• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.04a
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• pp.81-91
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• 2011

Current fuel ethanol research and development deals with process engineering trends for improving biotechnological production of ethanol. Recently, a large amount of studies regarding the utilization of lignocellulosic biomass as a good feedstock for producing fuel ethanol is being carried out worldwide. The plant biomass is mainly composed of cellulose, hemicellulose and lignin. The main challenge in the conversion of biomass into ethanol is the complex, rigid and harsh structures which require efficient process and cost effective to break down. The isolation of microorganisms is one of the means for obtaining enzymes with properties suitable for industrial applications. For these reasons, crude cultures containing cellulosic biomass degrading microorganisms were isolated from rice field soil, cow farm soil and rotten rice straw from cow farm. Carboxymethyl cellulose (CMC), xylan and Avicel (microcrystalline cellulose) degradation zone of clearance on agar platefrom rice field soil resulted approximately at 25 mm, 24 mm and 22 mm respectively. As for cow farm soil, CMC, xylan and Avicel degradation clearancezone on agar plate resulted around at 24mm, 23mm and 21 mm respectively. Rotten rice straw from cow farm also resulted for CMC, xylan and Avicel degradation zone almost at 24 mm, 23 mm and 22 mm respectively. The objective of this study is to isolatebiomass degrading microbial strains having good efficiency in cellulose hydrolysis and observed the effects of different substrates (CMC, xylan and Avicel) on the production of cellulase enzymes (endo-glucanase, exo-glucanase, cellobiase, xylanase and avicelase) for producing low cost biofuel from cellulosic materials.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.1952-1960
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• 2017

Recently, soybean isoflavone aglycones (i.e., daidzein and genistein) and ${\gamma}-aminobutyric$ acid (GABA) have begun to receive considerable consumer attention owing to their potential as nutraceuticals. To produce these ingredients, multiple microorganisms and their enzymes are commonly used for catalysis in the nutraceutical industry. In this work, we introduce a novel fermentation process that uses whole-cell biocatalysis to accelerate GABA and isoflavone aglycone production in doenjang (a traditional Korean soybean paste). Microbial enzymes transform soybean isoflavone glycosides (i.e., daidzin and genistin) and monosodium glutamate into soybean isoflavone aglycones and GABA. Lactobacillus brevis GABA 100 and Aspergillus oryzae KACC 40250 significantly reduced the production time with the aid of a protease. The resulting levels of GABA and daidzein were higher, and genistein production resembled the levels in traditional doenjang fermented for over a year. Concentrations of GABA, daidzein, and genistein were measured as 7,162, 60, and $59{\mu}g/g$, respectively on the seventh day of fermentation. Our results demonstrate that the administration of whole-cell L. brevis GABA 100 and A. oryzae KACC 40250 paired with a protease treatment is an effective method to accelerate GABA, daidzein, and genistein production in doenjang.

• The Plant Pathology Journal
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• v.31 no.2
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• pp.165-175
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• 2015

Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous plant species. Anthracnose control with fungicides has both human health and environmental safety implications. Despite increasing public concerns, fungicide use will continue in the absence of viable alternatives. There have been relatively less efforts to search antagonistic bacteria from mudflats harboring microbial diversity. A total of 420 bacterial strains were isolated from mudflats near the western sea of South Korea. Five bacterial strains, LB01, LB14, HM03, HM17, and LB15, were characterized as having antifungal properties in the presence of C. acutatum and C. gloeosporioides. The three Bacillus atrophaeus strains, LB14, HM03, and HM17, produced large quantities of chitinase and protease enzymes, whereas the B. amyloliquefaciens strain LB01 produced protease and cellulase enzymes. Two important antagonistic traits, siderophore production and solubilization of insoluble phosphate, were observed in the three B. atrophaeus strains. Analyses of disease suppression revealed that LB14 was most effective for suppressing the incidence of anthracnose symptoms on pepper fruits. LB14 produced antagonistic compounds and suppressed conidial germination of C. acutatum and C. gloeosporioides. The results from the present study will provide a basis for developing a reliable alternative to fungicides for anthracnose control.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.346-356
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• 2011

