• 한국미생물·생명공학회지
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• 제18권6호
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• pp.653-659
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• 1990

Schwanniomyces castelli CBS 2863의 glucoamylase 유전자를 Saccharomyuces cerevisiae에 cloning하고 발현시켰다. Southern blot 분석결과, 형질전환체의 glucoamylase 유전자는 Sch. castellii genomic DNA로부터 나온 것임을 확인하였고 5.1 혹은 1.3kb의 Sch.castellii 유전자에 해당되는 DNA 절편이 S.cerevisiae 에서 관찰되지는 않았다. S.cerevisiae의 형질전환체의 glucoamylase 활성은 Sch. castellii의 그것에 비해 2,000배 정도 낮았고 E.coli에서는 발현되지 않았다. Sch.castellii의 glucoamylase와 동일한 특성과 분자량을 가지고 있음을 알 수 있었다.

• 미생물학회지
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• 제32권1호
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• pp.34-39
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• 1994

Schwanniomyces castellii의 제놈 DNA로 제조된 유전자 은행으로부터 cloning된 ${\alpha}$-amylase 유전자가 Sacchromyces cerevisiae에서 발현되었다. Cloning된 삽입 DNA 절편의 크기는 약 5.0 kb이었고, Southern 및 immunoblot 분석 결과 cloning된 ${\alpha}$-amylase 유전자가 Sch. Castellii로부터 유래되었음이 확인되었다. S. cerevisiae SHY3 형질전환체에서 Sch. Castellii ${\alpha}$-amylase 유전자발현은 모균주에 비해 낮았으나, 단백질의 분자량 및 효소의 성질은 Sch. Castellii에서 분리한 ${\alpha}$-amylase의 그것과 차이가 없었다.

• 한국미생물·생명공학회지
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• 제21권6호
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• pp.534-541
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• 1993

The relationship between Schwanniomyces occidentalis CBS 2863 (formerly castellii) and CBS 1153 (formerly alluvius), and their variety persoonii was examined at alpha-amylase gene level. Using Sch. occidentalis alpha-amylase gene as probe, Sch. occidentalis alpha-amylase gene homologues were obtained from Sch. occidentalis CBS 1153 and Sch. occidentalis var. persoonii. The restriction analysis of these homologues showed that the restriction enzyme sites between Sch. occidentalis CBS 2863 and CBS 1153 was identical but different between these strains and Sch. occidentalis var. persoonii.

• KSBB Journal
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• 제7권3호
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• pp.229-234
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• 1992

Schwanniomyces castellii NRRL Y-2477에 의한 전분의 직접 알콜발효에 대한 연구를 수행하였다. 이 균주의 150g/l glucose에 대한 알콜발효능력은 사용기질의 94%를 이용하여 ethanol를 63.9g/l를 생성하였으며, 이때의 ethanol yeild를 0.45g-ethanol/g-glucose로서 일반적인 알콜발효 효모인 Sacch. cerevisiae보다는 약간 낮았다. 전분이 상온에서 최대로 용해될 수 있는 20g/l전분의 직접알콜 발효에서는 통기인 경우 ethanol의 생성없이 세포성장만이 이루어졌으며, 통기를 하지 않은 경우는 9.1g/l의 ethanol를 생성하여 ethanol yeild는 이론값의 88%를 나타내었다. 반면 100g/l의 dextrin을 이용한 알콜발효에서는 통기에 의하여 ethanol의 생성이 1.8배 증가하였으며, 또한 $CaCO_3$첨가에 의한 pH를 조절한 경우 조절하지 않은 경우보다 ethanol생성이 2.1배 증가한 34.5g/l의 농도로서 이때의 기질에 대한 발효능력은 82%이고 ethanol yeild는 이론값의 약 84%였다. 또한 150g/l dextrin의 알콜발효에서는 약 79%의 기질을 소모하면서 52.1g/l의 ethanol을 생성하였다. 따라서 Schwanniomyces castellii NRRL Y-2477 에 의한 전분의 직접 알콜발효에서의 율속단계는 전분의 가수분해 과정임을 확인하였다.

• 미생물학회지
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• 제29권2호
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• pp.104-110
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• 1991

The glucoamylase of Schwanniomyces castellii was purified to homogeneity from the culture filtrate. the purified enzyme was a glycoprotein with a molecular mass of about 145 KDa, which was monomeric protein with an isoelectric point of 4.3. The pH and temperature optima were 5.5 and 40.deg.C, respectively. The enzyme was fairly stable up to 50.deg.C and at acid pH range (pH 4.5-6.0). The apparent Km of the enzyme toward soluble starch, isomaltose and pullulan were 3.84, 0.51 and 13.7 mg/ml, respectively. The analysis of amino acid composition on this enzyme was found to be acidic protein like other fungal glucoamylase. The amino acid sequence of N-terminal peptide consisted of Ala-Pro-Ala-Asp-Gly-Ile-Gly-Asp-X-Ala-X-Ala.

