Jaejung Lee

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.

The Actinobacterium Corynebacterium glutamicum, an Industrial Workhorse.

Starting as a glutamate producer, Corynebacterium glutamicum has played a variety of roles in the industrial production of amino acids, one of the most important areas of white biotechnology. From shortly after its genome information became available, C. glutamicum has been applied in various production processes for value-added chemicals, fuels, and polymers, as a key organism in industrial biotechnology alongside the surprising progress in systems biology and metabolic engineering. In addition, recent studies have suggested another potential for C. glutamicum as a synthetic biology platform chassis that could move the new era of industrial microbial biotechnology beyond the classical field. Here, we review the recent progress and perspectives in relation to C. glutamicum, which demonstrate it as one of the most promising and valuable workhorses in the field of industrial biotechnology.

Phylogenetic analysis of major molds inhabiting woods and their discoloration characteristics. Part 1. Genus Trichoderma

Abstract The genus Trichoderma Persoon is a cosmopolitan genus consisting of more than 104 species and is commonly found on wood surfaces as a mold where it affects the appearance. Little attention has been given to wood-colonizing Trichoderma species and few studies are dedicated for identification of Trichoderma at the level of species. In the present study, up to 142 isolates were obtained from various wood samples. One Gliocladium and ten Trichoderma species were identified by morphological and molecular analysis. T. atroviride (30.3%) was the most abundant species followed by T. citrinoviride (26.8%) and T. harzianum (23.9%). The ability of Trichoderma species to discolor wood was also examined on sapwood blocks made of the commercially important radiata pine (Pinus radiata). T. pleuroticola caused the greatest discoloration of the wood surface.

Diversity of Wood-Inhabiting Polyporoid and Corticioid Fungi in Odaesan National Park, Korea

Abstract Polyporoid and corticioid fungi are among the most important wood-decay fungi. Not only do they contribute to nutrient cycling by decomposing wood debris, but they are also valuable sources for natural products. Polyporoid and corticioid wood-inhabiting fungi were investigated in Odaesan National Park. Fruit bodies were collected and identified based on morphological and molecular analyses using 28S and internal transcribed spacer regions of DNA sequences. As a result, a total of 149 species, 69 genera, 22 families, and 11 orders were recognized. Half (74 species) of the species were polypores, and the other half (75 species) were corticioid fungi. Most of the species belonged to Polyporales (92 species) followed by Hymenochaetales (33 species) and Russulales (11 species). At the genus level, a high number of species was observed from Steccherinum, Hyphodontia, Phanerochaete, Postia, and Trametes. Concerning distribution, almost all the species could be found below 1,000 m, and only 20% of the species were observed from above 1,000 m. Stereum subtomentosum, Trametes versicolor, T. hirsuta, T. pubescens, Bjerkandera adusta, and Ganoderma applanatum had wide distribution areas. Deciduous wood was the preferred substrate for the collected species. Sixty-three species were new to this region, and 21 species were new to Korea, of which 17 species were described and illustrated.

Screening for xylanase and β-xylosidase production from wood-inhabiting Penicillium strains for potential use in biotechnological applications.

Abstract Experiments were performed to find potential sources for enzyme production for the pulp and paper industry and for biological ethanol production by screening the cellulase, xylanase and β-xylosidase activities of 36 species of Penicillium isolated from various wood materials in Korea. Rice straw powder (RiceP), birchwood xylan (BirchX), and beechwood xylan (BeechX) were supplied as individual carbon sources for the Penicillium species. All Penicillium species tested in this study showed little cellulase activity, but some species exhibited remarkably high xylanase and β-xylosidase activities, as determined by a filter paper assay. P. oxalicum showed the greatest xylanase activity on RiceP (158.70 U ml-1). On the other hand, P. brevicompactum produced the highest active β-xylosidase on BirchX (6.25 U ml-1).

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.

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.

Effect of Torrefaction Condition on The Chemical Composition and Fuel Characteristics of Larch wood

This study was conducted to investigate the potential of torrefied larch wood as a raw material of pellets. First of all, larch chip was torrefied at the temperatures of 230, 250 and 270℃ for 30, 50 and 70 min. Secondly, moisture content, moisture absorption, higher heating value and ash content of the torrefied chip were measured to examine the

Effects of The Torrefaction Process on The Fuel Characteristics Larix kaempferi C

ABSTRACT The aim of this study was to evaluate the fuel characteristics of thermally treated wood chips of the Larix kaempferi C. As torrefaction temperature was increased (200℃ to 300℃), the carbon content, calorific value, and mass loss of torrefied wood chips increased significantly. The torrefied wood chips were shown to have hydrophobic properties even when only treated by mild torrefaction. The energy required to grind torrefied wood chips was reduced by the torrefaction process. Different sizes of wood chips were used in this study; however, this produced almost no difference in the fuel characteristics of processed Larix kaempferi C, except in the distribution of ground wood particles. Similar results were observed when the wood chips were torrefied for different lengths of time (15 min to 60 min) at a constant temperature. Torrefaction was shown to have positive effects on the fuel characteristics of Larix kaempferi C, including improved energy density, storage, and grindability.Keywords : torrefaction,

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.