BACKGROUND: Chemical fungicides not only may pollute the ecosystem but also can be environmentally hazardous, as the chemicals accumulate in soil. Biological control is a frequently-used environment-friendly alternative to chemical pesticides in phytopathogen management. However, the use of microbial products as fungicides has limitations. This study isolated and characterized a three-antifungal-enzyme (chitinase, cellulase, and ${\beta}$-1,3-glucanase)-producing bacterium, and examined the conditions required to optimize the production of the antifungal enzymes. METHOD AND RESULTS: The antifungal enzymes chitinase, cellulase, and ${\beta}$-1,3-glucanase were produced by bacteria isolated from an sawmill in Korea. Based on the 16S ribosomal DNA sequence analysis, the bacterial strain AM50 was identical to Streptomyces sp. And their antifungal activity was optimized when Streptomyces sp. AM50 was grown aerobically in a medium composed of 0.4% chitin, 0.4% starch, 0.2% ammonium sulfate, 0.11% $Na_2HPO_4$, 0.07% $KH_2PO_4$, 0.0001% $MgSO_4$, and 0.0001% $MnSO_4$ at $30^{\circ}C$. A culture broth of Streptomyces sp. AM50 showed antifungal activity towards the hyphae of plant pathogenic fungi, including hyphae swelling and lysis in P. capsici, factors that may contribute to its suppression of plant pathogenic fungi. CONCLUSION(S): This study demonstrated the multiantifungal enzyme production by Streptomyces sp. AM50 for the biological control of major plant pathogens. Further studies will investigate the synergistic effect, to the growth regulations by biogenic amines and antifungal enzyme gene promoter.

• Polymer(Korea)
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• v.29 no.1
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• pp.54-58
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• 2005

The hydrolytic behavior of microbial poly[(R)-3-hydroxybutyrate]](P(3HB)) has been studied by using two model systems, Langmuir monolayer and solution-grown single crystals (SCs), for elucidating the mechanism for both alkaline and enzymatic degradations. An initial degradation of SCs of P(3HB) leads to breakup lamellae parallel to their short axis (b-axis). Similarly, ridge formation on the lamellar surface appears along the b-axis at lower quenching temperature than melting temperature. Both results support that the lamellar crystals contain less-ordered and more thermally sensitive regions along the b-axis. Although the enzymatic hydrolysis of P(3HB) monolayers was similar to its alkaline one, the enzymatic degradation of P(3HB) monolayers occurred at higher constant surface pressure than the alkaline degradation. This behavior might be attributed to the size of enzymes which is much larger than that of alkaline ions; that is, the enzymes need larger contact area with monolayers to be activated.

• Microbiology and Biotechnology Letters
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• v.46 no.4
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• pp.390-394
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• 2018

For the coexpression of endoxylanase and endoglucanase genes in yeast Saccharomyces cerevisiae, the genes were separately inserted downstream of the yeast ADH1 promoters, resulting the plasmid pAGX3 (9.83 kb). In the batch culture on YPD medium of the yeast transformant, S. cerevisiae SEY2102/pAGX3, the total activities of the enzymes reached about 7.91 units/ml for endoxylanase and 0.43 units/ml for endoglucanase. In the fed-batch culture with intermittent feeding of yeast extract and glucose, the total activities of 24.9 units/ml for endoxylanase and 0.84 units/ml for endoglucanase were produced which were about 3.1-fold and 2.0-fold increased levels, respectively, compared to those of the batch culture. Most of endoxylanase and endoglucanase activities were found in the extracellular media. This recombinant yeast could be useful for the development of simultaneous saccharification bioprocess of the cellulose and xylan mixture.

• Journal of Applied Biological Chemistry
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• v.64 no.1
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• pp.97-102
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• 2021

In this study, enzymes were screened for hydrolysis of defatted perilla seed residue (DPSR) and optimal conditions for enzymatic treatment were determined to produce the hydrolysate of DPSR. Also its antioxidant activity and utilization as a culture medium were examined. The combined treatment of Alcalase and Ceremix is most effective for solubilization of protein and carbohydrate in DPSR. The optimal dosage, pH, and reaction time for enzymatic treatment were found to be 2.0% (w/w), 7.0, and 2 h, respectively. Treatment with optimal conditions of enzymes dramatically increased reducing sugar, soluble protein, and total phenolic content. The hydrolysate of DPSR possessed better scavenging activity against cation and free radicals than enzyme-untreated extract. When Leuconostoc mesenteroides 310-12 was cultured in the hydrolysate of DPSR, cell population rapidly increased compared to enzyme-untreated extract, and titratable acidity increased in proportion to the bacterial growth. In conclusion, these results imply that the hydrolysate of DPSR could be utilized as a bacteria culture medium as well as a physiologically active material with antioxidant activity.

