Performance evaluations of yeast based microbial fuel cells improved by the optimization of dead zone inside carbon felt electrode

현규환,김성준,권용재 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.11

The performance of yeast-based microbial fuel cells (MFCs) and the growth pattern of yeast were evaluated with the optimization of dead zone within carbon felt (CF) electrode. Yeast cells were grown onto the different CFs that have 1 to 4mm thicknesses, while optical and electrochemical evaluations were implemented to determine the optimal growth pattern of yeast and to elucidate a relationship between the growth pattern of yeast and the performance of MFC. According to the evaluations, biofilm consisting of high-density yeast cells is formed in the upper 1mm height of CF electrode. As the height goes down, density of yeast cells is reduced to less than half of the upper biofilm, and by calculating the growth rate of yeast cells per CF volume, it is recognized that the coverage of biocatalyst including yeast cell increases from 0.191 to 0.406 mol/cm3 with decreasing CF thickness. Then, the performance of MFCs using biocatalysts including yeast cells grown on different thick CFs is measured to investigate how the growth pattern of yeast cells affects the performance of MFCs. Results show their maximum power density (MPD) increases linearly as the area that yeast cells are filled increases, and when CF thickness is 1mm, MPD reaches 417.13 W/m3.

Construction of a Large Synthetic Human Fab Antibody Library on Yeast Cell Surface by Optimized Yeast Mating

( Du San Baek ),( Yong Sung Kim ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.3

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 Vκ1-16 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 109 by one round of yeast mating between the two haploid HC and LC libraries, with modest diversity sizes of ~107. 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.

Manipulation of Rumen Fermentation by Yeast: The Effects of Dried Beer Yeast on the In vitro Degradability of Forages and Methane Production

Ando, S.,Khan, R.I.,Takahasi, J.,Gamo, Y.,Morikawa, R.,Nishiguchi, Y.,Hayasaka, K. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.1

The effects of the addition of yeast on in vitro roughage degradability and methane production were investigated in order to clarify the effects of yeast on the rumen microbes and to establish methods of rumen manipulation. Three roughages (whole crop corn, rice straw and Italian ryegrass) were incubated for 3, 6, 12 and 24 h with or without dried beer yeast following the method described by Tilley and Terry. Using the same method, these roughages were incubated with or without yeast extract, albumin or purified DNA. In vitro methane production was measured with or without dried beer yeast at 12 and 24 h. The degradability of yeast was found to be 57 and 80% at 12 and 24 h, respectively. The rate of degradation of fraction b was 6.16%/h. There was a significant increase in roughage degradability at 6 h (p<0.05), 12 h (p<0.05) and 24 h (p<0.01) by dried yeast addition. The degradability of all three roughages was higher in the samples treated with yeast extract than in the no addition samples except in the case of rice straw incubated for 12 h. Nevertheless, the magnitude of increment was smaller with the addition of yeast extract than without the addition of yeast. With the addition of purified DNA, there were significant increases in roughage degradability at 6 h (p<0.01), 12 h (p<0.01) and 24 h (p<0.05); however, higher degradability values were detected in the samples to which albumin was added, particularly at 6 h. If the degradability values of the no addition samples with those of samples containing yeast, yeast extract, DNA and albumin were compared, the largest difference was found in the samples to which yeast was added, although it is worth noting that higher values were observed in the yeast extract samples than in the DNA or albumin samples, with the exception of the case of rice straw incubated for 24 h. Methane production was significantly increased at both 12 and 24 h incubation. The increment of roughage degradation and methane production brought about by the addition of dried beer yeast to the samples was thought to be due to the activation of rumen microbes. Water soluble fraction of yeast also seemed to play a role in ruminal microbe activation. The increment of degradability is thought to be partially due to the addition of crude protein or nucleic acid but it is expected that other factors play a greater role. And those factors may responsible for the different effects of individual yeast on ruminal microbes.

