• The Plant Pathology Journal
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• 제34권1호
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• pp.44-58
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• 2018

Pseudomonas chlororaphis 30-84 is a biological control agent selected for its ability to suppress diseases caused by fungal pathogens. P. chlororaphis 30-84 produces three phenazines: phenazine-1-carboxylic acid (PCA), 2-hydroxy-phenazine-1-carboxylic acid (2OHPCA) and a small amount of 2-hydroxy-phenazine (2OHPHZ), and these are required for fungal pathogen inhibition and wheat rhizosphere competence. The two, 2-hydroxy derivatives are produced from PCA via the activity of a phenazine-modifying enzyme encoded by phzO. In addition to the seven biosynthetic genes responsible for the production of PCA, many other Pseudomonas strains possess one or more modifying genes, which encode enzymes that act independently or together to convert PCA into other phenazine derivatives. In order to understand the fitness effects of producing different phenazines, we constructed isogenic derivatives of P. chlororaphis 30-84 that differed only in the type of phenazines produced. Altering the type of phenazines produced by P. chlororaphis 30-84 enhanced the spectrum of fungal pathogens inhibited and altered the degree of take-all disease suppression. These strains also differed in their ability to promote extracellular DNA release, which may contribute to the observed differences in the amount of biofilm produced. All derivatives were equally important for survival over repeated plant/harvest cycles, indicating that the type of phenazines produced is less important for persistence in the wheat rhizosphere than whether or not cells produce phenazines. These findings provide a better understanding of the effects of different phenazines on functions important for biological control activity with implications for applications that rely on introduced or native phenazine producing populations.

• 펄프종이기술
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• 제31권5호
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• pp.1-11
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• 1999

Wood components, cellulose and lignin, are degraded simultaneously and the general outline for the complementary character of carbohydrates and lignin decomposition as well as the existence of enzymatic systems combining these processes is still valid. The degradatiion of free cellulose or hemicellulose into monosaccharides has long been known to be relatively simple, but the mechanism of lignin degradatiion wasn ot solved very clearly yet. Anyway the biodegradation of woold constituents is understood at present as an enzymatic process. Kigninolytic activity has been correlated with lignin and manganese peroxidases. At present the attention is paid to laccase. Laccase oxidizes lignin molecule to phenoxy radicals and quinones . This oxidation can lead to the cleavageo f C-C or C-O bonds in the lignin phenyl-propane subunits, resulting either in degradation of both side chains and aromatic rings, or in demethylation processes. The role of laccase lies in the "activation" of some low molecular weight mediators and radicals produced by fungal cultures. Such activated factors produced also in cooperation with other enzymes are probably exported to the wood environment where they work in degradation processes as the ' enzyme messengers." It is worth mentioning that only fungi possessing laccase show demethylating activity. Thus demethylation, the process important for ligninolysis, is probably caused exclusively by laccase. Under natural conditions laccase seems to work with other fungal enzymes , mediators and mediating radicals. It has shown the possibility of direct Bjrkman lignin depolymerization by cooperative activity of laccase and glucose oxidase.

• 한국식품영양과학회지
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• 제33권1호
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• pp.41-46
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• 2004

