• Journal of Microbiology and Biotechnology
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• 제29권2호
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• pp.230-234
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• 2019

Currently, the genetic modification of Aspergillus oryzae is mainly dependent on protoplast-mediated transformation (PMT). In this study, we established a dual selection marker system in an industrial A. oryzae 3.042 strain by using Agrobacterium tumefaciens-mediated transformation (ATMT). We first constructed a uridine/uracil auxotrophic A. oryzae 3.042 strain and a pyrithiamine (PT)-resistance binary vector. Then, we established the ATMT system by using uridine/uracil auxotrophy and PT-resistance genes as selection markers. Finally, a dual selection marker ATMT system was developed. This study demonstrates a useful dual selection marker transformation system for genetic manipulations of A. oryzae 3.042.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 추계학술대회
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• pp.8-8
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• 2019

The stringent response (SR) is characterized as a bacterial defense mechanism in response to various growth-inhibiting stresses. It is activated by accumulation of a small nucleotide regulator, (p)ppGpp, and induces global changes in bacterial transcription and translation. Recent work from our group has shown that (p)ppGpp plays a critical role in virulence and survival in Vibrio cholerae. The genes, relA and relV, are involved in the production of (p)ppGpp, while the spoT gene encodes an enzyme that hydrolyzes it in V. cholerae. A mutant strain defective in (p)ppGpp production (i.e. ${\Delta}relA{\Delta}relV{\Delta}spoT$ mutant) lost the ability to produce cholera toxin (CT) and lost their viability due to uncontrolled production of organic acids, when grown with extra glucose. In contrast, the ${\Delta}relA{\Delta}spoT$ mutant, a (p)ppGpp overproducer strain, produced enhanced level of CT and exhibited better growth in glucose supplemented media via glucose metabolic switch from organic fermentation to acetoin, a neutral fermentation end product, fermentation. These findings indicates that (p)ppGpp, in addition to its well-known role as a SR mediator, positively regulates CT production and maintenance of growth fitness in V. cholerae. This implicates SR as a promising drug target, inhibition of which may possibly downregulate V. cholerae virulence and survival fitness. Therefore, we screened a chemical library and identified a compound that induces medium acidification (termed iMAC) and thereby loss of wild type V. cholerae viability under glucose-rich conditions. Further, we present a potential mechanism by which the compound inhibits (p)ppGpp accumulation. Together, these results indicate that iMAC treatment causes V. cholerae cells to produce significantly less (p)ppGpp, an important regulator of the bacterial virulence and survival response, and further suggesting that it has a therapeutic potential to be developed as a novel antibacterial agent against cholera.

• 한국식품저장유통학회지
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• 제30권1호
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• pp.52-64
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• 2023

100 different yeast colonies were isolated from spontaneously fermented kiwis, persimmons, apples, pears, watermelons, grapes, grape fruits, peachs, and plums, and selected yeast strains were used to produce kiwi-persimmon mixed wine (KPMW). Among the isolates, five representative strains exhibited tolerance to sucrose, alcohol, pH, and potassium metabisulfite when compared with the control yeast strain (Saccharomyces cerevisiae KCCM 12615). All five yeast strains (Y4, Y10, Y28, Y78, and Y81) exhibited 99% 26S rDNA sequence similarity to S. cerevisiae. The pH, acidity, Brix, reducing sugar, alcohol, and organic acid contents were consistent in KPMW prepared from the S. cerevisiae KCCM 12615 and Y28 strains. KPMW made from the Y4, Y10, and Y28 strains exhibited lower quantities of free sugars than those of the KPMW made from the other yeast strains. The level of ethyl esters in KPMW prepared from the Y28 was higher than that in the other KPMWs. All strains, except for Y28, produced lower concentrations of sulfur and ketone compounds. Furthermore, the KPMW produced by the Y28 strains had total phenolic contents with 1.1 g/L, with DPPH and ABTS radical scavenging activities of 57.06% and 55.62%, respectively, and a FRAP assay value of 0.72. Our results suggest that Y28 is a promising yeast strain for producing high-quality wines.

• 한국식품과학회지
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• 제14권1호
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• pp.72-79
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• 1982