Effects of Strains of Saccharomyces cerevisiae and Incubation Conditions on the In vitro Degradability of Yeast and Roughage

Ando, S.,Nishiguchi, Y.,Hayasaka, K.,Yoshihara, Y.,Takahashi, J.,Iefuji, H. Asian Australasian Association of Animal Productio 2005 Animal Bioscience Vol.18 No.3

The in vitro degradability of yeast and the effect of yeast on the in vitro degradability of forage may differ in terms of the specific yeast strains or their incubation conditions. Thus in experiment 1, two strains of sake yeast (strainK7 and strainK9) and one strain of bakers' yeast (KY5649) were incubated in an aerobic condition. In experiment 2, aerobically or anaero bically incubated K7 was used for investigating the in vitro degradability of yeast, the effect of yeast on the in vitro degradability of forage, and the degradability of yeast by pepsin and pronase treatment. The in vitrodegradability of bakers' yeast was significantly (p<0.05) higher than those of sake yeasts. The in vitro degradability of anaerobically incubated yeast was significantly (p<0.01) higher than that of aerobically incubated yeast. The degradability of bakers' yeast by pepsin treatment was significantly (p<0.01) higher than that of the sake yeasts. The degradability of bakers' yeast by pronase treatment was slightly higher than that of the two sake yeasts, while the degradability of anaerobically incubated yeast by both enzymes, respectively, was significantly (p<0.01) higher than that of aerobically incubated yeast. The degradability of forages was increased significantly (p<0.05) by the addition of yeasts. The degradability of roughage by sake yeast tended to be higher than that by the bakers' yeast. The degradability of roughage was significantly (p<0.05) higher by anaerobically incubated yeast than by aerobically incubated yeast. Given the above results, it seems that in vitro degradability of yeast and the magnitude of the increment of roughage degradation differ among the yeast strains and their incubation conditions.

알로에 베라(A. vera)와 알로에 사포나리아(A. saponaria)로 부터 효모의 분리 및 계통분석

최성창 ( Sung Chang Choi ),김명욱 ( Myung Uk Kim ),김종식 ( Jong Shik Kim ) 한국환경농학회 2013 한국환경농학회지 Vol.32 No.3

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. BACKGROUND: Several yeast species have potential applications in biotechnology and the identification of such yeast species is of great interest. The first step in the identification of yeasts is the establishment of an effective isolation method. Thus, we compared the efficacy of different yeast media in the isolation of yeast associated with Aloe vera and Aloe saponaria. METHODS AND RESULTS: In this study, we spread homogenized A. vera and A. saponaria leaves onto 4 different yeast selective media containing chloramphenicol, streptomycin, Triton X-100 and L-sorbose. We observed high selectivity for yeast and many colonies on media. We isolated 67 yeast strains from A. vera and 42 yeast strains from A. saponaria. We used phylogenetic analysis to identify the yeast isolates based on ITS region sequencing and performed sequence analysis on representative isolates from each agar plate. Further, we compared the sequences obtained with reference sequences. The yeast species isolated from A. vera were as follows: 56 isolates of Meyerozyma, 9 isolates of Cryptococcus, and 1 isolate each of Rhodotorula and Sporobolomyces. Those isolated from A. saponaria were as follows: 41 isolates of Rhodosporidium and 1 isolate of Sporobolomyces. CONCLUSION(S): All the isolates obtained using large agar plate containing chloramphenicol, streptomycin, Triton X-100 and L-sorbose were identified as yeast. Therefore, we concluded that this method is useful for selective screening of yeast species.

Chemical composition and standardized ileal digestibility of crude protein and amino acid in whole yeast and autolyzed yeast derived from sugarcane ethanol production fed to growing pigs

Kaewtapee Chanwit,Jantra Nontawut,Petchpoung Krittaya,Rakangthong Choawit,Bunchasak Chaiyapoom 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.9

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. 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.

맥주박을 이용한 알코올 발효사료의 최적 발효조건 규명

김창혁,박병기,오상집,성경일,김현숙,홍병주,신종서,Kim, C.H.,Park, B.K.,Ohh, S.J.,Sung, K.I.,Kim, H.S.,Hong, B.J.,Shin, J.S. 한국축산학회 2005 한국축산학회지 Vol.47 No.4

