• Food Science and Biotechnology
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• 제16권3호
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• pp.482-484
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• 2007

To investigate production and hydrolysis of levan, the levansucrase enzymes from Zymomonas mobilis ATCC 10988 and Rahnella aquatilis ATCC 33071 were used. The optimum temperature of R. aquatilis levansucrase for levan formation was $37^{\circ}C$, whereas that of Z. mobilis was $4^{\circ}C$, under the experimental conditions. Both levansucrases also catalyzed the reverse levan hydrolysis reaction. Levan hydrolysis reactions from both levansucrases were temperature dependent; high temperature ($20^{\circ}C$) was more favorable than low temperature ($4^{\circ}C$) by 4 times. Fructose was the only product from hydrolysis reaction by both levansucrases, showing that both levansucrases mediated the hydrolysis reaction of exo-enzyme acting. In both enzymes, initial levan hydrolysis activity was almost accounted to 1% of initial levan formation activity. The results allow the estimation of the fructose release rate in enzyme processing conditions.

• Mycobiology
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• 제29권4호
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• pp.210-217
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• 2001

Seventy-three species and five varieties belonging to 36 genera were collected from leaf surfaces of banana plants on glucose and cellulose-Czapek's agar at $28^{\circ}C$. The results obtained from leaf surfaces(phyllosphere and phylloplane) were basically similar on the two types of media and the most common fungi were Alternaria, Aspergillus, Chaetomium, Cladosporium, Cochliobolus, Curvularia, Gibberella, Memnoniella, Mycosphaerella, Setosphaeria and Stachybotrys. The monthly counts of these fungi were irregularly fluctuated giving maxima at various months. Chaetomium globosum was in the top of fungi in producing both exo- and endo-$\beta$-l,4-glucanases among the 34 tested isolates obtained from leaves(phylloplane) on cellulose-Czapek's agar. Maximum production of these enzymes by C. globosum was 6 and 8 days after incubation at $25^{\circ}C$ with culture medium containing wheat bran as a carbon source and peptone as a nitrogen source and initially adjusted to pH 6.

• 한국균학회지
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• 제16권2호
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• pp.64-69
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• 1988

사과반점낙엽병균(班點落葉病菌) Alternaria mali의 iprodione 저항성균주중(抵抗性菌株中) 병원성(病原性)이 변화(變化)된 균주( 菌株)를 구하여 pectin질(質) 분해효소(分解酵素)의 활성(活性)과 병원성(病原性)간의 관계를 알아보았다. 인공배지(人工培地)에서는 병원성(病原性)이 큰 $S_1$과 $R_3$균주(菌株)가 병원성(病原性)이 작은 $R_8$균주(菌株)보다 효소활성(酵素活性)이 높았으며 endo-polymethylgalacturonase와 endo-polygal-acturonase의 활성(活性)은 3배 이상이었다. 그러나 pectinmethylesterase와 pectin Iyase의 활성(活性)은 $S_1$균주(菌株)가 $R_3$와 $R_8$보다 높게 나타났다. 증류수(蒸溜水)로 투석(透析)시킨 사과배지(培地)에서 각 균주(菌株)는 높아진 효소활성(酵素活性)을 보였으나 균의(菌) 생장(生長)은 감소(減少)하였다. 또한 iprodione을 첨가(添加)하므로써 감수성(感受性) 균주(菌株)인 $S_1$의 효소활성(酵素活性)과 균사생장(菌絲生長)은 감소(減少)되었으나, 저항성균수(抵抗性菌洙)중 병원성(病原性)이 큰 $R_3$균주(菌株)는 투석(透析)시킨 사과배지(培地)에서 exo-polygalacturonase를 제외(除外)한 효소(酵素)의 활성(活性)이 증가(增加)되었다.

