• Journal of Microbiology and Biotechnology
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• 제26권11호
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• pp.1891-1907
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• 2016

Yeasts that are present in marine environments have evolved to survive hostile environments that are characterized by high exogenous salt content, high concentrations of inhibitory compounds, and low soluble carbon and nitrogen levels. Therefore, yeasts isolated from marine environments could have interesting characteristics for industrial applications. However, the application of marine yeast in research or industry is currently very limited owing to the lack of a suitable isolation method. Current methods for isolation suffer from fungal interference and/or low number of yeast isolates. In this paper, an efficient and non-laborious isolation method has been developed and successfully isolated large numbers of yeasts without bacterial or fungal growth. The new method includes a three-cycle enrichment step followed by an isolation step and a confirmation step. Using this method, 116 marine yeast strains were isolated from 14 marine samples collected in the UK, Egypt, and the USA. These strains were further evaluated for the utilization of fermentable sugars (glucose, xylose, mannitol, and galactose) using a phenotypic microarray assay. Seventeen strains with higher sugar utilization capacity than the reference terrestrial yeast Saccharomyces cerevisiae NCYC 2592 were selected for identification by sequencing of the ITS and D1/D2 domains. These strains belonged to six species: S. cerevisiae, Candida tropicalis, Candida viswanathii, Wickerhamomyces anomalus, Candida glabrata, and Pichia kudriavzevii. The ability of these strains for improved sugar utilization using seawater-based media was confirmed and, therefore, they could potentially be utilized in fermentations using marine biomass in seawater media, particularly for the production of bioethanol and other biochemical products.

• 한국환경농학회지
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• 제35권2호
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• pp.137-142
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• 2016

BACKGROUND: Identification of endophytic yeasts inhabiting the internal roots of the Mankyua chejuense tree requires techniques involving biotechnology. There is a need for a culture-based method to isolate and identify yeast strains associated with M. chejuense.METHODS AND RESULTS: We spread homogenized M. chejuense root samples onto glucose-peptone- yeast agar containing antibiotics, Triton X-100, and L-sorbose. A total of 152 yeast isolates were obtained and identified via phylogenetic analysis based on ITS gene sequencing. The results revealed that the root-associated yeast species included the genera Cyberlindnera (140 isolates), Candida (11 isolates), and Kluyveromyces (one isolate). Additionally, three yeast isolates showed high bioethanol production.CONCLUSION: We identified the specific yeast community associated with M. chejuense roots. These yeast isolates may have industrial applications as bioethanol producers. Our findings revealed that Cyberlindnera isolates included C. suaverolens and C. satumus, while Kluyveromyces isolates showed high bioethanol production.

• 한국수산과학회지
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• 제32권3호
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• pp.280-283
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• 1999

고밀도 배양에 있어서 먹이종류 (해수 Chlorella, 담수 Chlorella, 유지효모)에 따른 Rotifer, Brachionus rotundiformis 성장과 영양가를 조사하기 위해서 10$\ell$ 배양수조에서 실험을 실시하였다. 해수 Chlorella, 담수 Chlorella와 유지효모를 공급한 rotifer의 최고밀도는 각각 10,900$\~$12,400개체/ml, 9,190$\~$10,600개체/ml, 2,390$\~$2,750개체/ml, 였다. 따라서 해수 Chlorella, 담수 Chlorella를 공급한 rotifer의 최고밀도는 유지효모를 공급한 rotifer보다 높게 나타났다. 또한 해수 Chlorella를 공급한 rotifer의 고도불포화지방산 함량은 $8.71\%$로 나타났다. 이 것은 유지효모를 공급한 rotifer ($9.14\%$)와 비슷한 경향을 보였지만, 담수 Chlorella를 공급한 rotifer ($4.45\%$)보다는 높게 나타났다. 따라서 본 연구의 결과를 종합해 보면 고밀도 rotifer 배양에 있어서 양질의 rotifer를 생산하기 위해서 해수 Chlorella가 적절한 먹이인 것을 판단된다.

