Chang-Young Hong

Levulinic acid production by two-step acid-catalyzed treatment of Quercus mongolica using dilute sulfuric acid

The objectives of this research were to produce a levulinic acid by two-step acid-catalyzed treatment of Quercus mongolica and to investigate the effect of treatment parameter (reaction temperature range: 100-230°C; sulfuric acid (SA) concentration range: 0-2%) on the levulinic acid yield. After 1st step acid-catalyzed treatment, most of the hemicellulosic C5 sugars (15.6gg/100gbiomass) were released into the liquid hydrolysate at the reaction temperature of 150°C in 1% SA; the solid fraction, which contained 53.5% of the C6 sugars, was resistant to further loss of C6 sugars. Subsequently, 2nd step acid-catalyzed treatment of the solid fractions was performed under more severe conditions. Finally, 16.5g/100g biomass of levulinic acid was produced at the reaction temperature of 200°C in 2% SA, corresponding to a higher conversion rate than during single-step treatment.

Whitening and antioxidant activities of bornyl acetate and nezukol fractionated from Cryptomeria japonica essential oil

The aim of this study was to investigate the whitening and antioxidant activities of essential oils from Cryptomeria japonica by determining their tyrosinase inhibition, 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging and superoxide dismutase (SOD)‐like activities.

Biodegradation of PCB congeners by white rot fungus, Ceriporia sp. ZLY-2010, and analysis of metabolites

Polychlorinated biphenyls (PCBs) are difficult to degrade due to poor solubility, toxicity, and thermal stability. In the present study, the feasibility of PCB congener biodegradation by Ceriporia sp. ZLY-2010 was evaluated. The biodegradation rates of four PCB congeners, 4,4′-dichlorobiphenyl, 2,3′,4′,5-tetrachlorobiphenyl, 2,2′,4,5,5′-pentachlorobiphenyl, and 2,2′,4,4′,5,5′-hexachlorobiphenyl were evaluated. The degradation rate of 4,4′-dichlorobiphenyl was 34.03% on incubation day 13, while that of 2,2′,4,4′,5,5′-hexachlorobiphenyl reached 40.05% on incubation day 17. Therefore, Ceriporia sp. ZLY-2010 was degrading the higher PCB congeners more efficiently. PCB congener degradation products were extracted using acetone and ethyl acetate. No 2,2′,4,5,5′-pentachlorobiphenyl metabolites were detected in Ceriporia sp. ZLY-2010 culture, whereas 2,2′,4,4′,5,5′-hexachlorobiphenyl appeared to degrade to benzoic acid. However, intermediates of 2,2′,4,4′,5,5′-hexachlorobiphenyl were not detected during degradation. Therefore, additional studies should be performed to explore the mechanisms of PCB degradation. Our results indicate that Ceriporia sp. ZLY-2010 is able to degrade highly chlorinated biphenyls and has potential for use in PCB biodegradation and bioremediation.

Whitening and Antioxidant Activities of Essential Oils from Cryptomeria japonica and Chamaecyparis obtusa

본 연구는 삼나무와 편백나무 정유의 tyrosinase 저해 활성과 DPPH (1,1-diphenyl-2- picryl-hydrazyl) radical 소거 활성, SOD (superoxide dismutase) 유사활성을 구명하여 정유의 미백 및 항산화 효능을 평가하였다. 본 연구를 통해 삼나무와 편백나무 정유의 미백 및 항산화 기능성 소재로 개발하기 위한 기초자료로 이용하고, 건조 중 발생하는 nVOCs의 부가적 가치를 확인하고자 하였다. 삼나무 및 편백나무 잎의 정유는 수증기 증류법으로 24시간 추출하였고, 목부는 고온 열처리기를 이용하여 80, 100, 120℃의 온도조건에서 열기 건조하여 건조 중 목부로부터 발생하는 부산물인 천연 휘발성 유기화합물 (nVOCs, Natural Volatile Organic Compounds)을 응축액의 형태로 추출하였다. 삼나무 잎의 정유가 편백나무 잎의 정유 보다 미백 및 항산화 활성에서 모두 높은 효과를 나타내었고 건조 시 발생한 nVOCs는 온도가 올라갈수록 미백 활성이 높아지는 것을 확인할 수 있었으며 항산화 활성은 120℃에서 발생한 삼나무 nVOCs에서만 나타났다.