• Korean Journal of Environment and Ecology
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• v.24 no.4
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• pp.426-435
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• 2010

The present study attempts to compare the soil chemical characteristics and biological activities (i.e. microbial biomass and soil enzyme activities), and litter decomposition rate of Arundinella hirta and Miscanthus sinensis var. purpurascens) collected from serpentine and non-serpentine sites by litter bag techniques at serpentine and non-serpentine field experiment sites over a 9-month period. The serpentine soil showed higher pH and soil alkaliphosphatase activity, and lower soil dehydrogenase and urease activities than the non-serpentine soil. Microbial biomass-N at the serpentine soil was larger than the non-serpentine soil, although the microbial biomass-C and microbial biomass-N represented no significant difference between serpentine and non-serpentine soil. These results suggest that the larger microbial biomass-N caused the lower C/N in serpentine soil. At the end of the experiment, the litter samples of A. hirta and M. sinensis collected from serpentine soil revealed a 39.8% and 38.5% mass loss, and the litter sample from non-serpentine soil also showed a 41.1% and 41.7% mass loss at the serpentine site. On the other hand, at the non-serpentine site, 42.2%, 37.4%, and 46.8%, 44.8% were respectively shown. These results demonstrate that the litter decomposition rate is more intensely affected by the heavy metal content of leaf litter than soil contamination. Moreover, the litter collected from the serpentine soil had a lower C/N, whereas the litter decomposition rate was slower than the litter from the non-serpentine soil, because the heavy metal inhibition activities on the litter decomposition process were more conspicuous than the effect of litter qualities such as C/N ratio or lignin/N. The nutrient element content in the decomposing litter was gradually leached out, but heavy metals and Mg were accumulated in the decaying litter. This phenomenon was conspicuous at the serpentine site during the process of decomposition.

• Korean Journal of Microbiology
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• v.11 no.4
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• pp.157-166
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• 1973

Fermented feed using rice, barley, wheat, and defatted rice brans as the raw materials were prepared by 3 species of wild yeasts which were selected among 35 strains of yeasts isolated, and their analytical values were examined. The results were as follows : 1. The three yeasts were identified as H.amomala var. anomala (No.225), Candida utilis (No.400), and Irpex-cellulase(consors) (no.403-A). 2. The optimum pH, and sugar concentration of these yeasts in liquid culture were pH 5.0 and Bllg. 10.deg. each. The optimum temperature was 30.deg.C for No.225 and No.403-A, 25.deg.C for No.400. The No.225 and No.403-A grow at higher temperature than 37.deg.C and 40.deg.C each. 3. The No.225 yeast had a large vegetative cell and strong sugar fermentability. The No.225 and 403-A could assimilate cellobiose, xylose, $KNO_2$ and $KNO_3$. These properties were fit for bran fermentation. 4. The No.403-A microorganism was a yeast-like microbe and showed cellulase activity which might help the propagation of other yeasts on the brans. 5. The analytical data of fermented feed indicated the following order of usable value ; rice-wheat-barley bran 4:4:2, rice-wheat bran 5:5, rice-barley bran 5:5, rice-defatted rice bran 5:5. 6. the fermented feed were prepared by mixing brans, 0.3% ammonium sulfate and 5%(w/w) inoculum of yeast suspension in 4% glucose solution. Water content 70-80%, fermentation temperature 25-30.deg.C, and fermentation time 2-3 days were given. 7. The rice-wheat bran 5:5 and rice-barley bran 5:5 fermented feed showed 11, 17-11.45% protein increase, and the rice-barley-wheat bran 4:4:2 and rice-defatted bran 5:5 showed 3.75-6.03% protein increase. 8. The fermented feed prepared in this experiment by the author might work as a nutritive feed using microbial cell body, enzymes produced by microbes and other microbial cell constituents.

• Microbiology and Biotechnology Letters
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• v.33 no.1
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• pp.9-15
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• 2005

Chitin deacetylase (CDA; EC 3.5.1.41) catalyzes the hydrolysis of N-acetamide bonds of chitin, converting it to chitosan. Chitosan has several applications in areas such as biomedicine, food ingredients, cosmetics, pharmaceuticals, and agriculture. In this paper, occurrence, assay and purification protocols, enzymatic characteristics, substrate specificity, and mode of action of microbial CDAs have been described. Several lines of evidence have substantiated the biological roles involved in cell wall formation and plant-pathogen interactions for fungal CDAs. The gene structure of CDAs has been compared with other family 4 carbohydrate esterases which deacetylate a wide variety of acetylated poly/oligo-saccharides. The use of CDAs for the conversion of chitin to chitosan, in contrast to the presently used chemical procedure, offers the possibility of a controlled, non-degradable process, resulting in the production of well-defined chitosan oligomers and polymers. Insect pathogen that can secrete high levels of chitin-metab­olizing enzymes including CDA can be a possible alternative for new pest management tools.