• Mycobiology
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• 제48권3호
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• pp.195-203
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• 2020

Marine yeasts have tremendous potential in industrial applications but have received less attention than terrestrial yeasts and marine filamentous fungi. In this study, we have screened marine yeasts for amylolytic activity and identified an amylase-producing strain PH-Gra1 isolated from sea algae. PH-Gra1 formed as a coral-red colony on yeast-peptone-dextrose (YPD) agar; the maximum radial growth was observed at 22 ℃, pH 6.5 without addition of NaCl to the media. Based on the morphology and phylogenetic analyses derived from sequences of internal transcribed spacer (ITS) and a D1/D2 domain of large subunit of ribosomal DNA, PH-Gra1 was designated Sporidiobolus pararoseus. S. pararoseus is frequently isolated from marine environments and known to produce lipids, carotenoids, and several enzymes. However, its amylolytic activity, particularly the optimum conditions for enzyme activity and stability, has not been previously characterized in detail. The extracellular crude enzyme of PH-Gra1 displayed its maximum amylolytic activity at 55 ℃, pH 6.5, and 0%-3.0% (w/v) NaCl under the tested conditions, and the activity increased with time over the 180-min incubation period. In addition, the crude enzyme hydrolyzed potato starch more actively than corn and wheat starch, and was stable at temperatures ranging from 15 ℃ to 45 ℃ for 2 h. This report provides a basis for additional studies of marine yeasts that will facilitate industrial applications.

• 한국환경농학회지
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• 제32권3호
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• pp.240-243
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• 2013

효모의 유용 기능을 탐색하기 위해서는 효모만을 스크리닝 하는 방법의 정립이 요구되는데 이를 위해서 알로에에 정착하는 효모 군집을 분석하였다. 본 연구에서는 알로에 베라(Aloe vera)와 알로에 사포나리아 (Aloe saponaria)의 잎을 파쇄하여 세균을 억제하기 위해서 항생제 chloramphenicol과 streptomycin과 곰팡이 생장을 억제하기 위해서 Triton X-100과 L-sorbose를 포함한 4가지 선택 배지(DOB with CS, GPY, YM, SCG)에 도말 하였고, A. vera에서 총 67균주, A. saponaria에서 총 42균주를 분리해 내었다. 분리된 균주를 ITS 1, 4 primer를 사용하여 sequence의 계통분석을 실시한 결과, A. vera에서는 Meyerozyma 가 56균주, Rhodotorula 가 1균주, Sporobolomyces 가 1균주, Cryptococcus 가 9균주, A. saponaria에서는 Rhodosporidium 가 41균주, Sporobolomyces가 1균주로 분포 되었다. 계통분석한 모든 분리 균주가 효모로 밝혀졌으며, 특히 대형 플레이트를 도입하여 신속하고 간편하게 대량의 효모를 발굴할 수 있음을 보였다.

• Journal of Microbiology and Biotechnology
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• 제18권9호
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• pp.1522-1528
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• 2008

The morphogenetic behavior of a tropical marine Yarrowia lipolytica strain on hydrophobic substrates was studied. Media containing coconut oil or palm kernel oil (rich in lauric and myristic acids) prepared in distilled water or seawater at a neutral pH supported 95% of the cells to undergo a transition from the yeast form to the mycelium form. With potassium laurate, 51 % of the cells were in the mycelium form, whereas with myristate, 32% were in the mycelium form. However, combinations of these two fatty acids in proportions that are present in coconut oil or palm kernel oil enhanced the mycelium formation to 65%. The culture also produced extracellular lipases during the morphogenetic change. The yeast cells were found to attach to the large droplets of the hydrophobic substrates during the transition, while the mycelia were associated with the aqueous phase. The alkane-grown yeast partitioned more efficiently in the hydrophobic phases when compared with the coconut oil-grown mycelia. A fatty acid analysis of the mycelial form revealed the presence of lauric acid in addition to the long-chain saturated and unsaturated fatty acids observed in the yeast form. The mycelia underwent a rapid transition to the yeast form with n-dodecane, a medium-chain aliphatic hydrocarbon. Thus, the fungus displayed a differential behavior towards the two types of saturated hydrophobic substrates.

• Fisheries and Aquatic Sciences
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• 제8권4호
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• pp.235-242
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• 2005

Baker's yeast, Saccharomyces cerevisiae, has been widely used as a food organism for rotifers used in the larval production of marine fish. However, the nutritional value of the yeast is relatively poor compared with that of the marine alga Chlorella. We examined the nutritional value of another yeast, Candida utilis, and whether its food value could be increased through manipulation such as a cell wall treatment. Candida utilis and S. cerevisiae and their manipulated varieties were assessed with regard to the growth and nutrition of the rotifer Brachianus plicatilis. Larvae of the flounder Paralichthys alivaceus were cultured with rotifers fed on the yeast species, and the dietary value of the rotifers for the larvae was examined. Rotifers that were fed C. utilis grew faster than those provided with S. cerevisiae. Rotifers grew slightly faster on manipulated yeast than on non-manipulated yeast varieties. Of the two yeast species, C. utilis had better dietary value for rotifers. Flounder larvae cultured with rotifers that had fed on C. utilis displayed better growth and survival ($\%$) than did those cultured with rotifers that had fed on S. cerevisiae. Although the manipulated variety of C. utilis was better than the non-manipulated variety in terms of rotifer growth, the flounder larvae survived ($\%$) and grew better when they were fed rotifers that had eaten non-manipulated C. utilis. However, the nutritional value of this yeast species was still lower than that of Chlorella.