Aspergillus niger CF를 최초(最初)의 균주(菌株)로 하고 이것에 자외선조사처리(紫外線照射處理)를 하여 돌연변이균주(變異菌株) Asp. niger CF-11을 얻었으며 이어서 NTG 처리(處理)에 의(依)하여 Asp. neger CF-11 균주(菌株)에서 변이균주(變異菌株) Asp. niger CF-22 및 CF-21를 분리(分離)하였다. 변이균주(變異菌株)의 특징(特徵)을 조사(調査)하고 밀기울국(麴) 및 밀가루국(麴)에서의 효소생산(酵素生産) 및 산생성(酸生成)을 검토(檢討)한 결과(結果)는 아래와 같다. 1. Asp. niger CF-22 변이균주(變異菌株)는 포자두(胞子頭)의 색(色)이 변(變)한 tan type의 균주(菌株)였으며 CF-22는 최초(最初)의 친주(親株) CF에 비(比)하여 밀기울국배양(麴培養)의 최적조건(最適條件)에서 글루코아밀라아제활성(活性)이 약(約) 2배(倍), ${\alpha}-$아밀라아제활성(活性)은 약(約) 50% 증가(增加)되었다. 2. Asp. niger CF-21 변이균주(變異菌株)는 포자두(胞子頭)의 색(色)은 변(變)하지 않았으나 밀기울국(麴)에서 생육(生育)과 포자착성(胞子着性)이 최초(最初)의 친주(親株) CF보다 늦었다. 이 변이균주(變異菌株)의 산생성력(酸生成力)은 최초(最初)의 친주(親株)보다 약(約) 4배(倍) 많았다. 3. Asp. niger CF-22 변이균주(變異菌株) 및 CF-21 변이균주(變異菌株)는 최초(最初)의 친주(親株)보다 클루코아밀라아제 및 ${\alpha}-$아밀라아제활성(活性)은 증강(增强)되었으나 단백질 가수분해효소의 활성(活性)은 오히려 떨어졌다. 4. 밀기울국(麴)에서 Asp. niger CF-22 변이균주(變異菌株)의 글루코아밀아제 생성(生成)의 최적조건(最適條件)은 $30{\sim}35^{\circ}C$에서 $2{\sim}3$일간(日間)이었으며 ${\alpha}-$아밀라아제의 경우는 $30{\sim}35^{\circ}C$에서 2일간(日間)이었다. 5. Asp. neger CF-21 변이균주(變異菌株)의 산생성력(酸生成力)은 밀기울국(麴)에서 $30^{\circ}C$로 2일후(日後)에 최고(最高)에 달(達)하였으며 밀가루국(麴)에서는 $30^{\circ}C$로 3일후(日後)에 최고(最高)값을 나타내었다. 최적조건(最適條件)에서의 산생성력(酸生成力)은 밀기울국(麴)과 밀가루국(麴) 사이에 차(差)가 별(別)로 없었다.

• 생명과학회지
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• 제32권3호
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• pp.202-209
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• 2022

반수체 단세포 진핵생물인 녹조류 Chlamydomonas reinhardtii는 미세조류와 유전자 변형을 이용하여 고부가가치 물질을 생산하는 세포 공장으로 연구자와 산업계에서 오랫동안 사용되어 왔다. 현재 대부분의 기초 및 산업 연구에 사용되는 외래종인 C. reinhardtii를 대체하기 위하여 충청과 전라지역 12개의 담수에서 채취한 시료에서 Chlamydomonas로 추정되는 미세조류 K01을 분리하였다. 분리균주 K01의 형태학적 분석과 18S rDNA 유전자 서열(NCBI 수탁번호 KC166137)의 계통발생학적 분석을 통하여 분리균주 K01는 Chlamydomonas reinhardtii로 동정 되었다. 분리균주 C. reinhardtii K01의 성장 및 지질 함량은 TAP 배지에서 3개의 야생 균주 및 4개의 돌연변이 균주와 비교하였다. 이들 균주 중 C. reinhardtii K01 균주가 배양 3일째 1.74×10⁷ cells/ml개의 세포수가 관찰되었다. 이는 비교 균주 중 가장 높은 세포 수(1.20×10⁷ cells/ml)를 나타내어 UTEX2244와 비교했을 때 1.5배 빠른 성장속도를 보였다. 분리균주 C. reinhardtii K01의 지질함량(20.67%)은 야생형 균주의 지질함량과 유사하였다. 분리균주 Chlamydomonas reinhardtii K01의 지방산 성분은 7종의 분양 균주에서 확인된 지방산 중 oleate (C18:1)가 검출되지 않았다. 분리균주 C. reinhardtii K01은 nitrate (NaNO₃)를 질소원으로 포함하는 BG11배지에서 배양 6일 동안 0.87 g/l까지 세포밀도가 증가하였으나, 분양균주인 7종의 Chlamydomonas의 경우 모든 균주에서 세포증식이 거의 일어나지 않았다.