본 시험은 맥주박의 알코올 발효가 발효특성 및 사료의 영양적 가치에 미치는 영향을 검토하기 위하여 실시하였다. 본 시험에 이용한 시험사료는 맥주박과 파쇄 옥수수를 50:50(풍건상태)의 비율로 혼합하여 혐기 발효에 의하여 발효사료를 제조하였다. 발효 조건은 당밀 첨가 수준(0, 2 및 5%), yeast 첨가 수준(0, 0.1, 0.5, 1.0 및 2.0%) 및 발효 온도(4, 10, 30, 40 및 50$^{\circ}C$)에 따른 변화를 검토하였으며, 각 조건에 의한 알코올 함량, live yeast cell number (LYCN) 및 pH 변화를 조사하였다. 당밀 첨가에 따른 알코올 함량은 첨가수준이 증가할수록 높게 생성되었다. 발효 24시간 동안에 yeast 0.1, 0.5, 1.0 및 2.0% 첨가에 따른 알코올 함량은 각각 1.9, 2.4, 3.1 및 3.1%로 나타나, yeast 첨가수준 1% 까지는 yeast의 첨가수준이 증가할수록 시험사료중의 알코올 생성량도 비례적으로 증가하였으나(P<0.05), yeast 첨가수준 1.0 이상에서는 일정한 양의 알코올 이 생성되었다. 발효 초기의 LYCN은 yeast 첨가수준이 높을수록 높게 나타났으나(P<0.05), 발효 48시간 후의 LNCN은 0.1% 이하에서는 유의적으로 낮게 나타났다(P<0.05). 발효 온도에 따른 알코올 생성량은 발효 온도 30 및 40$^{\circ}C$에서 유의적으로 높은 결과를 보였으며(P<0.05), 30$^{\circ}C$와 40$^{\circ}C$ 간의 알코올 생성량은 30$^{\circ}C$에서 높은 경향이었다. 발효 온도에 따른 pH는 발효 온도가 낮을수록 발효 24시간까지 급격히 감소하는 것으로 나타났다(P<0.05). 이상의 결과로 미루어 맥주박의 사료적 가치를 높이기 위해 yeast의 첨가량, 당밀(발효기질), 발효온도 및 발효시간 등의 요인을 고려하였을 경우, 본 시험의 조건하에서 원활한 알코올 발효와 발효사료의 품질을 향상시키기 위한 적정 발효조건은 당밀 5%와 yeast 1%를 첨가하여 30$^{\circ}C$에서 24시간 동안 발효시키는 것이 가장 바람직한 것으로 나타났다. To determine the optimum fermentation condition, the 50:50 feed mixture of both crushed corn and wet brewer’s grain were anaerobically fermented at various conditions. Three supplementation levels(0, 2%, and 5%) of molasses, five supplementation levels(0, 0.1%, 0.5%, 1.0%, and 2.0%) of yeast and five different incubation temperatures(4$^{\circ}C$, 10$^{\circ}C$, 30$^{\circ}C$, 40$^{\circ}C$ and 50$^{\circ}C$) were tested to determine the optimum fermentation conditions. During fermentation, alcohol concentration, live yeast cell number (LYCN) and pH values of the mixture were analyzed. Alcohol concentrations of the fermented feed mixtures were proportionally increased with increasing level of molasses supplementation. After 24hr fermentation, alcohol concentrations at 0.1%, 0.5%, 1.0% and 2.0% of yeast supplementation was 1.9%, 2.4%, 3.1% and 3.1%, respectively. These results indicate a proportional increase of alcohol concentration with the increasing supplementation of yeast (P<0.05) up to 1%, thereafter showing plateau at 2% supplementation. LYCN was relatively high with more than 0.5% yeast supplementation, whereas the value was significantly low(P<0.05) at 0.1% yeast supplementation. Alcohol production was significantly higher at 30$^{\circ}C$ and 40$^{\circ}C$ than other incubation temperatures (P<0.05), with the highest concentration at 30$^{\circ}C$. pH was rapidly decreased until 24 hours of incubation with steeper decrease at lower temperatures(P<0.05). Based on there results, optimum fermentation conditions for the alcoholic-fermented feed production could be achieved with 5% supplementation of molasses, 1% supplementation of yeast, and 24hr long incubation at 30$^{\circ}C$.

