• Mycobiology
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• 제49권2호
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• pp.151-160
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• 2021

Despite recent studies, relatively few are known about the diversity of fungal communities in the deep Atlantic Ocean. In this study, we investigated the diversity of fungal communities in 15 different deep-sea sediments from the South Atlantic Ocean with a culture-dependent approach followed by phylogenetic analysis of ITS sequences. A total of 29 fungal strains were isolated from the 15 deep-sea sediments. These strains belong to four fungal genera, including Aspergillus, Cladosporium, Penicillium, and Alternaria. Penicillium, accounting for 44.8% of the total fungal isolates, was a dominant genus. The antiaflatoxigenic activity of these deep-sea fungal isolates was studied. Surprisingly, most of the strains showed moderate to strong antiaflatoxigenic activity. Four isolates, belonging to species of Penicillium polonicum, Penicillium chrysogenum, Aspergillus versicolor, and Cladosporium cladosporioides, could completely inhibit not only the mycelial growth of Aspergillus parasiticus mutant strain NFRI-95, but also the aflatoxin production. To our knowledge, this is the first report to investigate the antiaflatoxigenic activity of culturable deep-sea fungi. Our results provide new insights into the community composition of fungi in the deep South Atlantic Ocean. The high proportion of strains that displayed antiaflatoxigenic activity demonstrates that deep-sea fungi from the Atlantic Ocean are valuable resources for mining bioactive compounds.

• Journal of Microbiology and Biotechnology
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• 제31권5호
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• pp.645-658
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• 2021

Porins are essential for the viability of Gram-negative bacteria. They ensure the uptake of nutrients, can be involved in the maintenance of outer membrane integrity and define the antibiotic or drug resistance of organisms. The function and structure of porins in proteobacteria is well described, while their function in photoautotrophic cyanobacteria has not been systematically explored. We compared the domain architecture of nine putative porins in the filamentous cyanobacterium Anabaena sp. PCC 7120 and analyzed the seven candidates with predicted OprB-domain. Single recombinant mutants of the seven genes were created and their growth capacity under different conditions was analyzed. Most of the putative porins seem to be involved in the transport of salt and copper, as respective mutants were resistant to elevated concentrations of these substances. In turn, only the mutant of alr2231 was less sensitive to elevated zinc concentrations, while mutants of alr0834, alr4741 and all4499 were resistant to high manganese concentrations. Notably the mutant of alr4550 shows a high sensitivity against harmful compounds, which is indicative for a function related to the maintenance of outer membrane integrity. Moreover, the mutant of all5191 exhibited a phenotype which suggests either a higher nitrate demand or an inefficient nitrogen fixation. The dependency of porin membrane insertion on Omp85 proteins was tested exemplarily for Alr4550, and an enhanced aggregation of Alr4550 was observed in two omp85 mutants. The comparative analysis of porin mutants suggests that the proteins in parts perform distinct functions related to envelope integrity and solute uptake.

• The Plant Pathology Journal
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• 제38권4호
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• pp.345-354
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• 2022

NADPH oxidase (Nox) complexes are known to play essential roles in differentiation and proliferation of many filamentous fungi. However, the functions of Noxs have not been elucidated in Colletotrichum species. Therefore, we set out to characterize the roles of Nox enzymes and their regulators in Colletotrichum scovillei, which causes serious anthracnose disease on pepper fruits in temperate and subtropical and temperate region. In this study, we generated targeted deletion mutants for CsNox1, CsNox2, CsNoxR, and CsNoxD via homologous recombination. All deletion mutants were normal in mycelial growth, conidiation, conidial germination, and appressorium formation, suggesting that CsNox1, CsNox2, CsNoxR, and CsNoxD are not involved in those developmental processes. Notably, conidia of 𝜟Csnox2 and 𝜟Csnoxr, other than 𝜟Csnox1 and 𝜟Csnoxd, failed to cause anthracnose on intact pepper fruits. However, they still caused normal disease on wounded pepper fruits, suggesting that Csnox2 and CsnoxR are essential for penetration-related morphogenesis in C. scovillei. Further observation proved that 𝜟Csnox2 and 𝜟Csnoxr were unable to form penetration peg, while they fully developed appressoria, revealing that defect of anthracnose development by 𝜟Csnox2 and 𝜟Csnoxr resulted from failure in penetration peg formation. Our results suggest that CsNox2 and CsNoxR are critical for appressorium-mediated penetration in C. scovillei-pepper fruit pathosystem, which provides insight into understanding roles of Nox genes in anthracnose disease development.

