• 농약과학회지
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• 제21권1호
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• pp.90-96
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• 2017

국내에서 생산하는 과채류에서 발생되는 잿빛곰팡이병은 명확한 생물학적 방제 방법으로 제시된 바가 없는 실정이다. 국내에서 사용 및 개발되고 있는 화학적 방제 약제의 경우 약제저항성 병원균의 출현이 지속되고 있는 상황이다. 또한 임의 기생성으로 인해 기주의 여부에 상관 없이 생존이 가능하므로 경종적 방제 또한 어려운 실정이다. 이에 본 연구에서는 토마토 꽃에 정착력이 우수한 길항미생물을 선발하기 위해 시설재배지의 토마토 화기와 벌집 시료로 미생물을 분리하여 방제균을 선발하였다. 총 6개월의 토마토 재배기간 중 꽃에서 1,004개 균주, 벌집에서 925균주를 분리하여, 잿빛곰팡이 병원균을 억제력이 우수한 6균주를 선발하였다. 선발된 6균주는 잿빛곰팡이 병원균에 대한 항균활성이 우수할 뿐 아니라, cellulase와 protease의 활성 또한 우수한 것으로 검증되었다. 선발된 균주는 Paenibacillus polymyxa 로 동정 되었으며, 토마토의 잿빛곰팡이 발병률을 약 75% 감소시키는 효과를 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.251-261
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• 2017

Initially, we screened 18 Aspergillus sojae-like strains from Aspergillus spp. isolated from meju (Korean traditional fermented soybean brick) according to their morphological characteristics. Because members of Aspergillus section Flavi are often incorrectly identified because of their phylogenetic similarity, we re-identified these strains at the morphological and molecular genetic levels. Fourteen strains were finally identified as A. sojae. The isolates produced protease and ${\alpha}-amylase$ with ranges of 2.66-10.64 and 21.53-106.73 unit/g-initial dry substrate (U/g-IDS), respectively, which were equivalent to those of the koji (starter mold) strains employed to produce Japanese soy sauce. Among the isolates and Japanese koji strains, strains SMF 127 and SMF 131 had the highest leucine aminopeptidase (LAP) activities at 6.00 and 6.06 U/g-IDS, respectively. LAP plays an important role in flavor development because of the production of low-molecular-weight peptides that affect the taste and decrease bitterness. SMF 127 and SMF 131 appeared to be non-aflatoxigenic because of a termination point mutation in aflR and the lack of the polyketide synthase gene found in other A. sojae strains. In addition, SMF 127 and SMF 131 were not cyclopiazonic acid (CPA) producers because of the deletion of maoA, dmaT, and pks/nrps, which are involved in CPA biosynthesis. Therefore, A. sojae strains such as SMF 127 and SMF 131, which have high protease and LAP activities and are free of safety issues, can be considered good starters for soybean fermentations, such as in the production of the Korean fermented soybean products meju, doenjang, and ganjang.

• 한국균학회지
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• 제30권2호
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• pp.147-151
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• 2002

Trichoderma속 균주는 느타리버섯 재배 시 발생되는 버섯 푸른곰팡이병의 주요 원인균이다. 후발효된 버섯 배지로부터 버섯 푸른곰팡이병균에 항균활성을 나타내는 길항세균(KATB 99121, KATB 99122 및 KATB 99123)을 분리하였다. 분리세균 중 KATB 99121은 T. harzianum(4균주). T. viride 및 T. hamatum과 동물병원성 곰팡이 Candida albicans에 대하여 우수한 억제 활성이 관찰되었고, 특히 세균의 배양상등액 접종실험에서 강한 항균활성을 보였다. 또한, KATB 99121은 전분, 단백질 및 섬유소를 분해하는 효소를 세포외로 분비하는 것으로 관찰되었고, KATB 99122와 KATB 99123은 전분, 단백질, 섬유소 분해효소는 물론 지질 분해효소도 분비하고 있었으며 ${\beta}$-glucosidase활성도 높은 것으로 확인되었다. 앞으로 이들 길항세균들을 이용하여 느타리버섯 푸른곰팡이병 방제를 위한 미생물 살균제의 개발에 대한 연구를 수행할 예정이다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 춘계학술대회 및 임시총회
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• pp.25-25
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• 2014

