum KUC1716 all exhibited remarkably high FPase activity. In addition, the T. harzianum KUC1716 showed high levels of EG and BGL activity. This strain has been selected for further study because of their enzymatic potential.