dbHiMo: a web-based epigenomics platform for histone-modifying enzymes

Over the past two decades, epigenetics has evolved into a key concept for understanding regulation of gene expression. Among many epigenetic mechanisms, covalent modifications such as acetylation and methylation of lysine residues on core histones emerged as a major mechanism in epigenetic regulation. Here, we present the database for histone-modifying enzymes (dbHiMo; http://hme.riceblast.snu.ac.kr/) aimed at facilitating functional and comparative analysis of histone-modifying enzymes (HMEs). HMEs were identified by applying a search pipeline built upon profile hidden Markov model (HMM) to proteomes. The database incorporates 11 576 HMEs identified from 603 proteomes including 483 fungal, 32 plants and 51 metazoan species. The dbHiMo provides users with web-based personalized data browsing and analysis tools, supporting comparative and evolutionary genomics. With comprehensive data entries and associated web-based tools, our database will be a valuable resource for future epigenetics/epigenomics studies. Database URL: http://hme.riceblast.snu.ac.kr/

Involvement of extracellular and intracellular enzymes of Ceriporia sp. ZLY-2010 for biodegradation of polychlorinated biphenyls (PCBs)

This study examined the interrelation between the biodegradation of polychlorinated biphenyls (PCBs) by Ceriporia sp. ZLY-2010 and its fungal enzyme systems. The degradation rates of Aroclor 1254 and 1260 were 29.01% on day 5 and 36.80% on day 10, respectively. MnP (Manganese dependent peroxidase) and laccase activities showed the greatest increases in the samples containing Aroclors, indicating that extracellular enzymes of Ceriporia sp. ZLY-2010 were affected by the addition of Aroclors. However, the relationship between the biodegradation rate and extracellular enzymes might be obscured by the complexity of the biodegradation process. Cytochrome P450 monooxygenase was inhibited and the biodegradation rate of the Aroclor decreased by adding the inhibitor 1-aminobenzotriazole. Two-dimensional gel electrophoresis showed that intracellular enzymes play a significant role in the biodegradation of Aroclor. Complex extracellular and intracellular enzyme systems in Ceriporia sp. ZLY-2010 play an important role in degrading PCBs. Physiological changes of Ceriporia sp. ZLY-2010 caused by PCBs appeared to affect biodegradation of PCBs. However, it is necessary to further study the unidentified enzymes related to the biodegradation of Aroclor.

Antifungal activity of essential oil from Cryptomeria japonica against dermatophytic fungi

본 연구에서는 표재성 진균에 의한 피부질환 개선용 소재로의 개발을 위해 삼나무 정유의 표재성·알레르기성 진균, Trichophyton schoenleinii, Trichophyton tonsurans, Trichophyton mentagrophytes (interdigitale),Trichophyton rubrum, Epidermophyton floccosum, Aspergillus fumigatus에 대한 항진균 활성을 평가하여 삼나무 정유의 표재성 진균에 의한 피부질환 개선 소재로의 개발 가능성을 평가하고자 하였다. 항진균 활성 평가는 삼나무 정유의 MIC (Minimum Inhibitory Concentration) 측정과 TLC bioassay, 한천희석법을 통해 측정하였다. 또한 활성 성분의 주성분을 확인하기 위해 GC/MS 분석을 실시하였다. 삼나무 정유 crude oil의 MIC는 모든 균에서 500 ppm 이하의 농도 값을 나타냈으며, TLC bioassay를 통해 spot 1에서 항진균 효과를 확인하였다. 한천희석법을 통한 항진균 활성은 A. fumigatus를 제외한 모든 진균에 대해 삼나무 정유 crude oil의 경우,500 ppm 이상에서 100%의 활성을 나타냈고, 분획 D의 경우, 100 ppm에서도 100%의 활성을 나타냈다. TLCbioassay를 통해 항진균 활성을 나타낸 spot 1과 한천희석법을 통해 활성을 나타낸 분획 D를 GC/MS로 분석한결과 주성분은 elemol, γ-eudesmol, β-eudesmol이었다. 따라서 elemol, eudesmol 등은 표재성 진균에 의한 피부질환의 개선 소재로의 이용 가능성이 충분하다고 사료된다.