Koji molds are comprised of yellow, black and white. Black and white koji molds were recently re-visited by this author and it is concluded that they consists of Aspergillus luchuesnsis, A. niger and A. tubingensis, and the most important species for alcoholic beverage production is A. luchuensis. In the case of yellow koji mold, it is comprised of Aspergillus oryzae, A. sojae and A. tamari. In the case of A. sojae, the species is scarcely isolated from nature and rarely used for industry in Korea. Aspergillus tamari is often isolated from traditional Korean Meju, a fermented soybean product, and the classification of the species is clear. However, in the case of A. oryzae, differentiation between A. oryzae and A. flavus is still in controversy. In this study, we collected 415 strains of Aspergillus flavus/oryzae complex from air, rice straw, soybean, corn, peanut, arable soil and Meju in Korea and we examined the aflatoxin producing capacity of the strains. The norB-cypA, omtA and aflR genes in the aflatoxin biosynthesis gene cluster were analyzed. We found that 367 strains (88.4%) belonged to non-aflatoxigenic group (Type I of norB-cypA, IB-L-B-, IC-AO, or IA-L-B- of omtA, and AO type of aflR), and only 48 strains (11.6%) belonged to aflatoxin-producible group (Type II of norB-cypA, IC-L-B+/B- or IC-L-B+ of omtA, and AF type of aflR). In the case of A. flavus/oryzae strains from Meju, almost strains (178/192, 92.7%) belonged to non-aflatoxigenic group and only 14 strains (7.3 %) belonged to aflatoxin-producible group. It is proposed in this study that non-aflatoxigenic strain from Meju is classified as A. oryzae, considering that Meju is food material.

• Journal of Applied Biological Chemistry
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• 제61권1호
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• pp.69-73
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• 2018

표고버섯(Lentinus edodes)은 원목이나 톱밥배지를 사용하여 재배한다. 이 배지에 푸른곰팡이(Trichoderma)가 감염되면 표고버섯의 생장을 크게 억제한다. 버섯은 신선식품이기 때문에 푸른곰팡이를 방제하기 위한 항생제와 화학약품의 사용은 허용되지 않는다. Pseudomonas tolaasii에 의해 분비되는 펩티드 독소인 톨라신과 톨라신 유사체들은 항진균 활성을 가져 푸른곰팡이병 방제에 성공적이었다. 푸른곰팡이 Trichoderma harzianum H1에 톨라신 펩티드를 처리하였을 때 곰팡이의 성장은 효과적으로 억제되었고, 실제 톱밥배지에서 균주 배양액을 푸른곰팡이 균사에 분사하였을 때, 균사 성장은 완벽하게 억제되었다. 특히, P. tolaasii 6264와 HK11 균주의 배양 추출액을 혼합하여 처리하였을 때에 항진균 활성이 크게 증가하였다. 따라서 이러한 균주들과 펩티드 독소들은 푸른곰팡이의 성장을 억제할 수 있고, 표고버섯 재배에서 푸른곰팡이병을 방제하기 위한 좋은 후보가 될 수 있다.

• 한국주조공학회지
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• 제22권4호
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• pp.192-199
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• 2002

Dimensional defects of castings are mainly due to the stresses and strains caused by a nonuniform temperature distribution and phase transformation during solidification and cooling, and by mechanical constraint between the mold and casting. It is, however, nearly impossible to trace movements of the casting and mold during solidification and cooling by experimental measurements for castings with complex shape. Two and three dimensional deformation analyses of the casting and the mold were performed using commercial finite element code, MARC. It was possible to calculate deformation and temperature distribution in the casting and mold simultaneously. Cooling curves of the casting obtained by calculation were close to that measured in the field since it was possible to treat latent heat evolution of the casting which could be divided into two parts, primary and eutectic parts. Mold bent inward just after pouring due to the temperature gradient across the mold thickness, and mold returned to its previous position with time. Plastic deformation occurred at the part of the casting where solidification was slow.

• 식물병연구
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• 제20권3호
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• pp.182-188
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• 2014

Because bacterial isolates from only a few genera have been developed commercially as biopesticides, discovery and characterization of novel bacterial strains will be a key to market expansion. Our previous screen using plant bioassays identified 24 novel biocontrol isolates representing 12 different genera. In this study, we characterized the 3 isolates showing the best biocontrol activities. The isolates were Pantoea dispersa WCU35, Proteus myxofaciens WCU244, and Exiguobacterium acetylicum WCU292 based on 16S rRNA sequence analysis. The isolates showed differential production of extracellular enzymes, antimicrobial activity against various fungal or bacterial plant pathogens, and induced systemic resistance activity against tomato gray mold disease caused by Botrytis cinerea. E. acetylicum WCU292 lacked strong in vitro antimicrobial activity against plant pathogens, but induced systemic resistance against tomato gray mold disease. These results confirm that the trait of biological control is found in a wide variety of bacterial genera.

