• KSBB Journal
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• 제14권5호
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• pp.561-565
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• 1999

Optimum conditions for vacuum-drying ad cultivation of yeast cells for the production of active dry yeast were examined. At lower temperature, more drying time was required to dry the yeast pellet to reach the desirable water content(8%). Optimum temperature of vaccum oven and time for drying was 63$^{\circ}C$ and 90 min, respectively. Optimum medium composition for flask culture using cane molasses as the substrate were 0.25% sugar, 0.013% $K_2$HPO$_4$, 0.1% $K_2$HPO$_4$. and 0.125% (NH$_4$)$_2$SO$_4$. Culture temperature $25^{\circ}C$ gave the highest survival rate of dired yeast. After finishing fed-batch culture and the culture was left in the fermentor without adding any sugar or nutrient, survival of the dried yeast harvested from the fermentor increased to 86.0% after 36 hr. It was also observed that the yeast cells with higher budding rates showed lower survival rate.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권4호
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• pp.288-305
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• 2000

A review on the main aspects associated with yeast flocculation and its application in biotechnological processes is presented. This subject is addressed following three main aspects-the basics of yeast flocculation, the development of "new" flocculating yeast strains and bioreactor development. In what concerns the basics of yeast flocculation, the state of the art on the most relevant aspects of mechanism, physiology and genetics of yeast flocculation is reported. The construction of flocculating yeast strains includes not only the recombinant constitutive flocculent brewer's yeast, but also recombinant flocculent yeast for lactose metabolisation and ethanol production. Furthermore, recent work on the heterologous $\beta$-galactosidase production using a recombinant flocculent Saccharomyces cerevisiae is considered. As bioreactors using flocculating yeast cells have particular properties, mainly associated with a high solid phase hold-up, a section dedicated to its operation is presented. Aspects such as bioreactor productivity and culture stability as well as bioreactor hydrodynamics and mass transfer properties of flocculating cell cultures are considered. Finally, the paper concludes describing some of the applications of high cell density flocculating bioreactors and discussing potential new uses of these systems.e systems.

• 한국식생활문화학회지
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• 제34권2호
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• pp.201-207
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• 2019

This review summarizes the studies on a wide variety of yeast found in kimchi and the effects of yeast on kimchi fermentation, and discusses the direction for further research. Yeast belongs to the genera Trichosporon, Saccharomyces, Sporisorium, Pichia, Lodderomyces, Kluyveromyces, Candida, Debaryomyces, Geotrichum, Kazachstania, Brassica, Yarrowia, Hanseniaspora, Brettanomyces, Citeromyces, Rhodotorula, and Torulopsis have been identified using culture-dependent methods and metagenomics analysis. The application of yeast as a starter into kimchi has resulted in an extension of shelf life and improvement of sensory characteristics due to a decrease in the amount of lactic acid. On the other hand, some yeast cause kimchi spoilage, which typically appears as an off-odor, texture-softening, and white-colony or white-film formation on the surface of kimchi. In contrast to lactic acid bacteria, there are limited reports on yeast isolated from kimchi. In addition, it is unclear how yeast affects the fermentation of kimchi and the mechanism by which white colony forming yeast predominate in the later stage of kimchi fermentation. Therefore, more research will be needed to solve these issues.

• Animal Bioscience
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• 제35권9호
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• pp.1400-1407
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• 2022

Objective: This research determined the chemical composition and the apparent and standardized ileal digestibility (AID and SID) of crude protein (CP) and amino acids (AA) in whole yeast and autolyzed yeast derived from sugarcane ethanol production fed to growing pigs. Methods: Six growing pigs were randomly allocated in a replicated 3×3 Latin square design with 3 diets and 3 periods of 7 days each, resulting in a total of 6 experimental replications. Three assay diets were formulated using whole yeast, autolyzed yeast, or soybean meal as the sole sources of dietary CP and AA. Pigs were allowed to adapt to the assay diets for 5 days. Thereafter, ileal digesta samples were collected continuously for 8 hours on days 6 and 7. Results: There was no difference in the chemical composition between whole yeast and autolyzed yeast, but whole yeast had low digestibility of CP and AA due to the presence of a rigid cell wall. As conducting autolysis can induce cell wall damage, the AID and SID of CP and AA were greater in autolyzed yeast than in whole yeast. Conclusion: The information obtained on the SID of CP and AA in both yeast products can be used for the accurate estimation of the bioavailability of CP and AA in feed formulations. The yeast products derived from sugarcane ethanol production are an alternative protein source in pig diets.

