• Korean Journal of Microbiology
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• v.49 no.4
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• pp.309-312
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• 2013

Fungal cell walls consist of various glucans and chitin. Fungi produce chitinases for their growth and development. The inky cap, Coprinellus congregatus, produces at least two different chitinases during its life cycle. Chitinase 1 (chi1) is expresses throughout its life cycle while chitinase 2 (chi2) is expressed at the mushroom autolysing phase. The cloned cDNA of chi1 is successfully expressed as a fusion protein with c-myc in Pichia pastoris, and purified by the affinity chromatography. The optimum pH and temperature of Chi1 was pH 8.0 and $35^{\circ}C$, respectively when 4-nitrophenyl N,N',N"-triacetyl-${\beta}$-D-chitotrioside was used as the substrate. The $K_m$ value and $V_{max}$ for the substrate was 0.780 mM and 0.10 OD $min^{-1}unit^{-1}$, respectively. The addition of purified Chi1 resulted in total growth inhibition against several plant pathogenic fungi such as Alternaria alternata, Fusarium graminearum and Trichoderma harzianum at the concentration of 60 ${\mu}g/ml$.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.285-292
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• 2018

In this study, for the purpose of decomposing food waste, the strain was screened from traditional fermented food and soils. The enzyme activity (protease, amylase, cellulase, lipase) experiment was carried out using the paper disc method in 212 strains isolated from 5% NaCl media. Among them, only the strains having enzyme activity of more than 2 (soil) or more than 4 (traditional fermented food) with the halozone of enzyme activity of 15 mm or more were selected first, and microorganism identification through 16S rRNA sequencing was performed. Finally, were identified such as Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus siamensis, Bacillus licheniformis, Bacillus aquimaris, Bacillus megaterium, Bacillus koreensis, Bacillus stratoshericus, Bacillus aryabhattai, Bacillus safensis, Marinobacter hydrocarbonoclasticus. 11 species of mixed strains were confirmed that the culture time was 24 hours, the incubation temperature was $30^{\circ}C$ and the optimum pH was 7.0. In order to confirm the degree of decomposition of standard food wastes (100 g) by treating 11 kinds of mixed strains (25%), solid content of more than $2000{\mu}m$ was determined to be 103 g for the sterilized water group and 18 g for the mixed strains group. And the rest was decomposed to a size of less than $2000{\mu}m$.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.512-518
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• 2015

Pine wilt disease (PWD) caused by pine wood nematode, Bursaphelenchus xylophilus, has become the most serious threat to pine trees in Korea. This study was subjected to investigate effective biological control agent against PWD. To select nematocidal bacteria against PWD, Bacillus licheniformis MH48 was selected among five bacteria due to its high nematocidal potential. B. licheniformis MH48 was tested for cell growth and protease activity to evaluate its nematicidal potential. In the B. licheniformis MH48, cell numbers were highest three days after incubation, while protease activity was highest after seven days. In the effect of different concentrations of B. licheniformis MH48 culture broth against B. xylophilus, 20% concentration of culture broth showed approximately 80% of pine wood nematode mortality compared to the control. Especially, pine wood nematode's cuticle layers were degraded two days after treatment of B. licheniformis MH48 culture broth. The present study suggests that B. licheniformis MH48 can be one of the potential biocontrol candidates against pine wood nematode due to its ability to produce protease.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.325-327
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• 2012

Experiments for growth inhibition of two different plant pathogenic fungal species, Alternaria alternata (KCTC26781) and Fusarium graminearum ZO3639 (type culture) and ASR1R1 (isolate from rice), by a chitinase (Chi2) expressed in the autolysing tissue of Coprinellus congregatus were carried out. In liquid media, Chi2 ($50{\mu}g/ml$) inhibited more than 90% of germination of A. alternata spore, and the growth of each fungal strain was totally inhibited by the addition of Chi2 at the concentrations of $70{\mu}g/ml$. When $6{\mu}g$ of Chi2 was added twice a day at the hyphal tip zone, both strains of F. graminearum showed growth inhibition as well as decreased hyphal branching.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.235-237
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• 2006

When fruit bodies of Coprinellus congregatus were matured, they were autolysed to form black ink. During the developmental changes, cell walls of basidia were degraded. Laccase formed melanin which was the typical black pigment of fungi, and chitinase hydrolyzed the chitin which was a component of fungal cell wall. When laccase and chitinase genes were used as the probe for the Northern analysis to confirm their expression during the fruit body development, both gene expressions were increased as the mushroom was getting matured.