전통된장과 공장산 된장 제품, 메주와 Koji, 그리고 된장발효공정에서의 혈전용해효소 활성과 microflora의 상관관계를 조사하였다. 전통된장의 혈전용해 활성은 평균 2.42 unit/g으로 공장산 된장의 평균 1.58 unit/g보다 1 unit 이상 높은 분포를 나타내었으며 전통된장에서는 Bacillus의 밀도가 높았고 acid producing bacteria, 곰팡이, 효모는 모두 공장산 된장에서 높은 밀도를 나타내었다. 된장의 Bacillus group 분포와 혈전용해효소활성은 양의 상관관계를 나타내었으며 fungal group 분포와 혈전용해효소활성은 음의 상관관계를 나타내었다. 메주의 혈전용해 활성은 평균 6.54 unit/g수준으로 Koji의 1.46 unit/g보다 5 unit 이상 높은 분포를 나타내었으며 Bacillus의 서식밀도와 높은 상관관계를 보였다. 된장 발효과정 중 Bacillus와 곰팡이는 휴지 상태를 유지하였으며 혈전용해효소 활성도 담금 초기의 수준을 유지하였다. 결과적으로 된장의 혈전용해활성은 된장 담금 이전의 원료구성에 따라 결정되며, 메주나 Koji에서 유래된 혈전용해 효소는 된장의 발효과정에서도 계속 활성을 유지하는 것으로 확인되었다. 본 실험 결과, 혈전용해효소 활성이 높은 된장을 제조하기 위해서는 메주나 Koji의 제조공정에서 효소활성을 유도하여 된장 담금 시 첨가하는 공정의 설정이 유효할 것으로 제안하였다.

• Journal of Forest and Environmental Science
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• 제37권1호
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• pp.52-61
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• 2021

Decay fungi can decompose plant debris to recycle carbon in the ecosystem. Still, they can also be fungal pathogens, which can damage living trees and/or wood material and cause a large amount of timber loss. We isolated and identified basidiomycetous fungi from the decayed bark of Mongolian oak wrapped with sticky roll traps. The degrading enzyme activities were then tested for all fungal isolates. The decay ability of selected isolates was assessed based on the weight loss of wood discs after inoculating with culture suspension of decay fungi under the different humidity levels. A total of 46 basidiomycetous fungal isolates belonged to 12 species, and 10 genera were obtained from Jong Myo (16 isolates), Chang Kyung palace (7 isolates), Cheong Gye (10 isolates), and Gun Po (13 isolates). Gymnopus luxurians was the most dominant fungus in the present study, and this species distributed in all survey sites with 9 isolates in Jong Myo, followed by 3 isolates in Chang Kyung palace, while Cheong Gye and Gun Po had only 1 isolate each. Among 46 isolates, 44 isolates secreted at least one enzyme, while 25 isolates produced both cellulase and phenol oxidase enzymes, and 2 isolates produced neither. The assessment of decay ability by artificial inoculation indicated that the weight loss of wood discs was significantly influenced by humidity conditions when inoculated with bark decay fungi. The percent weight losses by G. luxurians inoculation in RH of 90-100% and RH of 65-75% were 4.61% and 2.45%, respectively. The weight loss caused by Abortiporus biennis were 6.67% and 0.46% in RH of 90-100% and RH of 45-55%, respectively. The humidity reduction approach should be applied for further studies to control the growth and spread of bark decay fungi on the trunks wrapped with sticky roll traps.

• Journal of Ecology and Environment
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• 제46권2호
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• pp.136-143
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• 2022

Background: In northern Thailand, the longan flower is the principal nectar source for honey production. Microorganisms play a critical function in the agricultural ecology. The morphological characteristics of fungal species found in longan pollen were studied. Aspergillus spp. were found to be invertase-producing strains and were employed in the longan syrup production process. The purpose of this study was to evaluate the effects of invertase-added longan syrup on the adult honey bee population numbers that were fed by this syrup for 16 weeks. Results: Different fungal species were found in longan pollen samples. Aspergillus was the main genus, with three predominant sections: Nigri, Flavi, and Terrei. Other isolated species were Trichoderma spp., Rhizopus spp., Neurospora spp., Chaetomium spp., Fusarium spp. and Penicillium spp. However, Aspergillus spp. is the only fungal species that produces the enzyme invertase. The invertase-producing strains belonging to the Aspergillus section Nigri were found to be A. niger LP5 with an optimum activity at pH 6.0 and 60℃. When A. niger LP5 invertase was used for longan syrup processing, the highest levels of glucose (3.45%) and fructose (2.08%) were found in invertase added longan syrup (C), while fresh (A) and boiled longan syrup (B) had lower contents of both sugars. The sucrose content was detected in (A) at 4.25%, while (B) and (C) were at 4.02% and 3.08%, respectively. An appropriate amount of sugar to feed and maintain the honey bee population was considered. The data showed no statistically significant differences between the two selected forms of longan syrup compared to the sugar syrup examined by the adult honey bee population. Conclusions: The main species of isolated fungi from longan pollen were Aspergillus spp. The discovery of an invertase-producing strain of A. niger LP5 has enabled its application for enzyme utilization in the invert sugar preparation process. The adult worker bee populations fed by longan syrup from both boiled and invertase-added sources showed an increasing trend. Artificial syrup made from longan fruit to feed honey bees when natural food sources are limited can be applied.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.652-655
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• 2005