건강 성인의 구강에서 분리되는 효모형 진균

김영아,이경원,정윤섭,조동희,권호근 대한임상병리학회 2000 대한임상병리학회지 Vol.20 No.1

시판 빵 효모의 발효 특성 및 제빵성에 관한 연구

김원주,한영숙 한국조리과학회 2004 한국식품조리과학회지 Vol.20 No.5

In this study, the author examined the fermentative abilities and baking properties of commercial baker's yeasts and suggested the fundamental data for the development of the yeast products industry. Carbon dioxide production, expansion abilities of doughs, and maltose fermentative abilities were measured with commercial yeasts. The fermentative abilities of various bread doughs were determined in comparison to a reference yeast and a selected yeast from commercial yeast. Various breads were prepared by these two yeasts and their sensory properties were evaluated. Y7, followed by Y5 and Y4, shooed higher ability than any other commercial yeasts in the gassing power of the dough, as measured by a Meissle fermenter. In the expansion abilities of the doughs made from various yeasts by M-Cylinder, Y7, followed by Y4 and Y5, showed the best expansion ability the results were similar to those for gassing power. Therefore, Y7 was selected. The maltose fermentative abilities of various yeasts in Atkin's liquid medium showed a higher value in Y5, Y7 and Y4. Selected yeast Y7 and the reference yeast K were used for determining the fermentative abilities of various bread doughs. For the various breads prepared by K and Y7, the qualities of the breads such as volume, weight and specific volume were measured. The volume by Y7 was higher in the straight dough bread, and that by K was higher in the sponge dough bread. In the sweet dough bread, both Y7 and K were excellent groups for it. Sensory properties of various breads made from K scored high on the items such as external properties and color in the straight dough bread. It also acquired a good score on the item of the crusts in the sweet dough bread. The overall acceptability of Y7 and K were similar.

누룩에서 분리한 양조용 효모를 이용한 쌀맥주의 품질특성 연구

이영복,고동준,정철 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.12

This study investigated the brewing properties of rice beer made with yeast isolated from traditional whole wheat nuruk. The experimental method was followed by alcohol fermentation and quality analysis for six months after separating the yeast from nuruk. The yeasts isolated from traditional nuruk showed normal fermentation characteristics, like those of commercial yeast, in terms of alcohol production capability, sugar content, and pH reducing power. Especially, the yeast (KCCM 301) isolated from whole wheat nuruk showed higher contents of glycogen and trehalose than that of commercial yeast, and so KCCM 301 yeast has excellent yeast vitality. Meanwhile, the yeast (KCCM 90301) isolated from traditional Nuruk produced significantly higher alcohol and ester contents than that of commercial yeast. This has a positive effect for supplementing the taste and aroma of rice beer. In conclusion, the yeasts isolated from whole wheat nuruk showed the general alcohol fermentation pattern and aroma content of rice beer. These yeasts seem to be effective in strengthening the flavor of rice beer. 본 연구는 전통 통밀누룩에서 분리된 효모의 쌀맥주 양조적성을 조사하는데 목적이 있다. 실험방법은 누룩에서 효모 분리 후 알코올 발효와 품질분석을 6개월간 진행하였다. 전통누룩에서 분리된 효모들은 알코올 생성능 및 당도, pH 감소력 등에서 상업용 효모와 같이 정상적인 발효특성을 보였다. 또한 연이은 2차, 3차 알코올 발효과정에서는 1차 알코올 발효보다 높은 발효력을 나타내어 발효기간이 1일가량 단축되는 결과를 보였다. 전통누룩에서 분리한 2종의 양조용 효모는 상업용효모 S. cereviaise(W107)와 발효특성을 비교했을 때 유사한 발효패턴을 보여 쌀맥주 양조적성에 적합한 것으로 나타났다. 특히 통밀 누룩에서 분리한 S. cereviaise(KCCM90301)효모의 글리코겐과 트레할로오스 함량이 상업용 효모에 비해 높아 효모활력이 우수한 것으로 나타났다. 또한 주요 아로마 성분인 고급알코올과 에스터 농도는 통밀누룩에서 분리한 효모가 상업용 효모에 비해 유의적으로 높은 농도를 나타냈다. 이는 쌀맥주의 맛과 향을 보완하는데 긍정적인 효과가 있는 것으로 판단된다. 결론적으로, 통밀 전통누룩에서 분리한 효모들은 일반적인 알코올 발효패턴과 맥주에서 나타나는 아로마 함량을 보였고, 상업용 효모에 비해서도 고급알코올과 에스터 성분이 유의적으로 높아 쌀맥주의 다소 밍밍한 맛을 보완하여 풍미를 강화는데 효과가 있는 것으로 판단된다.