• 한국수산과학회지
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• 제14권1호
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• pp.24-28
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• 1981

1980년 6월 20일부터 14일간, 어 청도산 미역을 모조로 유주자를 착생시킨 후, Keinetin, IAA및 2.4-D의 농도별배지에서 배양하여 배우체의 생장에 미치는 영향을 조사하였파. 그 결과를 간추리면 다음과 같다. 1. 발아율은 거의 $100\%$였으나 2.4-D 0.1 mg/l 또는 Keinetin 0.1, 1.0 또는 5.0 mg/1 배지에서는 발아관이 신장하지 않고 착생육자에서 바로 신생세포가 형성되었다. 2. 전체적 생장효과는 Keinetin 0.1 mg/l 배지에서 대조대비 $248.9\%$를 기록, 최고치를 표시하였고, IAA 1.0 mg/1($243.3\%$) 2.4-D에서는 0.05mg/l ($205.6\%$)가 가장 좋았다. 3. 웅성배우체에 미친 생장효과는 IAA 1.0mg/l가 $276.8\%$로서 최고치를 나타냈고 Keinetin 0.1mg/l($263.6\%$), 0.5mg/1($248.3\%$), 2.4-D 0.05mg/1($227.8\%$)의 순이 었다. 4. 자성배우체에서는 Keinetin이 효과적으로 작용하여 5.0mg/1($239.0\%$), 0.1mg/l ($222.0\%$), 0.05mg/l ($209.8\%$)를 기록 현저한 공률을 보여주고 있으나 IAA에서는 0.5mg/l($195.1\%$), 2.4-D에서는 0.05mg/1($164.6\%$)가 최고지를 기록하고 있어 대체로 웅성배우체에 비해 저조하고 배우체의 성에 따라 식물Hormone의 생장효과는 그 종류와 농도를 달리한다. 5. 생장조해농도는 2.4-D 0.5mg/l이상, IAA 0.5mg/1이상이고, Keinetin은 10.0mg/l 이상의 농도에서 생장이 크게 억제하고 있다. 6. 유효농도범의는 Keinetinol 0.01mg/1-5.0mg/l로 가장 넓고 공률곡선이 대단히 완만하며 IAA도 비교적 넓어 0.02mg/1와 1.0mg/l를 정점으로 생장효율 곡선이 S자형을 보여주고 있으나 2.4-D는 극히 좁아 0.05mg/1를 중심으로 급격히 저하하여 삼각곡선을 표시한다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 추계학술대회 및 정기총회
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• pp.15-15
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• 2014