This paper describes the development of an enzymatic assay system for the identification of inhibitors of isocitrate lyase (ICL), one of the key enzymes of the glyoxylate cycle that is considered as a new target for antifungal drugs. A 1.6 kb DNA fragment encoding the isocitrate lyase from Candida albicans ATCC10231 was amplified by PCR, cloned into a vector providing His-Patch-thioredoxin-tag at the N-terminus, expressed in Escherichia coli, and purified by metal chelate affinity chromatography. The molecular mass of the purified ICL was approximately 62 kDa, as determined by SDS-PAGE, and the enzyme activity was directly proportional to incubation time and enzyme concentration. The effects of itaconate-related compounds on ICL activity were also investigated. Among them, itaconic acid, 3-nitropropionate, and oxalate had strong inhibitory activities with $IC_{50}$ values of 5.8, 5.4 and $8.6\;{mu}g/ml$, respectively. These inhibitors also exhibited antifungal activity on YPD agar media containing acetate as a sole carbon source, albeit at high concentration. The results indicate that the C. albicans ICL may be a regulatory enzyme playing a crucial role in fungal growth and is a prime target for antifungal agents.

• Applied Biological Chemistry
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• 제28권2호
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• pp.98-105
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• 1985

소와 양의 Rumen에서 Hungate's roll tube 방법에 의해 통성 혐기성 섬유소 분해세균을 분리하였다. 가장 강한 섬유소 분해력을 갖는 균주를 선발하여 형태학적 배양학적 생리학적 특성 및 전자현미경사진을 검토하여 Cellulomonas fimi C-14으로 동정(同定)하였다. 분리된 C. fimi C-14의 균생육 및 효소생산은 $30^{\circ}C$, pH6.5에서 최대이었으며, 그의 조효소(組酵素)는 pH6.0, $40^{\circ}C$에서 최대 역가를 보였으며 그 $C_1,\;C_x,\;{\beta}-glucosidase$의 Activity 는 20.6, 227.6, 0.56 $(unit{\times}10^3/ml)$ 이었다. 곰팡이 Cellulase의 첨가로 Enzyme Activity가 증가하였으며, 현사시나무의 톱밥을 기질로 하여, 분리균과 S. cerevisiae DY2를 접종하여 Ethanol 발효생산시 ${\beta}-glucosidase$의 첨가로 상승효과를 보였으며, 이단계 발효법보다 동시 당화 발효법에 의한 Ethanol 생산이 더 좋았다.

• Journal of Microbiology and Biotechnology
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• 제21권9호
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• pp.960-967
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• 2011

Tannin acyl hydrolase, also known as tannase, is an enzyme with important applications in the food, feed, pharmaceutical, and chemical industries. However, despite a growing interest in the catalytic properties of tannase, its practical use is very limited owing to high production costs. Several studies have already demonstrated the advantages of solid-state fermentation (SSF) for the production of fungal tannase, yet the optimal conditions for enzyme production strongly depend on the microbial strain utilized. Therefore, the aim of this study was to improve the tannase production by a locally isolated A. niger strain in an SSF system. The SSF was carried out in packed-bed bioreactors using polyurethane foam as an inert support impregnated with defined culture media. The process parameters influencing the enzyme production were identified using a Plackett-Burman design, where the substrate concentration, initial pH, and incubation temperature were determined as the most significant. These parameters were then further optimized using a Box-Behnken design. The maximum tannase production was obtained with a high tannic acid concentration (50 g/l), relatively low incubation temperature ($30^{\circ}C$), and unique low initial pH (4.0). The statistical strategy aided in increasing the enzyme activity nearly 1.97-fold, from 4,030 to 7,955 U/l. Consequently, these findings can lead to the development of a fermentation system that is able to produce large amounts of tannase in economical, compact, and scalable reactors.