• 한국식품영양과학회지
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• 제21권5호
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• pp.534-538
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• 1992

시판 9개 회사의 요구르트를 $25^{\circ}C$에 보관하면서 yeast 오염에 의한 팽창 현상이 관찰되는 시료에서 10균주의 yeast와 starter를 분리하여 potassium sorbate농도에 따른 생육 특성을 조사한 결과 start로 사용되고 있는 유산균중 potassium sorbate에 대해 영향을 받지 않는 균주가 있는 반면 다소간의 생육 억제 현상을 보이는 균주를 관찰할 수 있었다. 분리 yeast는 모두 성장이 억제되었으며 potassium sorbate 농도가 증가함에 따라 억제 현상은 더욱 뚜렷하였다. 선발된 유산균과 yeast를 skim milk에 혼합 배양한 결과 유산균은 potassium sorbate 0.3% 첨가에 의해 영향을 받지 않았으며, yeast의 경우 성장 현상은 관찰되지 않았으나 potassium sorbate 첨가구는 배양 18시간 이후 생균수가 감소하는 경향을 나타내었다. 선발된 유산균으로 yogurt를 제조한 후 선발 yeast를 오염시켜 $4{\pm}1{\circ}C$와 $25{\pm}1{\circ}C$에서 7일간 저장하면서 생균수의 변화를 조사한 결과 전 저장 기간중 유산균의 변화는 관찰할 수 없었으며 $10^9/ml$을 유지하였다. 오염 yeast는 $4{\pm}1{\circ}C$의 경우 대조구에서는 성장을 관찰할 수 없었으며, potassium sorbate 첨가구의 경우 저장이 계속됨에 따라 완만하게 감소하였고, $25{\pm}1{\circ}C$의 경우에서도 0.3% 첨가구의 경우 차츰 감소하는 경향을 나타내었다.

• 한국가금학회지
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• 제22권2호
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• pp.77-84
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• 1995

In order to investigate the effect of feeding live yeast culture on the performance of laying hens, a feeding trial was conducted with 96 20-wk-old Hy4ine brown layers during their laying period of 60 wk. The live yeast culture used was a product from Saccharomyces cerevisiae that was cultured on the corn-based substrate followed by careful drying of whole material not to lose the viability of yeast. Three levels of yeast culture as 0.5, 1.0, and 2.0% for three treatments and 0% for the control were included in the experimental diets. The feeding trial was carried out for 60 wk from August 26, 1992 to October 26, 1993. To evaluate the performance of layers during cold or hot periods as affected by the yeast culture feeding, data from the 12-wk winter period and 12-wk summer period were separated and analyzed accordingly. During 60 wk of laying period hen-day egg production was slightly but significantly(P<.05) improved by feeding the yeast culture. The average egg weight and daily egg weight(g /day) were also increased by the yeast culture. Feeding the yeast culture did not increase feed intake but feed efficiency was improved significantly (P<.05). No significant difference was detected in egg or eggshell qualities between control and yeast culture-treated groups. Feed intake and egg weight were not affected by the yeast culture feeding under both cold and hot period, but egg production and feed efficiency during hot summer improved significantly by its feeding. This result indicates that the effectiveness of the yeast culture feeding is greater during summer than winter for laying hens.

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

• 대한화학회지
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• 제39권10호
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• pp.812-817
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• 1995

방향족 니트로 화합물을 선택적으로 환원시켜 치환체가 있는 아닐린을 생성하는 것은 산업적 측면에서 볼때 의미있는 반응이다. 본 연구에서는 Bakers' Yeast-NaOH의 환원작용에 의하여 m-Bromonitrobenzene 의 니트로기가 선택적으로 빠르게 환원되어 치환체가 있는 아닐린 화합물이 형성됨을 확인하였고 특히 Nitrosobenzene이 수산화 나트륨이 없는 조건에서 Bakers' Yeast만의 작용에 의해 환원되어 아닐린을 생성함을 확인하였다. 또한 Nitrosobenzene의 Bakers' Yeast 환원에 미치는 저해제들의 효과 및 온도, pH의 영향 등을 조사하였다.

• 농업과학연구
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• 제47권3호
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• pp.395-402
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• 2020

A total of 60 growing pigs (25.50 ± 1.63 kg) were used in a 6-week trial to investigate the effects of diet supplementation with brewer's yeast (Saccharmyces cerevisiae) on growth performance, nutrient digestibility, and fecal score of growing pigs. Pigs were randomly allocated to one of two dietary treatments [six replications (five pigs·pen^-1)] according to initial body weight. The dietary treatments included: 1) control, basal diet (CON); 2) basal diet supplemented with 1% brewer's yeast. Dietary supplementation with brewer's yeast showed significant improvement in body weight (BW) at weeks 4 and 6; the average daily gain (ADG) and gain : feed ratio (G/F) was higher during week 4 and overall compared with CON (p < 0.05). Brewer's yeast supplementation in the diet had no significant on the nutrient digestibility. There was no significant difference in the fecal score of CON and brewer's yeast supplementation in the diet. In conclusion, the results indicate that dietary supplementation with brewer's yeast can improve growth performance in growing pigs. The results showed that supplementation of brewer's yeast in the diet of growing pigs had a positive effect on the ADG in growing pigs, but no significant effect on nutrient digestibility and fecal score when supplemented with brewer's yeast in the diet of growing pigs.

• 한국식품영양학회지
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• 제8권4호
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• pp.280-288
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• 1995

Because yeast is rich in vitamins, nucleotides and essential amino acids, it has been used as a nutrient and dietary supplements. Particularly yeast extract functions as a seasoning, flavor enhancer in meats. In this study, naturally occurring insoluble components during yeast extract process by autolysis were microanalyses by using SEM, XRD, HPLC, GC, FT-lR and DSC. On the basis of useful datas, authors have characterized the analytical points for the purpose of improving products in the preparation of yeast extract.