• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.297-302
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• 1999

Simultaneous saccharification and fermentation (SSF) experiments were carried out with a lignocellulosic biomass. The effects of temperature on enzymatic saccharification and the ethanol fermentation were also investigated. The batch SSF process gave a final ethanol concentration of 10.44 g/l and equivalent glucose yield of 0.55 g/g, which was increased by 67％ or higher over the saccharification at 42℃. The optimal operating condition was found to vary in several parameters, such as the transmembrane pressure, permeation rate, and separation coefficient, related to the SSF combined with membrane system (semi-batch system). When the fermentation was operated in a semi-batch mode, the efficiency of the enzymes and yeast lasted three times longer than in a batch mode.

• Journal of Microbiology and Biotechnology
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• 제16권9호
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• pp.1355-1361
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• 2006

The simultaneous saccharification and fermentation (SSF) process consists of concurrent enzymatic saccharification and fermentation. In the present cybernetic model, the saccharification process, which is based on the modified Michaelis-Menten kinetics and enzyme inhibition kinetics, was combined with the fermentation process, which is based on the Monod equation. The cybernetic modeling approach postulates that cells adapt to utilize the limited resources available to them in an optimal way. The cybernetic modeling was suitable for describing sequential growth on multiple substrates by Brettanomyces custersii, which is a glucose- and cellobiose-fermenting yeast. The proposed model was able to elucidate the SSF process in a systematic manner, and the performance was verified by previously published data.

• KSBB Journal
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• 제25권6호
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• pp.565-571
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• 2010

To develop thermostable ethanol fermentative yeast strain for lignocellulosic simultaneous saccharification and fermentation, high ethanol producing yeast, Saccharomyces cerevisiae CHY1012 and thermostable yeast, Kluyveromyces marxianus CHY1703 were fused by protoplast fusion. The thermostable fusant, CHY1612 was identified as a Kluyveromyces marxianus by phenotypic and physiological characteristics, as well as molecular analysis based on the D1/D2 domains of the large subunit (26S) rDNA gene and the internally transcribed spacer (ITS) 1 + 2 regions. For lignocellulosic ethanol production, AFEX pretreated barley straw at $150^{\circ}C$ for 90 min was used in a simultaneous saccharification and fermentation (SSF) process using thermotolerant CHY1612. The SSF from 16% pretreated barley straw at $43^{\circ}C$ gave a saccharification ratio of 90.5%, a final ethanol concentration of 38.5 g/L, and a theoretical yield of 91.2%. These results show that K. marxianus CHY1612 has potential for lignocellulosic ethanol production through simultaneous saccharification and fermentation with further development of process.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권3호
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• pp.205-209
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• 2003

Solubilization of domestic household waste through Steam explosion with Subsequent ethanol production by the microbial saccharifitation and fermentation of the exploded product was studied. The effects of steam explosion on the changes of the density, viscosity, pH, and amounts of extractive components in artificial household waste were determined. The composition of artificial waste used was similar to leftover waste discharged from a typical home in Japan. Consecutive microbial saccharification and fermentation, and simultaneous microbial saccharification and fermentation of the Steam-exploded product were attempted using Aspergillus awamori, Trichoderma viride, and Saccharomyces cerevisiae; the ethanol yields of each process were compared. The highest ethanol yield was obtained with simultaneous microbial saccharification and fermentation of exploded product at a steam pressure of 2 MPa and a steaming time of 3 min.

• 한국미생물·생명공학회지
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• 제11권3호
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• pp.181-185
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• 1983

증자하지 않은 Cassava의 생전분의 ethanol 발효생산을 위하여 Aspergilius shirousami 가생산하는 당화효소를 이용하여 단순당화 및 동시당화 발효를 하였다. Cassava 생전분의 당화률은 증자한 것에 비해 30% 정도였으며 10배의 효소를 가하여도 60%밖에 안되었으나. 동시당화-발효에서는 당화율이 크게 증가하여 ethanol 생성량이 증자한 전분에 비해 90% 이상이 되었다.

• Journal of Microbiology and Biotechnology
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• 제21권7호
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• pp.703-710
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• 2011

Enzymatic saccharification of corn stover using Phanerochaete chrysosporium and Gloeophyllum trabeum and subsequent fermentation of the saccharification products to ethanol by Saccharomyces cerevisiae and Escherichia coli K011 were achieved. Prior to simultaneous saccharification and fermentation (SSF) for ethanol production, solid-state fermentation was performed for four days on ground corn stover using either P. chrysosporium or G. trabeum to induce in situ cellulase production. During SSF with S. cerevisiae or E. coli, ethanol production was the highest on day 4 for all samples. For corn stover treated with P. chrysosporium, the conversion to ethanol was 2.29 g/100 g corn stover with S. cerevisiae as the fermenting organism, whereas for the sample inoculated with E. coli K011, the ethanol production was 4.14 g/100 g corn stover. Corn stover treated with G. trabeum showed a conversion 1.90 and 4.79 g/100 g corn stover with S. cerevisiae and E. coli K011 as the fermenting organisms, respectively. Other fermentation co-products, such as acetic acid and lactic acid, were also monitored. Acetic acid production ranged between 0.45 and 0.78 g/100 g corn stover, while no lactic acid production was detected throughout the 5 days of SSF. The results of our experiment suggest that it is possible to perform SSF of corn stover using P. chrysosporium, G. trabeum, S. cerevisiae and E. coli K011 for the production of fuel ethanol.