• 한국식품저장유통학회지
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• 제8권2호
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• pp.131-139
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• 2001

Kiyomi tangor(Citus unshiu x sinensis) was stored at 3$\^{C}$ and 85% relative humidity, and the changes in firmness, pectin degrading enzymes activity and other physicochemical properties of citrus fruits during storage were investigated. Decay ratio and weight loss during 180 days’ storage were increased gradually to 13.0% and 12.9%, respectively. Firmness of fruits with 2 mm probe was decreased gradually from 808.7 g-force to 406.4 g-force, and moisture of peel and flesh were decreased from 76.5% to from 89.6% to 87.6% during storage, respectively. Exo-polygalacturonase activity of peel after 150 days’ storage were increased gradually to 558.09 units/100g. Pectin methylesterase activity of peel and flesh were increased from 14.7 units/g to 2.3 units/g, and from 9.4 units/ml to 2.7 units/ml at 150days’ storage, respectively. Endo-polygalacturonase activities were not changed notably during storage. Alcohol-insoluble solid(AIS) of peel was not changed notably. During storage of the fruits water soluble pectin(WSP) of peel and flesh were increased from 474.49 mg/100g to 614.29mg/100g, and from 66.91mg/100g to 92.74mg/100g as wet basis, respectively. Hexameta-phosphate soluble pectin(HMP) of peel were decreased from 405.5mg/100g to 270.43mg/100g, hydochloric acid soluble pectin(HSP) of peel was also decreased from 544.02mg/100g to 412.64mg/100g during storage. Total pectin substance(TPS) of peel and flesh were decreased from 1,424.01mg/100g to 1,297.36mg/100g, and from 165.51mg/100g to 171.54mg/100g, respectively. Composition ratio of pectin was in order of WSP > HSP > HMP.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2011년도 춘계학술발표회 논문집
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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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• 제8권6호
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• pp.568-574
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• 1998

Two types of chitosanases produced from Aspergillus fumigatus KH-94 were purified by ion exchange and gel permeation chromatography. Molecular weights of the enzymes are 22.5 kDa (chitosanase I) and 108 kDa (chitosanase II). pI, optimum pH, and temperature of chitosanase I are 7.3, 5.5, and 70-$80^{\circ}C$, respectively, and those of chitosanase II are 4.8, 4.5~5.5, and 50~$60^{\circ}C$, respectively. Activities of both chitosanases were increased by $Mn^{2+}$ but inhibited by $Cu^{2+}$ and $Hg^{2+}$ . Chitosanase I has endo-splitting activity that hydrolyzes chitopentaose, chitohexaose, and chitosan to chitobiose, chitotriose, and chitotetraose, whereas chitosanase II has exo-splitting activity that hydrolyzes chitobiose and chitosan to glucosamine. Chitosanase II was found to have transglycosylation activity also in the reaction of 2% more chitooligosaccharides as a substrate and at the initial reaction. The higher degree of deacetylation, the stronger activities of chitosanase Iand II toward chitosans. Both chitosanases could hydrolyze chitosan and glycol chitosan but not chitin, cellulose, and carboxymethyl cellulose. To produce higher degree of polymerization of chitooligosaccharides, chitosanase I was used and yielded 80% of recovery.

• Journal of Microbiology and Biotechnology
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• 제17권3호
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• pp.481-489
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• 2007

[ $\alpha$ ]-L-Arabinofuranosidases (AFases; EC 3.2.1.55) are exo-type enzymes, which hydrolyze terminal nonreducing arabinose residues from various polysaccharides such as arabinan and arabinoxylan. Genome-wide BLAST search showed that various bacterial strains possess the putative AFase genes with well-conserved motif sequences at the nucleotide and amino acid sequence levels. In this study, two sets of degenerate PCR primers were designed and tested to detect putative AFase genes, based on their three highly conserved amino acid blocks (PGGNFV, GNEMDG; and DEWNVW). Among 20 Bacillus-associated species, 13 species were revealed to have putative AFase genes in their genome and they share over 67% of amino acid identities with each other. Based on the partial sequence obtained from an isolate, an AFase from Geobacillus sp. was cloned and expressed in E. coli. Enzymatic characterization has verified that the resulting enzyme corresponds to a typical AFase. Accordingly, degenerate PCR primers developed in this work can be used for fast, easy, and specific detection and isolation of putative AFase genes from bacterial cells.