Fusarium graminearum (teleomorph Gibberella zeae) is an important plant pathogen that causes head blight of major cereal crops such as wheat, barley, and rice, as well as causing ear and stalk rot on maize worldwide. Plant diseases caused by this fungus lead to severe yield losses and accumulation of harmful mycotoxins in infected cereals [1]. Fungi utilize spore production as a mean to rapidly avoid unfavorable environmental conditions and to amplify their population. Spores are produced sexually and asexually and their production is precisely controlled. Upstream developmental activators consist of fluffy genes have been known to orchestrate early induction of condiogenesis in a model filamentous fungus Aspergillus nidulans. To understand the molecular mechanisms underlying conidiogenesis in F. graminearum, we characterized functions of the F. graminearum fluffy gene homologs [2]. We found that FlbD is conserved regulatory function for conidiogenesis in both A. nidulans and F. graminearum among five fluffy gene homologs. flbD deletion abolished conidia and perithecia production, suggesting that FlbD have global roles in hyphal differentiation processes in F. graminearum. We further identified and functionally characterized the ortholog of AbaA, which is involved in differentiation from vegetative hyphae to conidia and known to be absent in F. graminearum [3]. Deletion of abaA did not affect vegetative growth, sexual development, or virulence, but conidium production was completely abolished and thin hyphae grew from abnormally shaped phialides in abaA deletion mutants. Overexpression of abaA resulted in pleiotropic defects such as impaired sexual and asexual development, retarded conidium germination, and reduced trichothecene production. AbaA localized to the nuclei of phialides and terminal cells of mature conidia. Successful interspecies complementation using A. nidulans AbaA and the conserved AbaA-WetA pathway demonstrated that the molecular mechanisms responsible for AbaA activity are conserved in F. graminearum as they are in A. nidulans. F. graminearum ortholog of Aspergillus nidulans wetA has been shown to be involved in conidiogenesis and conidium maturation [4]. Deletion of F. graminearum wetA did not alter mycelial growth, sexual development, or virulence, but the wetA deletion mutants produced longer conidia with fewer septa, and the conidia were sensitive to acute stresses, such as oxidative stress and heat stress. Furthermore, the survival rate of aged conidia from the F. graminearum wetA deletion mutants was reduced. The wetA deletion resulted in vigorous generation of single-celled conidia through autophagy-dependent microcycle conidiation, indicating that WetA functions to maintain conidia dormancy by suppressing microcycle conidiation in F. graminearum. In A. nidulans, FlbB physically interacts with FlbD and FlbE, and the resulting FlbB/FlbE and FlbB/FlbD complexes induce the expression of flbD and brlA, respectively. BrlA is an activator of the AbaA-WetA pathway. AbaA and WetA are required for phialide formation and conidia maturation, respectively [5]. In F. graminearum, the AbaA-WetA pathway is similar to that of A. nidulans, except a brlA ortholog does not exist. Amongst the fluffy genes, only fgflbD has a conserved role for regulation of the AbaA-WetA pathway.

• 한국미생물·생명공학회지
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• 제38권2호
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• pp.129-135
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• 2010

본 논문은 한국인삼의 추출물 제조 시 부수적으로 생산되는 유출액에 의한 환경오염을 방지하고 나아가 이들로부터 고부가가치의 생리활성물질을 유출액에서 생육이 우수한 균류로부터 생산한 논문이다. 유출액에서 생육이 좋았던 Hansenula anomala KCCM 11473으로부터 5'-ribonucleotide 생산 최적 조건은 세포현탁액의 pH를 5.0으로 하고 $55^{\circ}C$에서 24시간 자기소화 시키는 조건이다. 또한 생육이 좋았던 Saccharomyces cerevisiae는 유출액 배지에서 배양 중 약리 성분이 Ginsenoside-Rg3를 고형물 1 g당 0.033 mg을 생성하였다. Mucor miehei KCTC 6011을 유출액에 접종하여 $25^{\circ}C$에서 84시간 배양했을 때 균체 건물 g당 120 mg의 키토산을 생성하였다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 추계학술대회 및 정기총회
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• pp.16-16
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• 2015