• 산업식품공학
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• 제13권4호
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• pp.320-325
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• 2009

활성글루텐을 첨가한 쌀가루에 검의 첨가가 쌀가루의 신속점도측정기(RVA) 호화양상과 farinograph 반죽특성에 미치는 영향을 조사하였다. 검의 첨가에 의해 쌀가루의 RVA 최고점도는 증가한 반면 setback은 약간 감소함을 나타내었다. 활성글루텐을 첨가한 쌀가루에 검의 첨가는 farinograph 수분흡수율을 증가시키고 반죽의 안정도를 증가시켜 반죽을 강하게 하는 효과를 부여하였다. 쌀가루에 활성글루텐을 14% 첨가하고 검, 유화제 및 효소제를 복합처리하여 쌀빵을 제조한 후 쌀빵의 부피와 저장 중 경도변화를 조사하였다. 쌀가루에 첨가하는 활성글루텐의 양이 감소함에 따라 쌀빵의 부피가 감소하였지만 검, 유화제 및 효소제를 복합첨가 함으로써 쌀빵의 부피를 현저히 개선시킬 수 있었다. 활성글루텐만을 첨가한 쌀빵은 저장 중에 경도가 급격히 상승하였으나 검, 유화제 및 효소제를 복합첨가하여 제조한 쌀빵은 저장 중에 경도의 증가 폭이 현저하게 감소함을 나타내었다. 따라서 적절한 검, 유화제, 효소제의 복합처리는 쌀빵의 부피와 경도 변화 등 쌀빵의 품질에 매우 긍정적인 영향을 주는 것으로 평가되었다.

• 한국식품영양과학회지
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• 제38권10호
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• pp.1438-1443
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• 2009

쌀빵 냉동반죽에 첨가제로 gum, 유화제 및 효소제를 복합처리하여 반죽한 후 $-20^{\circ}C$에서 냉동 보관하면서 냉동반죽의 저장기간에 따른 쌀빵의 품질 특성을 조사하였다. 유화제인 sodium stearoyl lactylate(SSL)와 gum류인 guar gum을 각각 0.5%, 그리고 효소제로 곰팡이 $\alpha$-amylase를 0.01% 수준으로 첨가하여 사용하였다. 냉동반죽의 저장 중 쌀빵의 부피는 냉동기간이 경과함에 따라 감소하였는데, 첨가제를 넣지 않은 대조구 반죽에 비해 guar gum+SSL+곰팡이 $\alpha$-amylase를 복합첨가 한 반죽이 냉동 4주 경과 후에도 쌀빵 제조시 부피의 감소폭이 크지 않은 것으로 나타났다. 쌀빵의 경도 변화에 있어서 대조구 냉동반죽의 냉동저장 기간이 증가함에 따라 그리고 쌀빵의 제조 후 시간이 경과할수록 경도의 변화가 큰 반면, guar gum+SSL 첨가한 쌀빵과 guar gum+SSL+곰팡이 $\alpha$-amylase를 복합첨가 한 쌀빵은 저장기간에 따른 경도의 증가폭이 현저하게 낮은 것으로 나타났다. Gum/유화제/효소제의 복합첨가는 쌀가루 냉동반죽의 저장기간 경과에 따른 쌀빵의 부피 감소를 개선하고 노화를 억제하는 효과를 주어 냉동반죽 쌀빵의 품질에 긍정적인 영향을 미치는 것으로 평가되었다.