• Journal of Microbiology and Biotechnology
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• 제8권6호
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• pp.625-630
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• 1998

Using a modified yeast secretory expression vector, $\alpha$-amylase of Schwanniomyces occidentalis was produced from Saccharomyces cerevisiae. The expression vector contains the a-amylase gene (AMY) harboring its own promoter without the regulatory region and the adenine base at the -3 position from the ATG start codon, its own signal sequence, CYC1 transcription terminator, and SV40 enhancer. The expressed $\alpha$-amylase activity from cells carrying the plasmid was approximately 26 times higher than that from the cells harboring an unmodified plasmid. When Saccharomyces diastaticus was transformed with this modified vector, a 2.5 times higher level of amylolytic activity than that from Sch. occidentalis was observed.

• Journal of Microbiology and Biotechnology
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• 제3권2호
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• pp.95-98
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• 1993

This study was carried out to isolate and characterize the mutant strains of Schwanniomyces castellii NRRL Y-2477. Mutants were prepared with the treatment of ethyl methane sulfonate. 2-deoxy-D-glucose resistant mutants were isolated and two mutants were selected based on their high production of amylolytic enzymes and their ability to ferment starch. The mutants selected had higher a-amylase and glucoamylase activities than the wild type strain from several other carbon sources. Especially, it was revealed that mutant strain M-9, when cultured in the presence of glucose as a sole carbon source, shows relatively high activities of a-amylase and glucoamylase compared to those of the wild type strain. In result, this mutant strain can be considered as a constitutive producer of amylolytic enzymes. To compare the ethanol production ability of wild type strain and of mutant strains selected, an alcohol fermentation was carried out using 100 g/l soluble starch. Mutant strain M-9 did not improve the direct alcohol fermentation of starch, despite its excellent amylolytic activities performance. On the other hand, mutant strain M-6 produced 37.9 g/l (4.8%, v/v) ethanol by utilizing about 82% of substrate.

• 한국미생물·생명공학회지
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• 제21권6호
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• pp.582-587
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• 1993

The extracellular alpha-amylase was purified to homogenity from the culture filtrate of starch grown Sch. castellii CBS 2863. The purified enzyme was glycoprotein with a molecular weight of about 56 kDa. The pH and temperature optimum were 5.5 and 40C, respectively. The enzyme was fairly stable up to 40C and at acid pH range (pH 4.0-7.0). The apparent Km and Vmax of the enzyme toward starch was 1.0mg/ml and 100U/mg protein, respectively. The analysis of amino acid composition was found to be acidic protein. The amino acid sequence of N-terminal peptide consisted of Asp-Val-Ser-Ser-Ala-X-X-Thr-Arg-Ser-Glu-Ser-Ile-Tyr.

• Journal of Microbiology and Biotechnology
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• 제1권3호
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• pp.212-219
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• 1991

Four species of yeast, Saccharomyces cerevisiae, Candida utilis, Saccharomycopsis flbuligera, and Schwanniomyces castellii were evaluated for their ability to bioconvert potato processing waste water into microbial protein and the resulting single-cell proteins were evaluated as protein sources for rainbow trout, using in vitro analyses. The studies indicated that Schwanniomyces castellii, which utilizes starch dircetly and converts it into cell mass efficiently, was suitable for the bioconversion. In the single-stage continuous bioconversion, the yield S. castellii cell mass, which contained approximately 37% protein, was 77%, at dilution rate 0.25 $h^{-1}$. Reduction of total carbohydrate was 81%. During batch fermentations, cell mass yield was about 72% and total carbohydrate reduction was 81%. Among the yeasts tested, S. castellii possessed the most fragile cell wall and had a favorable amino acid profile for salmonid fish; protein score of 86% (Met). In an in vitro pepsin digestibility test 80% digestibility (23~38% above control) was observed when cells were pre-heated in a steam bath for 30 min. Results presented should be regarded as being preliminary in nature because they were derived from single experiments.

• Journal of Microbiology and Biotechnology
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• 제9권5호
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• pp.668-671
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• 1999

The gene encoding Schwanniomyces occidentalis $\alpha-amylase$(AMY) was introduced into Saccharomyces cerevisiae var. diastaticus which secreted only glucoamylase, by using a linearized yeast integrating vector to develop stable strains with a capability of secreting $\alpha-amylase$and glucoamylase simultaneously. A dominant selectable marker, the geneticin(G418) resistance gene (Gt^r$), was cloned into a vector to screen wild-type diploid transformants harboring the AMY gene. The amylolytic activities of transformants were about 3-7 times higher than those of the recipient strains. When grown in nonselective media, the transformants with the linearized integrating vector containing the AMY gene exhibited almost all of the mitotic stability after 100 generations.