• 임산에너지
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• 제20권2호
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• pp.20-27
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• 2001

글루코스 생산을 위한 효과적인 방법을 개발하기 위해서 cellulase에 의한 현사시 나무의 효소가수분해를 실시하였다. 목재의 효소가수분해는 미생물이 생산한 효소를 사용하여 글루코스를 생산하는 반응이다. 이렇게 얻어진 글루코스는 발효에 의해 쉽게 에탄올로 변환시킬 수 있다. 에탄올은 아세톤이나 부탄올, 시트릭산 그리고 락틴산을 제조하는 원료물질이나 석유자원을 대체할 수 있는 대체에너지 자원이다. 셀룰로오스의 효소가수분해 기작은 endo-cellulase, exo-cellulase 그리고 β-D-glucosidase라는 세 개의 서로 다른 형태의 효소가 연속적인 반웅에 의해 일어난다고 설명되어지고 있다. 본 실험의 목적은 다양한 농도의 수산화나트륨으로 현사시나무를 전처리 하여 이러한 전처리가 셀룰로오스의 결정화도와 리그닌함량에 미치는 영향과 가수분해율과의 관계를 조사하였다.

• The Plant Pathology Journal
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• 제24권2호
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• pp.143-151
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• 2008

To define the functions of the rpf genes in Xanthomonas oryzae pv. oryzae (Xoo), which regulates pathogenicity factors in Xanthomonas campestris pv. campestris (Xcc), marker-exchange mutants of each rpf gene were generated. When the mutants were inoculated on a susceptible cultivar, the lesion lengths caused by the rpfB, rpfC, rpfF, and rpfG mutants were significantly smaller than those caused by the wild type, whereas those caused by the rpfA, rpfD, and rpfI mutants were not. Several virulence determinants, including extracellular polysaccharide (EPS) production, xylanase production, and motility, were significantly decreased in the four mutants. However, the cellulase activity in the mutants was unchanged. Complementation of the rpfB and rpfC mutations restored the virulence and the expression of the virulence determinants. Expression analysis of 14 virulence genes revealed that the expression of genes related to EPS production (gumG and gumM), LPS (xanA, xanB, wxoD, and wxoC), phytase (phyA), xylanase (xynB), lipase (lipA), and motility (pitA) were reduced significantly in the mutants rpfB, rpfC, rpfF, and rpfG. In contrast, the expression of genes related to cellulase (eglxob, clsA), cellobiosidase (cbsA), and iron metabolism (fur) was unchanged. The results of this study clearly show that rpfB, rpfC, rpfF, and rpfG are important for the virulence of Xoo KACC10859, and that virulence genes are regulated differently by the Rpfs.

• 한국식품과학회지
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• 제16권1호
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• pp.41-46
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• 1984

Aspergillus niger sherumanni IAM 2059가 분비하는 펙틴질분해효소 중에서 endo-polygalacturonase 를 Sephadex G-100, DEAE-Sephadex A-50을 이용하여 분리하고 점도감소와 분해산물분석을 통해 효소의 특성을 조사하였다. Chromatography를 통해 얻은 3 개의 역가 fraction (F-A, F-I 및 F-II) 은 각각 exo형 효소, eodo-polygalacturonase, endo-polymethylgalacturonase 이었다. endo-polygalacturonase의 역가 최적 pH는 환원당 생성으로는 pH4.2 근방이었고 점도감도로는 pH4.7 근방이었다. 이 효소의 Z-value는 $7.5^{\circ}C$이고 $D40^{\circ}C$는 240sec 이며 $40^{\circ}C$에서 활성화엔트로피(Enthalphy of activation) 217.3KJ/mol, 활성화엔트로피(Entropy of activation) 409.2J/mol.K, 활성화자유에너지(Free energy activation) 89.2KJ/mol 이었다.