• Current Research on Agriculture and Life Sciences
• /
• 제30권1호
• /
• pp.1-11
• /
• 2012

We identified cdf based on screening of the Arabidopsis cDNA library for functional suppressors of the AtBI-1 (a gene described to suppress the cell death induced by Bax gene expression in yeast). The cdf was located on Chr. V and was composed of 5 exons and 4 introns. It encodes a protein of 258 amino acid residues with a molecular weight of 28.8 kDa. The protein has 3 transmembrane domains in the C-terminal region. The cdf has one homologue, named cdf2, which was found in Arabidopsis. Like cdf, cdf2 also induced growth defect in yeast. The effect of the cell growth defect factor was somewhat lower than Bax. cdf could arrest the growth of yeast. Its localization to the nucleus was essential for the suppression of yeast cell proliferation. Morphological abnormality of intracellular network, which is a hallmark of AtBI-1, was attenuated by expression of cdf.

• 한국미생물·생명공학회지
• /
• 제14권6호
• /
• pp.467-471
• /
• 1986

Fusarium moniliforme으로부터 순모세포벽 분해효소를 생산하고 분리, 정제하여 효소특성 및 protoplast 제조실험을 하였다. Ammonium nitrate를 0.2％ 첨가한 Baker's yeast 배지에서 7일간 진탕배양으로 효소를 생산한 후 Ammonium sulfate로 분획하고 Sephadex(G-100) column chromatography하여 세개의 peak를 얻었다 첫 번째 peak는 proteolytic, lytic activity 및 laminarin 분해력가를 보였으며, 두 번째 Peak는 lytic activity와 laminarin 분해력가를 동시에 가지고 있었으며, 세 번째 peak는 lytic activity만을 가지고 있었다. 분리된 세개의 peak를 혼합하였을때 개개의 peak보다 훨씬 높은 역가을 나타내어 상승효과를 보였고 또한 환원제에 의한 효소력가의 상승효과도 있었다. protoplast 수율은 99.2％정도였다

• 한국미생물·생명공학회지
• /
• 제21권3호
• /
• pp.276-280
• /
• 1993

Cell lytic enzyme, 5'-phosphodiesterase, and AMP-deaminase were used to produce yeast extract as a natural seasoning from beer yeast cells. Prior to the addition of cell lytic enzyme, heat treatment was performed to increase the cell wall degradation` the optimum condition of the cell lytic enzyme was 50C at pH 7.0. The production yields by the enzymatic method and conventional autolysis method were 42% and 35%, respectively. The total quantity of 5'-nucleotides, GMP and IMP, produced by enzymatic method was increased by 45% than that by the conventional method. Futhermore, the operation time of enzymatic method was only 6.5 hrs, significantly reduced from 24 hrs of the conventional method.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1994년도 추계 총회 및 학술발표회
• /
• pp.1-6
• /
• 1994

Many useful biomaterials like enzymes are contained in yeast cells. However, the release of these intracellular biomateriais from the cells is required to recover them with hot water, solvent or various cell breakage methods of mechanical or non mechanical ones. The cell lysis or breakage of yeast is usually made by solvent like ethyl acetate and mechanical disintrgration with high pressure homogenizer or agitating beads mill. The separation of cell debris (i.e. solid liquid separation) is done by centrifuge or membrane depending on the recovery conditions. The features of both separation methods are shown in Tables 1 and 2. As it is often difficult to obtain a clear supernatant by centrifuge from the suspension containing cell debris, the membrane separation is also often used to gel a clear supernatant. In this report we introduce the several applications of membrane separation to separate the cell debris of yeast disintegrated chemically or mechanically and to recover the intracellular biomaterials.

• Animal cells and systems
• /
• 제6권4호
• /
• pp.335-339
• /
• 2002

Mouse T cells overexpressing the SRG3 protein displayed morphological changes; the cells were enlarged and their shapes were irregular compared to the normal parental cells. In addition, growth rate of the cells was dramatically reduced and their DNA contents were increased. The increased DNA contents were due to an increase in number of chromosomes in these cells. We have observed similar results in S. cerevisiae cells overex-pressing the yeast SWI3 protein. Yeast cells overexpressing SWI3 protein These results suggest that the SRG3/SWI3 protein plays an important role in cell growth and cell cycle progression.

• 한국미생물·생명공학회지
• /
• 제36권4호
• /
• pp.307-313
• /
• 2008

Bacillus sp. endoxylanase 유전자(xynB, 642 bp)의 효모 표면발현계 pCTXYN(6.8 kb)를 구축하고 Saccharomyces cerevisiae EBY100에 형질전환시켜 형질전환체 EBY100/pCTXYN를 얻었다. 형질전환체들을 xylan이 포함된 YPDG 배지에서 배양 후 활성염색을 통하여 고찰성의 형질전환체를 최종 선별하였다. 갈락토스 배지에서 자란 효모 형질전환체로부터 xynB는 성공적으로 표면발현되었고, xylan으로 부터 xylooligosaccharides를 효율적으로 생성함도 화인하였다. Endoxylanase 활성은 세포분획에서만 검출되었고 배양 48시간에 최종 1.9 unit/mL의 활성을 보였다. Xylooligosaccharides 생산을 위한 치적 반응 조건으로, 기질과 농도는 oat spelt xylan 6%, 효모 생촉매 농도는 5 unit/mL, 반응온도는 $50^{\circ}C$, 반응시간은 $2{\sim}4$시간이었다 효모 생촉매를 oat spelt xylan과 corncob xylan에 처리한 결과, xylotriose가 주성분이었다.

