• The Korean Journal of Food And Nutrition
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• v.16 no.4
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• pp.437-443
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• 2003

Chitooligosaccharides were prepared by enzymatic hydrolyzing of crab shell chitosan. Low molecular weight chitooligosaccharides(LMW-chitooligosaccharides), 64.3% of which was composed of trimer, tetramer, and pentamer, was obtained by hydrolyzing chitosan with the chitosanase originated Bacillus pumilus BN-262. High molecular weight chitooligosaccharides(HMW-chitooligosaccharides), 49.3% of which was composed of chitooligosaccharides over heptamer, was obtained by hydrolyzing chitosan with the cellulase originated Trichoderma viride. Acute oral toxicity of chitooligosaccharides were tested in mice. Chitooligosaccharides did not have any toxic effect in mice and oral LD$\_$50/ value of chitooligosaccharides was over 5.0g/kg in mice.

• Microbiology and Biotechnology Letters
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• v.46 no.1
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• pp.45-50
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• 2018

The chitosanase gene (btbchito) of Bacillus thuringiensis BMB171 was cloned and heterologously expressed in the yeast Pichia pastoris. After purification, about 300 mg of recombinant chitosanase was obtained from the 1-1 culture medium with a specific activity of 240 units/mg. Results determined by the combined use of thin layer chromatography (TLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) showed that the chitooligosaccharides (COSs) obtained by chitosan (N-deacetylated by 70%, 80%, and 90%) hydrolysis by rBTBCHITO were comprised of oligomers, with degrees of polymerization (DP) mainly ranging from trimers to heptamers; high molecular weight chitopentaose, chitohexaose, and chitoheptaose were also produced. Hydrolysis products was also deduced using MS since the COSs (n) are complex oligosaccharides with various acetyl groups from one to two, so the non-acetyl COSs (GlcN)n and COSs with more acetyls (> 2) were not detected. The employment of this method in the production of high molecular weight COSs may be useful for various industrial and biological applications, and the activity of chitosanase has great significance in research and other applications.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.86-87
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• 2000

Chitosan (deacetylated form of chitin) possesses strong antibacterial activities such as antimicrobial effect, antifungal effect and the induction of plant defense response. Chitosan itself, however, has high molecular weight and viscosity as well as water-insolubility, These natures may restrict applications in various fields, especially in in vivo system. While the hydrolysates of chitosan, chitooligosaccharides (COS) are not only lower in the molecula. weight and viscosity, but also water-soluble. Thus, they would be expected more efficient absorption in vivo. Besides several documents have been reported antibacterial activities of COS against microorganisms (Kendra et al., 1989; Uchida et al., 1989). (omitted)

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.2
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• pp.236-243
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• 2004

Antimicrobial effect of chitosan and its oligosaccharides was examined on Vibrios sp., Edwardsiella tarda and Streptococcus sp., which are major pathogenic bacteria inducing bacterial diseases of acquacultured flounder. Chitosan oligosaccharides (COS ) were produced by enzymatic hydrolysis of chitosan in an ultrafiltration mombrane bioreactor system which was established with three membranes with different molecular weight cut-off (MWCO) 1,000, 5,000 and 10,000, and fractionated into three kinds of COS, based on their molecular weight sizes. The three kinds of COS were as follows : relatively high molecular weight COS [HMW-COS, molecular weight distribution of 7,000 to 24,000 Da〕, medium molecular weight COS 〔MMW-COS, 1,500 to 6,000 Da〕, and low molecular weight COS 〔LMW-COS, 1,000 to 1,500 Da). Chitosan and HMW-COS effectively inhibited the growths of Vibrio sp. and Streptococcus sp. and their antimicrobial activities were superior to the others with smaller molecular weights. This result suggested that antimicrobial effect of chitosan preparations extremely depend on their molecular weight sizes. Antimicrobial effect of chitosan and HMW-COS on E. tarda was improved by longer inoculation times. Scanning electron microscopy in morphological change of E. tarda treated with chitosan preparations showed that chitosan and HMW-COS bound to the cells and suppressed the growth of the cells. This observation appears to prove the fact that positive charged amines of chitosan electrostatically bind to negative charged compounds of cell walls.

• Journal of Microbiology and Biotechnology
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• v.7 no.2
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• pp.107-113
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• 1997

A strain producing a high amount of chitinase was isolated from soil, identified as Pseudomonas sp., and tentatively named Pseudomonas sp. YHS-A2. An extracellular chitinase of Pseudomonas sp. YHS-A2 was purified according to the procedure of ammonium sulfate saturation, affinity adsorption, Sephadex G-100 gel filtration and Phenyl-sepharose CL-4B hydrophobic interaction column chromatography. The molecular weight of the purified enzyme was estimated to be 55 kDa on SDS-PAGE was confirmed by active staining. Optimal pH and temperature of the enzyme are pH 7.0 and $50^{\circ}C$, respectively, and the enzyme is stable between pH 5.0 and 8.0 and below $50^{\circ}C$. The main products of colloidal chitin by the chitinase were N-acetyl-D-glucosamine and N,N'-diacetylchitobiose both of which were detected by HPLC analysis. The enzyme is supposed to be a random-type endochitinase which can degrade any position of ${\beta}$-l,4-linkages of chitin and chitooligosaccharides. The chitinase inhibited the growth of some phytopathogenic fungi, Fusarium oxysporum, Botrytis cineria, and Mucor rouxii and these antifungal effects were thought to be due to the characteristics of endochitinase.