Biotransformation of (-)-α-pinene and geraniol to α-terpineol and p-menthane-3,8-diol by the white rot fungus, Polyporus brumalis

In this study, the monoterpenes, α-pinene and geraniol, were biotransformed to synthesize monoterpene alcohol compounds. Polyporus brumalis which is classified as a white rot fungus was used as a biocatalyst. Consequently α-terpineol was synthesized from α-pinene by P. brumalis mycelium, after three days. Moreover, another substrate, the acyclic monoterpenoids geraniol was transformed into the cyclic compound, p-menthane-3, 8-diol (PMD). The main metabolites, i.e., α-terpineol and PMD, are known to be bioactive monoterpene alcohol compounds. This study highlights the potential of fungal biocatalysts for monoterpene transformation.

Transcriptomic analysis of the white rot fungus Polyporus brumalis provides insight into sesquiterpene biosynthesis.

Object of this study was to identify genes and enzymes that are involved in sesquiterpene biosynthesis in the wood rotting fungus, Polyporus brumalis. Sesquiterpenes, β-eudesmane and β-eudesmol, were produced by the mycelium of P. brumalis cultured in modified medium. However, theses final products were not observed when the fungus was grown in potato dextrose medium. We used next generation sequencing (NGS) to identify differentially expressed genes (DEGs) related to terpene metabolism. This approach generated 25,000 unigenes and 127 metabolic pathways that were assigned to Kyoto Encyclopedia Genes Groups (KEGG). Further analysis of samples from modified medium indicated significant upregulation of 8 unigenes involved in the mevalonate (MVA) and methylerythritol phosphate (MEP) biosynthetic pathways. These pathways generate isopentenyl pyrophosphate (IPP) and farnesyl pyrophosphate (FPP), which are precursors for the synthesis of sesquiterpenes. Furthermore, genes encoding germacrene A synthase, which facilitate the cyclization of FPP, were only differentially expressed in mycelium from fungi grown in modified medium. Our data provide a resource for studying the molecular mechanisms underpinning sesquiterpene biosynthesis and terpene metabolism.

Degradation and polymerization of monolignols by Abortiporus biennis, and induction of its degradation with a reducing agent.

This study was carried out to better understand the characteristic modification mechanisms of monolignols by enzyme system of Abortiporus biennis and to induce the degradation of monolignols. Degradation and polymerization of monolignols were simultaneously induced by A. biennis. Whole cells of A. biennis degraded coniferyl alcohol to vanillin and coniferyl aldehyde, and degraded sinapyl alcohol to 2,6-dimethoxybenzene- 1,4-diol, with the production of dimers. The molecular weight of monolignols treated with A. biennis increased drastically. The activities of lignin degrading enzymes were monitored for 24 h to determine whether there was any correlation between monolignol biomodification and ligninolytic enzymes. We concluded that complex enzyme systems were involved in the degradation and polymerization of monolignols. To degrade monolignols, ascorbic acid was added to the culture medium as a reducing agent. In the presence of ascorbic acid, the molecular weight was less increased in the case of coniferyl alcohol, while that of sinapyl alcohol was similar to that of the control. Furthermore, the addition of ascorbic acid led to the production of various degraded compounds: syringaldehyde and acid compounds. Accordingly, these results demonstrated that ascorbic acid prevented the rapid polymerization of monolignols, thus stabilizing radicals generated by enzymes of A. biennis. Thereafter, A. biennis catalyzed the oxidation of stable monolignols. As a result, ascorbic acid facilitated predominantly monolignols degradation by A. biennis through the stabilization of radicals. These findings showed outstanding ability of A. biennis to modify the lignin compounds rapidly and usefully.