• Journal of Microbiology and Biotechnology
• /
• 제24권3호
• /
• pp.408-420
• /
• 2014

Yeast surface-displayed antibody libraries provide an efficient and quantitative screening resource for given antigens, but suffer from typically modest library sizes owing to low yeast transformation efficiency. Yeast mating is an attractive method for overcoming the limit of yeast transformation to construct a large, combinatorial antibody library, but the optimal conditions have not been reported. Here, we report a large synthetic human Fab (antigen binding fragment) yeast surface-displayed library generated by stepwise optimization of yeast mating conditions. We first constructed HC (heavy chain) and LC (light chain) libraries, where all of the six CDRs (complementarity-determining regions) of the variable domains were diversified mimicking the human germline antibody repertoires by degenerate codons, onto single frameworks of VH3-23 and $V{\kappa}1$-16 germline sequences, in two haploid cells of opposite mating types. Yeast mating conditions were optimized in the order of cell density, media pH, and cell growth phase, yielding a mating efficiency of ~58% between the two haploid cells carrying HC and LC libraries. We constructed two combinatorial Fab libraries with CDR-H3 of 9 or 11 residues in length with colony diversities of more than $10^9$ by one round of yeast mating between the two haploid HC and LC libraries, with modest diversity sizes of ${\sim}10^7$. The synthetic human Fab yeast-displayed libraries exhibited relative amino acid compositions in each position of the six CDRs that were very similar to those of the designed repertoires, suggesting that they are a promising source for human Fab antibody screening.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2003년도 생물공학의 동향(XIII)
• /
• pp.468-472
• /
• 2003

Recently, genetic engineering techniques have been used to display various heterologous peptides and proteins (enzyme, antibody, antigen, receptor and fluorescence protein, etc.) on the yeast cell surface. Living cells displaying various enzymes on their surface could be used repeatedly as 'whole cell biocatalysts' like immobilized enzymes. We constructed a yeast based whole cell biocatalyst displaying T. reesei cellobiohydrolase I (CBH I ) on the cell surface and endowed the yeast-cells with the ability to degrade cellulose. By using a cell surface engineering system based on ${\alpha}-agglutinin,$ CBH I was displayed on the cell surface as a fusion protein containing the N-terminal leader peptide encoding a Gly-Ser linker and the $Xpress^{TM}$ epitope. Localization of the fusion protein on the cell surface was confirmed by confocal microscopy. In this study, we report on the genetic immobilization of T. reesei CBH I on the S. cerevisiae and hydrolytic activity of cell surface displayed CBH I.

• Journal of Microbiology and Biotechnology
• /
• 제24권5호
• /
• pp.661-666
• /
• 2014

Both lactic acid productivity and cell growth were linearly correlated with yeast extract supplementation in batch fermentation. During conventional continuous operation, although fresh feed was introduced into the bioreactor with a significantly low dilution rate (0.04 $h^{-1}$), the amount of yeast extract employed was not enough to maintain the growth of microorganism. However, when the fresh feed contained 100 g/l glucose and 2 g/l yeast extract during cell-recycle continuous operation at a dilution rate of 0.04 $h^{-1}$, more than 90 g/l lactic acid was continuously produced, with the average productivity of 3.72 $g/l{\cdot}h$. In this experiment, 82 g of yeast extract (77% of reduction yield) could be reduced for the production of 1 kg of lactic acid compared with batch fermentation of a similar volumetric productivity.

• 환경생물
• /
• 제20권1호
• /
• pp.35-39
• /
• 2002

The significance of cell ploidy and repair ability for the radioprotective efficiency of cysteamine was studied in DNA repair - proficient and repair - deficient yeast cells irradiated $^{60}C0\;\gamma-rays.$ Results have been obtained for the cell survival of two groups of yeasts-diplont and haplont cells, both in haploid and diploid states. For diploid Saccharomyces cerevisiae yeast cells, the correlation between the radio-protective action of cysteamine and the cell repair capacity was demonstrated. Such a correlation was not clearly expressed for haploid yeast cells. In addition, evidence was obtained indicating that the degree of the radioprotective action was independent of the number of chromosome sets in haplont yeast Pichia guilliermondii cells and in some radiosensitive mutants defective in the diploid-specific recovery. It is concluded on this basis that the radioprotective action may involve the cellular recovery process, which may be mediated by a recombination-like mechanism, for which the diploid state is required. The results obtained clearly show that the radioprotective effect was dependent on DNA repair status and indicate that the mechanism of the radioprotective action may be realized on the level of primary radiation damage production as well as on the level of postradiation recovery from potentially lethal radiation damage.