Ectomycorrhizal (ECM) mushrooms play a major role in plant growth promotion through symbiotic association with roots of forest trees. They also provide an economically important food resource to us and therefore they have been studied for their artificial cultivation for decades in Korea. We have secured bio-resources of ECM mushrooms from Korean forests and performed their physiological studies. To investigate the cultural characteristics, the fungi were cultured under different conditions (medium, temperature, pH of the medium, inorganic nitrogen source). More than 90% of total 160 strains grew on three solid media (potato dextrose agar, PDA; sabouraud dextrose agar, SDA; modified Melin-Norkrans medium, MMN). The rate of mycelial growth on malt extract agar (MEA) was lower than those of three media (PDA, SDA, MMN). None of the Tricholomataceae strains grew on MEA. Many strains of ECM mushrooms were able to grow at the temperature range of $15{\sim}25^{\circ}C$ on PDA, while they showed poor growth at $10^{\circ}C$ or $30^{\circ}C$. In particular, the growth rates of both Gomphaceae and Tricholomataceae were significantly lower at $10^{\circ}C$ than at $30^{\circ}C$. The optimal pH of many strains was pH 5.0 when they cultured in potato dextrose broth (PDB). Fifty-seven percent of tested strains grew well on medium containing ammonium source than nitrate source. Many strains of Tricholomataceae showed a notable growth on ammonium medium than nitrate medium. Twenty-three percent of strains preferred nitrate source than ammonium source for their mycelial growth. The production and activity of two enzymes (cellulase and laccase) by ECM fungi were also assayed on the enzyme screening media containing CMC or ABTS. Each strains exhibited different levels of enzymatic activities as well as enzyme production. The number of laccase-producing strains was less than that of cellulase-producing strains. We found that 77% of tested strains produced both cellulase and laccase, whereas 2% of strains did not produce any enzymes. The morphological characteristics of mycelial colony were also examined on four different solid media. Yellow was a dominant color in mycelial colony and followed by white and brown on all culture media. ECM mushrooms formed mycelial colonies with a single or multiple colors within a culture medium depending on the strains and culture media. The most common shape of mycelial colony was a circular form on all media tested. Other families except for Amanitaceae formed an irregular colony on MMN than PDA. All strains of Tricholomataceae did not form a filamentous colony on all media. The pigmentation of culture media by mycelial colonies was observed in more than 50% of strains tested on both PDA and SDA. The degree of pigmentation on PDA or SDA was higher than MMN and brown color was dominant than yellow color. The production of exudates from mycelial colony was higher on PDA than MMN. Brown exudates were mainly produced by many strains on PDA or SDA, whereas transparent exudates were mainly produced by strains on MMN. We observed the mycelial colonies with a single or multiple textures in just one culture plate. Wrinkled or uneven colony surfaces were remarkably observed in many strains on PDA or SDA, while an even colony surface was observed in many strains on MMN. Sixty percent of Tricholomaceae strains formed wrinkled surface on PDA. However, they did not form any wrinkle on MMN plate. Cottony texture was observed in mycelia colonies of many strains. Velvety texture was often observed in the mycelial colonies on SDA than PDA and accounted for 60% of Suillaceae strains on SDA.

• KSBB Journal
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• 제22권5호
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• pp.297-304
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• 2007

Lovastatin은 근사형성 균류인 Aspergillus terreus가 생합성하는 이차대사산물로 강력한 고지혈증 치료제로 널리 이용되는 물질이다. 본 연구에서는 lovastatin 고생산변이주를 이용하여 포자배지 최적화를 통한 miniature 배양 방법을 확립하고자 하였다. 우선 miniature 배양에 필수적인 효과적인 포자 형성 방법을 개발하고자 포자 형성 배지의 통계학적 배지 최적화를 수행하였다. Miniature 배양의 inoculum으로 이용되는 대량의 포자를 획득하기 위해 Plackett-Burman 실험법을 이용하여 포자 형성을 향상시키는 성분을 조사한 결과, glucose, sucrose, yeast extract 그리고 $KH_2PO_4$가 주목할 만한 효과를 보였다. 상기 성분의 최적 농도를 확인하기 위해 반응표면분석법 (RSM)을 이용한 결과, PDA 포자 형성 배지와 비교하여 볼 때, 최적 성분 농도에서 포자 형성이 약 190배 증가하였다. 최적화된 포자형성 배지를 이용하여 lovastatin 고생산성 변이주의 대량 선별을 위한 miniature 배양 방법을 확립하기 위해 기존의 실험 과정에 'PaB (adaptation)'라는 한 번의 계대배양을 더 추가한 결과 생산균주의 안정성과 재현성이 큰 폭으로 증가하는 주목할 만한 결과를 얻을 수 있었다. 단기간에 가능한 한 다량의 균주를 스크리닝하기 위해 성장배양과 생산배양 모두 조업부피가 7 ml인 tube를 이용해 miniature 배양을 반복 수행하여, lovastatin 생산성과 배양형태가 훌륭한 변이주를 선별할 수 있었는데, 이 균주는 7 ml tube배양과 250 ml flask배양 (조업부피 50 ml) 모두에서 생산성이 높은 것으로 보아 산소 의존도가 비교적 낮고 생산 안정성이 높은 균주인 것으로 판단되었다. 한편 miniature 배양을 이용해서 lovastatin 고생산성을 보이는 균주를 신속 선별하기 위해서는 균주의 적절한 배양형태 유도가 매우 중요한 것으로 관찰되었다. 즉 생산배양으로의 고활성 균주의 접종을 위해서, 또한 생산배양에서 pellet의 배양형태 유도를 위해서 성장배양 시에는 반드시 고농도의 균사모양을, 생산배양 시에는 직경 1 mm 이하의 pellet모양의 배양 형태를 유지해야만, 생산균주가 lovastatin을 안정적으로 고생산할 수 있는 것으로 관찰되었다. 초기에 선별된 균주를 이용하여 miniature 배양에 의해 고속 균주선별 실험을 반복함으로써 고생산성 균주들을 다량 선별할 수 있었는데, 이들의 lovastatin 생산성을 조사한 결과, 기존의 flask 배양대비 오차범위가 $\pm$20% 이내의 생산성을 보이는 균주가 초기 선별시의 32%에 비해 81%로 크게 증가함을 확인할 수 있었다. 이와 같은 결과는 lovastatin 고생산성, 고안정성 균주의 고속 스크리닝을 위해서 본 연구에서 개발한 tube를 이용한 miniature 배양이 기존의 flask 배양을 대체할 수 있는 훌륭한 배양방법임을 제시해 준다.