• 한국환경농학회지
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• 제34권3호
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• pp.238-243
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• 2015

BACKGROUND: Yeasts associated with fleabane flowers were identified using isolation methods previously applied in yeast biotechnology. A culture-based approach was required for isolation of many yeast strains associated with fleabane. METHODS AND RESULTS: We spread homogenized fleabane flowers onto GPY medium containing chloramphenicol, streptomycin, Triton X-100, and L-sorbose. We isolated 79 yeast strains from the flowers of wild fleabane, and identified the yeasts via phylogenetic analysis of isolates from agar plates. The yeast species included 39 isolates of Aureobasidium pullulans, 17 of the genus Candida, 14 of the genus Rhodosporidium, 6 of the genus Cryptococcus, and 3 of the genus Rhodotorula. CONCLUSION: Yeast isolates associated with fleabane flowers included A. pullulans (39 isolates) and other yeast species (40 isolates). Such yeast isolates may have biotechnological potential.

• 한국수산과학회지
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• 제37권1호
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• pp.7-12
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• 2004

This study investigated the possibility of salinity acclimation of freshwater rotifers (Brachionus calyciflorus) as live food for sweetfish (Plecoglossus altivelis) larvae, and also examined the optimal salinity for the growth of sweetfish. Freshwater rotifers cultured in 0 and 4 PSU and seawater rotifers (B. rotundiformis) cultured in 33 PSU were supplied to the larvae with four kinds of enrichment material (condensed freshwater Chlorella, $\omega-yeast,$ baker's yeast, Super Selco) and larval growth at 4 PSU was examined. Growth of the freshwater rotifers positively increased from 0 PSU to 6 PSU, but decreased when over 8 PSU was reached. Growth and survival of the sweet fish larvae reared in 0 PSU were significantly lower than those reared in either 4 PSU or 33 PSU. This indicated that the freshwater rotifers (B. calyciflorus) could be used as live food for sweetfish larvae reared in 4 PSU. The body weight of sweetfish larvae fed on freshwater rotifers enriched with Super Selco was the highest at 0.163 mg, but there was no significant difference in survival and body length of the fish fed with the other enrichment materials. The content of n-3 HUFA of the sweetfish larvae fed on the freshwater rotifers enriched with Super Selco and the condensed freshwater Chlorella was higher than that enriched with $\omega-yeast$ and baker's yeast. These results indicated that B. calyciflorus cultured with the condensed freshwater Chlorella could be used for the sweetfish larvae without enrichment, and the most efficient enrichment material for B. calyciflorus is Super Selco.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.5412-5418
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• 2014

참돔 이리도바이러스(RSIV)는 이리도바이러스과에 속하며, 많은 아시아 국가에서 감염성 어류 질병을 유발하여 양식산업에 커다란 경제적 손실을 입히는 바이러스이다. 우리는 최근에 효모표면발현(yeast surface display, YSD)를 사용하여 다양한 해양바이러스를 동정하고 검출할 수 있는 새로운 실험시스템을 개발하였다. 이 연구에서 우리는 참돔 이리도 바이러스(RSIV)의 외피단백질을 효모표면 발현 기법을 이용하여 발현시켰다. 바이러스 외피단백질 유전자는 염기서열 데이터베이스에 기초하여 합성되었고, 효모발현벡터인 pCTCON2으로 서브클로닝되었다. 이 벡터는 효모 strain EBY100으로 형질전환 되었다. Flow cytometry와 Western blot analysis를 통해 RSIV 외피단백질의 발현을 확인하였다. ${\beta}$-mercaptoethanol 처리에 의해 발현된 바이러스 외피단백질을 효모 표면로부터 분리하였다. 이 연구의 결과는 YSD 시스템이 해양바이러스 외피단백질을 획득하기 위한 매우 좋은 발현시스템이라는 것을 보여준다.