Joo Hyun Hong

Biotechnological procedures to select white rot fungi for the degradation of PAHs

White rot fungi are essential in forest ecology and are deeply involved in wood decomposition and the biodegradation of various xenobiotics. The fungal ligninolytic enzymes involved in these processes have recently become the focus of much attention for their possible biotechnological applications. Successful bioremediation requires the selection of species with desirable characteristics. In this study, 150 taxonomically and physiologically diverse white rot fungi, including 55 species, were investigated for their performance in a variety of biotechnological procedures, such as dye decolorization, gallic acid reaction, ligninolytic enzymes, and tolerance to four PAHs, phenanthrene, anthracene, fluoranthene, and pyrene. Among these fungi, six isolates showed the highest (>90%) tolerance to both individual PAH and mixed PAHs. And six isolates oxidized gallic acid with dark brown color and they rapidly decolorized RBBR within ten days. These fungi revealed various profiles when evaluated for their biotechnological performance to compare the capability of degradation of PAHs between two groups selected. As the results demonstrated the six best species selected from gallic acid more greatly degraded four PAHs than the other isolates selected via tolerance test. It provided that gallic acid reaction test can be performed to rank the fungi by their ability to degrade the PAHs. Most of all, Peniophora incarnata KUC8836 and Phlebia brevispora KUC9033 significantly degraded the four PAHs and can be considered prime candidates for the degradation of xenobiotic compounds in environmental settings.

Antibacterial and Water Purification Activities of Self-Assembled Honeycomb Structure of Aerosol Deposited Titania Film

A simple and rapid room-temperature aerosol deposition method was used to fabricate TiO(2) films for photokilling/photdegradation applications. TiO(2) particles were accelerated to supersonic speeds and fractured upon impacting a glass substrate to form a functional thin film, a process known as aerosol deposition. After deposition, the films were annealed at various temperatures, and their photokilling/photodegradation performances following ultraviolet (UV) exposure were evaluated by counting the number of surviving bacterial colonies, and by a methylene blue decolorization test. The photocatalytic performances of all TiO(2) films were obtained under weak UV exposure (0.6 mW/cm(2)). The film density, crystalline phase, and surface roughness (morphology) were measured by scanning electron microscopy, X-ray diffraction, UV-visible spectroscopy, and atomic force microscopy. The unique, self-assembled honeycomb structure of the aerosol deposited films contributed to the increase in surface area because of extreme roughness, which enhances the photokilling and photodegradation performance. Nonannealed films yielded the best photocatalytic performance due to their small crystalline sizes and large surface areas due to increased surface roughness.

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).

Comparison of the Diversity of Basidiomycetes from Dead Wood of the Manchurian fir (Abies holophylla) as Evaluated by Fruiting Body Collection, Mycelial Isolation, and 454 Sequencing

In this study, three different methods (fruiting body collection, mycelial isolation, and 454 sequencing) were implemented to determine the diversity of wood-inhabiting basidiomycetes from dead Manchurian fir (Abies holophylla). The three methods recovered similar species richness (26 species from fruiting bodies, 32 species from mycelia, and 32 species from 454 sequencing), but Fisher’s alpha, Shannon-Wiener, Simpson’s diversity indices of fungal communities indicated fruiting body collection and mycelial isolation displayed higher diversity compared with 454 sequencing. In total, 75 wood-inhabiting basidiomycetes were detected. The most frequently observed species were Heterobasidion orientale (fruiting body collection), Bjerkandera adusta (mycelial isolation), and Trichaptum fusco-violaceum (454 sequencing). Only two species, Hymenochaete yasudae and Hypochnicium karstenii, were detected by all three methods. This result indicated that Manchurian fir harbors a diverse basidiomycetous fungal community and for complete estimation of fungal diversity, multiple methods should be used. Further studies are required to understand their ecology in the context of forest ecosystems.

6-Pentyl-α-pyrone as an anti-sapstain compound produced by Trichoderma gamsii KUC1747 inhibits the germination of ophiostomatoid fungi

Abstract The capability of Trichoderma gamsii to biologically control sapstain fungi has been investigated. Six ophiostomatoids, including Ophiostoma floccosum, O. piceae, O. piliferum, O. ips, Grosmannia koreana, and G. piceaperda, were inhibited by the extracts of T. gamsii. Of the various cultivation periods, 7 days of T. gamsii cultivation produced antifungal compounds most efficiently. The crude extracts of T. gamsii inhibited O. ips, G. koreana, and G. piceaperda by over 99%. The crude extracts of T. gamsii were isolated, and the compounds were purified by thin layer chromatography (TLC), open column chromatography, ultra-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) and NMR spectroscopy. The active fractions were separated based on the degree of T. gamsii antifungal activity. The compound 6-pentyl-α-pyrone (6PAP) was evaluated as a biological control agent for sapstain fungi.

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.

Wood decay fungi in South Korea: Polypores from seoul

Abstract In Seoul, a majority of plant communities have undergone significant changes over the last few decades; however, how wood decay fungi have responded and adapted to the changes in vegetation remains unknown. Through an ongoing investigation of Korean indigenous fungi, ca. 300 specimens with poroid basidiocarp were collected in Seoul during 2008~2012. Morphological examination and molecular analysis using the internal transcribed spacer and nuclear large subunit ribosomal DNA region sequences helped identify 38 species belonging to 28 genera, 10 families, and 5 orders in this area. Among them, three polypores, Abundisporus pubertatis, Coriolopsis strumosa, and Perenniporia maackiae were found to be new to South Korea.

The antagonistic properties of Trichoderma spp. inhabiting woods for potential biological control of wood-damaging fungi

Abstract The antagonistic potential of Trichoderma spp. for biological control of wood-damaging fungi was investigated in the present paper. In vitro assays to investigate antifungal characteristics of Trichoderma spp. were conducted with various wood-damaging fungi. Exo-chitinase activity of the isolates was also measured. Three typical wood decayers and three sap-stainers served as target fungi. The antagonistic abilities of each Trichoderma species differed markedly according to the target fungus. The growth inhibition rates shown by the non-volatile metabolites against the wood decayers reached 100% for Trichoderma harzianum KUC1459. The antibiotics produced by Trichoderma dorotheae KUC5027, a recently reported species of Trichoderma, revealed strong antagonistic effects against sap-stainers. Trichoderma gamsii KUC1747 effectively inhibited the growth of all wood-damaging fungi in dual culture tests. The exo-chitinases of Trichoderma longibrachiatum KUC1540, Trichoderma aureoviride KUC1335, and T. harzianum KUC1459 showed significantly high activity.

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.

Phylogenetic analysis of the genus Fusarium and their antifungal activity against wood-decay and sapstain fungi

Abstract Microorganism-based biological protections are alternatives to chemical treatments. Worldwide, Fusarium species are important plant pathogens, and their mycotoxins are antimicrobial. In this study, 18 Fusarium strains isolated in Korea have been investigated. Nine Fusarium species, including two unknown species, were identified based on their genotypic characteristics. Among the identified species, Fusarium armeniacum and Fusarium commune were observed for the first time in Korea. The antifungal activity of Fusarium crude extracts was assessed by growth inhibition against two wood-decay fungi and three sapstain fungi. Most Fusarium strain extracts revealed strong antifungal activity against wood-decay fungi. Strains of the unknown Fusarium sp. 2, which was found in wood samples, showed strong antifungal activity against all wood-decay and sapstain fungi tested in this study.