• 한국미생물·생명공학회지
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• 제16권3호
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• pp.213-218
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• 1988

섬유소 폐기물인 볏짚으로부터 butanol를 생산하기 위하여 Clostridium acetobutylicum KCTC1037 와 cellulase(from Trichoderma viride)을 발효액에 동시에 첨가하여 발효시키는 동시당화 발효법(Simultaneous saccharification and fermentation, SSF)을 수행하였다. Alkali 처리한 볏짚을 발효기질로 사용한 결과 그 농도를 25%로 사용하였을 때 최고 150mM의 butanol이 생산되었고, 15% 볏짚을 사용하였을 때는 97mM의 butanol이 생산되었다. 그러나 ball milled 볏짚의 경우 발효산물 중 대부분이 acetate와 butyrate로 주로 산이 생산되었으며 따라서 solventogenesis는 거의 일어나지 않았다. 또한 그 농도별 실험에서 보면 8%의 ball milled 볏짚 사용시 66mM의 butanol이 생산된 반면 그 이상의 농도에서는 butanol 생산량이 점차 감소하는 추세를 보였으며 acetate, butyrate 같은 산은 계속 증가 추세를 보였다. 이것으로 보아 ball milled 볏짚에는 butanol 발효 과정 중 acidogenesis에 서 solventogenesis로의 전이 (shift)를 방해하는 어떤 인자가 있으리라고 추측되었으며 alkali 처리방법에 의해서 이 방해자는 제거될 수 있는 것으로 관찰되었다.

• 대한환경공학회지
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• 제32권6호
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• pp.609-614
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• 2010

유기성 폐기물인 음식물쓰레기를 이용하여 유용한 에너지원인 바이오에탄올을 생산하고자 하였으며, 에탄올 생산 균주는 Saccharomyces cerevisiae를 이용하였다. 음식물쓰레기의 당화를 위하여 carbohydrase와 glucoamylase 효소를 이용한 결과 carbohydrase가 glucoamylase보다 당화효율이 우수하였으며, carbohydrase 이용시 건조 음식물쓰레기 기준 glucose 생산량 0.63 g/g-TS을 얻을 수 있었다. 에탄올 생산은 동시당화발효에서 0.44 g/$L{\cdot}hr$, 분리당화발효가 0.27 g/$L{\cdot}hr$이었다.

• KSBB Journal
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• 제30권3호
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• pp.125-131
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• 2015

Kluyveromyces marxianus is a well-known thermotolerant yeast. Although Saccharomyces cerevisiae is the most commonly used yeast species for ethanol production, the thermotolerant K. marxianus is more suitable for simultaneous saccharification and fermentation (SSF) processes. This is because enzymatic saccharification usually requires a higher temperature than that needed for the optimum growth of S. cerevisiae. In this study, we compared the fermentation patterns of S. cerevisiae and K. marxianus under various temperatures of fermentation. The results show that at a fermentation temperature of $45^{\circ}C$, K. marxianus exhibited more than two fold higher growth rate and ethanol production rate in comparison to S. cerevisiae. For SSF using starch or corn stover as the sole carbon source by K. marxianus, the high temperature ($45^{\circ}C$) fermentations showed higher enzymatic activities and ethanol production compared to SSF at $30^{\circ}C$. These results demonstrate the potential of the thermotolerant yeast K. marxianus for SSF in the industrial production of biofuels.

• KSBB Journal
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• 제28권6호
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• pp.366-371
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• 2013

Ethanol productions were performed by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes using seaweed, Enteromorpha intestinalis (sea lettuce). Pretreatment conditions were optimized by the performing thermal acid hydrolysis and enzymatic hydrolysis for the increase of ethanol yield. The pretreatment by thermal acid hydrolysis was carried out with different sulfuric acid concentrations in the range of 25 mM to 75 mM $H_2SO_4$, pretreatment time from 30 to 90 minutes and solid contents of seaweed powder in the range of 10~16% (w/v). Optimal pretreatment conditions were determined as 75 mM $H_2SO_4$ and 13% (w/v) slurry at $121^{\circ}C$ for 60 min. For the further saccharification, enzymatic hydrolysis was performed by the addition of commercial enzymes, Celluclast 1.5 L and Viscozyme L, after the neutralization. A maximum reducing sugar concentration of 40.4 g/L was obtained with 73% of theoretical yield from total carbohydrate. The ethanol concentration of 8.6 g/L of SHF process and 7.6 g/L of SSF process were obtained by the yeast, Saccharomyces cerevisiae KCTC 1126, with the inoculation cell density of 0.2 g dcw/L.