• 한국토양비료학회지
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• 제39권4호
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• pp.195-203
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• 2006

길항미생물 MP-1은 여러 종의 곰팡이와 효모 및 음식물을 부패시키는 세균 (그람양성 및 음성) 에 대하여 항균활성을 보였다. MP-1의 16S rRNA gene 염기서열은 기존에 밝혀진 Brukholderia sp.의 염기서열과 99-100% 유사하였다. 배양액으로부터의 항균물질은 에틸아세테이트 (EtOAc)를 사용하여 분리하였으며 EtOAc에 용해된 산성 분획은 silica gel, Sephadex LH-20, ODS 컬럼크로마토 그래피 및 HPLC를 사용하여서 정제를 실시 하였다. 최종적으로 Gas chromatographic-mass 스펙트럼을 통한 분석을 통하여 4 종의 항균 활성을 나타내는 물질은 phenylacetic acid, hydrocinnamic acid, 4-hydroxyphenylacetic acid 및 4-hydroxyphenylacetate methyl ester로 확인 되었다. 각각의 항균 활성물질들의 미생물에 대한 최소저해농도(MIC)는 $250{\sim}2500ug\;ml^{-1}$ 인 것으로 나타났다. 또한 6 mm paper disc 에서의 1mg (건물중) 산성 분획의 항균활성은 같은 비율로 혼합한 표준혼합용액 보다 더 효과적인 것으로 나타났다.

• KSBB Journal
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• 제14권1호
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• pp.36-44
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• 1999

고지혈증 치료제인 Lovastatin을 Aspergillus terreus로부터 생산하기 위해 최적의 탄소원, 질소원, 인산염 및 아미노산을 선정하였다. 단일 탄소원에서는 글리세롤 45mL/L가 Lovastatin 256mg/L로 포도당 45g/L의 기본배지보다 약 3.5배 이상의 높은 Lovastatin 생산량을 나타내었다. 탄소원이 지방산 합성에 이용되는 것을 차단하고 Lovastatin으로의 합성을 촉진하기 위해 기름 증류를 탄소원으로 이용한 결과, 높은 Lovastatin 생산량과 균재량을 나타내었으나, 글리세롤 45mL/L가 Lovastatin 생산량이 낮았다 포도당 50g/L와 글리세롤 50mL/L를 혼합한 복합 탄소원이 Lovastatin 298mg/L로 기본배지에 비해 약 4배 이상의 가장 높은 Lovastatin 생산량을 나타냈었다. 질소원의 영향은 뚜렷하여 질소원에 따라 Lovastatin 생산량이 큰 차이를 나타내었으며, 그 중에서 peptonized milk가 가장 Lovastatin 생산량이 높았다. 인산염 중에서는 $K_2HPO_4$가 가장 높은 Lovastatin 생산량을 나타내었다. 이상에서 얻어진 최적 배지에 각종 아미노산을 첨가한 결과 L-hisbhine과 L-tryptophan이 가장 효과적이었으며, 최적 농도는 둘다 6g/L였다.