• Mycobiology
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• 제46권1호
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• pp.33-46
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• 2018

Gray mold (Botrytis cinerea) is one of the most common diseases of strawberries (Fragaria${\times}$ananassa Duchesne) worldwide. Although many chemical fungicides are used for controlling the growth of B. cinerea, the risk of the fungus developing chemical resistance together with consumer demand for reducing the use of chemical fungicides have necessitated an alternative method to control this pathogen. Various naturally occurring microbes aggressively attack plant pathogens and benefit plants by suppressing diseases; these microbes are referred to as biocontrol agents. However, screening of potent biocontrol agents is essential for their further development and commercialization. In this study, 24 strains of yeast with antagonistic ability against gray mold were isolated, and the antifungal activity of the volatile and diffusible metabolites was evaluated. Putative mechanisms of action associated with the biocontrol capacity of yeast strains against B. cinerea were studied through in vitro and in vivo assays. The volatile organic compounds produced by the Galactomyces candidum JYC1146 could be useful in the biological control of plant pathogens and therefore are potential alternative fungicides with low environmental impact.

• Journal of Applied Biological Chemistry
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• 제60권2호
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• pp.149-153
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• 2017

원목과 톱밥배지에서 푸른곰팡이의 오염과 성장은 표고버섯의 생장을 심하게 저해할 수 있다. 표고버섯 재배에서 푸른곰팡이병의 방제를 위하여 농약과 항생제와 같은 화학 약품의 사용은 일반적으로 허용되지 않는다. 본 연구에서는 푸른곰팡이병의 방제를 위하여 느타리버섯에서 갈반병을 일으키는 세균성 병원균을 분리하고 이들의 펩티드 독소를 분리하였다. Pseudomonas tolaasii 균주들은 항진균 활성을 갖는 톨라신 및 이와 구조적 유사체인 다양한 펩티드 독소를 분비한다. 이러한 펩티드들은 표고버섯의 생장에는 영향을 주지 않는다는 것이 알려져 있다. 펩티드 독소들을 Trichoderma harzianum H1 푸른곰팡이에 처리하였을 때, 푸른곰팡이의 성장을 저해하였다. 펩티드를 분비하는 20 종의 P. tolaasii 균주 중에서 강, 중, 약의 항진균 활성을 가진 균주의 수는 각각 8, 5, 7 종으로 나타났다. 표고버섯을 재배하는 동안에, 펩티드 독소를 함유한 세균 배양액에서 세균을 제거한 배양원액을 톱밥배지 표면에 자란 푸른곰팡이 균사에 분무하였다. 배양원액은 푸른곰팡이의 성장은 억제할 수 있는 반면, 표고버섯 생장과 생산에는 영향을 주지 않았다. 펩티드 독소를 함유하는 배양원액은 곰팡이의 흰색 균사체를 노란색의 마른 딱지로 변화시켰고, 이것은 펩티드 독소가 강력한 항진균 활성과 살균 활성을 갖고 있음을 보여준다.

• KSBB Journal
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• 제27권5호
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• pp.301-307
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• 2012

The hyphal growth, production of color pigments and monacolin K by Monascus strains were investigated in liquid medium. Thirty five different strains were collected and cultured in potato dextrose yeast extract broth (PDYB), potato dextrose broth (PDB) and malt extract broth (MEB) medea at $25^{\circ}C$ for 7 days. The growth rates of most of strains were highest in PDYB medium. Growth rate as well as pigment production were influenced by suspension conditions of mycelia during liquid cultivation. Most of strains producing monacolin K corresponded to strains producing red pigment highly and showing more pH changes of liquid media. Monacolin K produced from strains was detected in culture broth as well as mycelia. Any citrinin was not detected in monacolin K producing strains. These results imply that the selection of the strains producing red pigment highly and showing more pH changes in liquid cultivation could be applied for primary screening of Monascus strains for preparation of red mold rice.