• Korean Journal of Microbiology
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• v.52 no.2
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• pp.226-229
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• 2016

The growth of two different fungal species, human pathogenic Cryptococcus neoformans and plant pathogenic Alternaria alternata were inhibited by a chitinase (Chi2) expressed in the autolysing tissue of Coprinellus congregatus. The cell wall thickness was reduced (up to 32%) in C. neoformans compared with that of normal cell, and polysaccharide fibers located outside of the cell wall were also severely removed. The hyphal growth of A. alternata on agar plate was stopped by the enzyme. The allergic inflammation induced by A. alternata was reduced by the enzyme reaction when compared with untreated control in a mouse model.

• Polymer(Korea)
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• v.32 no.6
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• pp.544-548
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• 2008

The objective of this study is to obtain the anti-oxidant nanoparticles based on biocompatible polymers. It was chosen to conjugate with chitosan as the biodegradable polymer and lipoic acid as the hydrophobic anti-oxidant. Lipoic acid helps the regeneration of exogenous and endogenous anti-oxidants vitamin as well as glutathione and hence acts as antioxidant indirectly. Chitosan was prepared from chitin which was deacetylated under alkali solution for the various reaction time. Lipoic acid-chitosan complex was confirmed by $^1H$-NMR. The critical aggregation concentration was measured using pyrene and the values were about $5{\times}10^{-3}$ g/L. The particle shapes and sizes of the chitosan-lipoic acid nano-particles were about 135 nm that measured by DLS and TEM.

• The Korean Journal of Zoology
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• v.36 no.1
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• pp.123-132
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• 1993

곤충의 탈피작용에서 일어나는 키틴 분해대사를 구명하기 위한 목적으로 배추흰나비 (Pieris rupae L.)에서 3종의 서N-acetylglucosaminldase(El, Ell, Elll)를 분리, 정제하였다. Polvacrylamide gel 상에서 이들 효소의 활성은 기질과 triphenvltetrazolium chloride와의 반응 결과 생기는 발색정도로 확인하였다. 각각의 분자량은 76,000, 55,000, 35,000 da, pl 값은 모두 5.8이었으며 후p$\beta$GlcNAc와 각p$\beta$GaINAc에 대해서 다같이 기질특이성을 나타내었다. 또한 El과 Elll는 탈피 시기와 일치하는 전용 말기에 최대 활성을 나타내었으며 Ell는 용화 직후에 최대 활성을 나타내었다.

• Food Science and Industry
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• v.53 no.1
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• pp.43-55
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• 2020

Most reports demonstrated the substrate specificity-based kinetic properties of chitin or chitosan degrading enzymes. However, there is virtually less information on the high quality and quantity production of chitin or chitosan hydrolysates having a larger than (GlcN)₇ from the hydrolysis of high molecular weight chitosan using specific enzymes and their biological activity. Therefore, the production of such molecules and the discovery of such enzyme sources are very important. Fortunately, the author has established a mass production method of chitosan hydrolysates (GlcN)_n, n=2-13 that have been characterized as a potent antioxidant substance, as well as antifungal and antibacterial activities against Penicillium species and highly selective pathogenic bacteria. In addition, preclinical studies using (GlcN)_n, n=5-25 demonstrated that these molecules played a very important role in maintaining biometric balance. Collectively, it is implicated that the application of these mixed substances to foods with significant biological activity is very encouraging.

• Clean Technology
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• v.7 no.4
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• pp.281-290
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• 2001

A microwave-assisted process to prepare chitosan from natural crabshells has been investigated. This study was primarily to examine the effectiveness of microwave as clean energy for chitosan preparation. Several human-edible organic acids were used as clean catalyst, possibly to improve the current HCl-based hydrolysis process of polymeric chitosan. The microwave was found to be effective substantially in reducing the reaction time. Nonetheless, no beneficial effect of microwave other than time, such as the chemical selectivity, was hardly observed. The organic acids were very effective in the hydrolysis reaction of polymeric chitosan. Their catalytic behavior was greatly improved especially when reactions were performed under pressure. In the case of autoclave reaction for 60 minutes at $120^{\circ}C$, viscous solution of polymeric chitosan (mol. wt. > 300,000) turned into thin solutions of water-like viscosity, which means chitosan molecules were decomposed to very small-sized oligomers.