• Journal of Microbiology
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• 제44권5호
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• pp.556-561
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• 2006

A differential display for the expression profiles of wild-type Cryphonectria parasitica and its virally-infected isogenic hypovirulent strain revealed several transcripts of interest, which evidenced significant matches with fungal genes of known function. Among which, we have further analyzed an amplified PCR product with significant sequence similarity to the known fungal stress-responsive thioredoxin gene from Neurospora crassa. The product of the cloned thioredoxin gene, CpTrx1, consists of 117 amino acids, with a predicted molecular mass of 13.0 kDa and a pI of 5.4. Sequence comparisons demonstrated that the deduced protein sequence of the CpTrx1 gene evidenced a high degree of homology to all known thioredoxins, with the highest degree of homology with trx1, a thioredoxin gene from Saccharomyces cerevisiae, and evidenced a preservation of the conserved hall markresidues (Trp-Cys-Gly-Pro-Cys) at the active site of thioredoxin. The E. coli-generated CpTRX1 manifested thioredoxin activity, according to the insulin reduction assay, which indicates that the cloned gene does indeed encode for the C. parasitica thioredoxin.

• Molecules and Cells
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• 제28권3호
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• pp.209-213
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• 2009

Caenorhabditis elegans is a free living soil nematode and thus in its natural habitat, C. elegans encounters many different species of soil bacteria. Although some soil bacteria may be excellent sources of nutrition for the worm, others may be pathogenic. Thus, we undertook a study to understand how C. elegans can identify their preferred food using a simple behavioral assay. We found that there are various species of soil bacteria that C. elegans prefers in comparison to the standard laboratory E. coli strain OP50. In particular, two bacterial strains, Bacillus mycoides and Bacillus soli, were preferred strains. Interestingly, the sole feeding of these bacteria to wild type animals results in extended lifespan through the activation of the autophagic process. Further studies will be required to understand the precise mechanism controlling the behavior of identification and selection of food in C. elegans.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 춘계학술대회 및 임시총회
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• pp.20-20
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• 2015

Endophytic fungi are microorganisms inhabiting living plant tissues without causing apparent harm to the host. They are drawing increasing attention due to their ability to produce various bioactive compounds as well as their effects on host growth and resistance to biotic and abiotic stresses. As a first step to assess biodiversity of plant associated fungi in Korea and the following evaluation on diverse biological activities, we are collecting endophytic fungi from plant in wild followed by systematic long-term storage in liquid nitrogen. Molecular identification using ITS sequences was also incorporated for pure culture by hyphal tip isolation. As of April 2015, about 1,400 fungal strains had been isolated from about 170 plant taxa. Fungal isolates belonging to Pleosporales, Diaporthales, Glomerellales, Hypocreales, and Xylariales were the most abundant. These collections are being used for several complementary researches, including screening of isolates with novel bioactive compounds or conferring drought stress resistance, phylogenetic and genomic study. Genome sequencing was performed for 3 isolates, one Xylaria sp. strain JS573 producing griseofulvin, an antifungal compound, and two Fusarium spp. strains JS626 and JS1030, which are assumed to be new species found in Korea. More detailed analysis on these genomes will be presented. These collections and genome informations will serve as invaluable resources for identifying novel bioactive materials in addition to expand our knowledge on fungal biodiversity.

• Asian-Australasian Journal of Animal Sciences
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• 제9권6호
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• pp.679-684
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• 1996

This study evaluates the susceptibility of scaleless mutant chickens to very virulent Marek's disease virus (vvMDV) inoculation. One day old chickens were inoculated subcutaneously with Taiwanese isolates of LTB-1 and LTS-1 strains, and standard strain of Md/5. Compared with the non-inoculated group the vvMDV-inoculated chickens showed decreased body weights and atrophy of lymphoid organs before 35 days old. These results indicate that scaleless chickens show the same susceptibility as the wild type chickens to vvMDV infection. Furthermore, the protective effect of herpesvirus of turkey (HVT) vaccination at 1 day old against vvMDV challenge was evaluated. Scaleless mutant chickens of treated groups showed 20-30% early death, and 85.7-100% and 12.5-14.2% had lymphomatous lesions in visceral organs and peripheral nerves, respectively. No significant lesions were observed in non-challenged chickens of the control group. The HVT vaccination did not provide an effective protection against vvMDV infection. It is concluded that scaleless mutant chickens are susceptible to vvMDV infection.

• Mycobiology
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• 제46권2호
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• pp.114-121
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• 2018

Mon1 is a guanine nucleotide exchange factor subunit that activates the Ypt7 Rab GTPase and is essential for vacuole trafficking and autophagy in eukaryotic organisms. Here, we identified and characterized the function of Mon1, an ortholog of Saccharomyces cerevisiae Mon1, in a human fungal pathogen, Cryptococcus neoformans. Mutation in mon1 resulted in hypersensitivity to thermal stress. The mon1 deletion mutant exhibited increased sensitivity to cell wall and endoplasmic reticulum stress. However, the mon1 deletion mutant showed more resistance to the antifungal agent fluconazole. In vivo studies demonstrated that compared to the wild-type strain, the mon1 deletion mutant attenuated virulence in the Galleria mellonella insect model. Moreover, the mon1 deletion mutant was avirulent in the murine inhalation model. These results demonstrate that Mon1 plays a crucial role in stress survival and pathogenicity in C. neoformans.