• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.104.2-104.2
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• 2010

농산 부산물인 볏짚을 이용하여 수송연료인 휘발유를 대체할 수 있는 바이오에탄올을 생산하기 위한 전단계인 전처리와 당화에 대한 연구를 수행하였다. 볏짚은 농산 부산물 중에서 비교적 발생량이 많으며, 목질계 바이오매스에 비해 소프트하기 때문에 전처리가 용이하다는 장점이 있다. 전처리 방법으로는 여러 가지가 있으나, 본 연구에서는 증기폭쇄에 의한 전처리 방법을 채택하였다. 당화실험은 생물학적 방법인 효소당화를 하였다. 전처리 실험결과 온도가 낮고 처리 시간이 짧을수록 고형물 및 삼성분에 대한 수율이 높은 것으로 나타났다. 삼성분 중의 Glucan 수율은 $180^{\circ}C$ 실험에서 68-71%를 보였으며, $200^{\circ}C$ 실험에서는 59-64%를 보였다. Xylan은 거의 대부분이 소실되어 Xylan을 회수하는 전처리로써는 적합하지 않은 방법으로 나타났다. 반면 Lignin은 거의 제거가 되지 않았다. 당화 실험결과 $180^{\circ}C$에서 전처리한 폭쇄재는 당화 수율이 50%에도 미치지 못하였으나, $200^{\circ}C$에서 전처리한 폭쇄재는 70% 내외를 보여 주었다. 특히 분쇄 세척 멸균한 효소당화 수율은 90%가 넘는 높은 수율을 보였다. 전처리 수율과 당화수율을 종합하여 수율을 분석한 결과 $200^{\circ}C$ 전처리 실험조건에서 효소당화시 미처리 시료와 분쇄 세척 시료보다 멸균까지 실시한 조건에서 Glucan의 종합수율이 55% 내외로 월등히 높은 것으로 나타났다. 증기폭쇄에 의한 볏짚의 전처리는 Glucan의 수율이 낮아 손실이 많은 것으로 나타났으며, 이를 보완할 수 있는 전처리 조건 혹은 다른 전처리 방안이 요구된다.

• Journal of the Korean Wood Science and Technology
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• v.40 no.3
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• pp.147-155
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• 2012

Switchgrass was selected as a promising biomass resource for bioethanol production through popping pretreatment, enzymatic saccharification and fermentation using commercial cellulase and xylanase, and fermenting yeast. The reducing sugar yields of popping pretreated switchgrass after enzymatic saccharification were above 95% and the glucose in thesaccharificaiton solution to ethanol conversion rate after fermentation with $Saccharomyces$ $cerevisiae$ was reached to 89.6%. Chemical compositions after popping pretreatment developed in our laboratory were 40.8% glucose and 20.3% xylose, with much of glucose remaining and only xylose decreased to 4.75%. This means that the hemicelluloses area broke off during popping pretreatment. FE-SEMexamination of substrate particles after popping pretreatment was showed fiber separation, and tearing and presence of numerous micro pores. These changes help explain, enhanced enzymatic penetration resulting in improved hydrolysis of switchgrass particles after popping pretreatment.

• Korean Journal of Agricultural Science
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• v.43 no.4
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• pp.641-649
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• 2016

This study was conducted to evaluate the yield of bio-ethanol produced by separate hydrolysis and fermentation (SHF) with the pretreated rapeseed straw (RS) using crude enzyme of Cellulomonas flavigena and Saccharomyces cereviase. Crude enzyme of C. flavigena showed enzymatic activity of 14.02 U/mL for CMC 133.40 U/mL, for xylan 15.21 U/mL, for locust gum and 15.73 U/mL for rapeseed straw at pH 5.0 and $40^{\circ}C$, respectively. The hemicellulose contents of RS was estimated to compromise 36.62% of glucan, 43.20% of XMG (xylan + mannan + galactan), and 2.73% of arabinan by HPLC analysis. The recovering ratio of rapeseed straw were investigated to remain only glucan 75.2% after 1% $H_2SO_4$ pretreatment, glucan 45.44% and XMG 32.13% after NaOH, glucan 44.75% and XMG 5.47% after $NH_4OH$, and glucan 41.29% and XMG 41.04% after hot water. Glucan in the pretreatments of RS was saccharified to glucose of 45.42 - 64.81% by crude enzyme of C. flavigena while XMG was made into to xylose + mannose + galactose of 58.46 - 78.59%. Moreover, about 52.88 - 58.06 % of bio-ethanol were obtained from four kinds of saccharified solutions by SHF using S. cerevisiae. Furthermore, NaOH pretreatment was determined to show the highest mass balance, in which 21.22 g of bio-ethanol was produced from 100 g of RS. Conclusively, the utilization of NaOH pretreatment and crude enzyme of Cellulomonas flavigena was estimated to be the best efficient saccharification process for the production of bio-ethanol with rapeseed straw by SHF.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.241-246
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• 2014

This study is to compare characteristics of saccharification reactions applying to enzymatic hydrolysis of pretreated fallen leaves for bio-ethanol production. It experimented pretreatment of acid, alkaline in the chemical. This experiment includes preteatment of acid and alkaline in chemical, soaking, shaking and autoclaving method, which were applied to biomass. In result, the glucose production from alkaline-NaOH method was 263 mg glucose/ g biomass comparing with them of acid-HCl method. Thus, alkaline-NaOH method is superior than the acid-HCl method for chemical preteatment of fallen leaves. Also, when various chemical treatments were compared, they were all. Based on the results of this study, we found that leaves, one of biomass, are possible in pretreatment and enzymatic hydrolysis process, and they are likely to affect bio-ethanol production in the future.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.828-834
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• 2010

An ethanol-producing yeast strain, CHFY0201, was isolated from soil in South Korea using an enrichment technique in a yeast peptone dextrose medium supplemented with 5% (w/v) ethanol at $30^{\circ}C$. The phenotypic and physiological characteristics, as well as molecular phylogenetic analysis based on the D1/D2 domains of the large subunit (26S) rDNA gene and the internally transcribed spacer (ITS) 1+2 regions, suggested that the CHFY0201 was a novel strain of Schizosaccharomyces pombe. During shaking flask cultivation, the highest ethanol productivity and theoretical yield of S. pombe CHFY0201 in YPD media containing 9.5% total sugars were $0.59{\pm}0.01$ g/l/h and $88.4{\pm}0.91%$, respectively. Simultaneous saccharification and fermentation for ethanol production was carried out using liquefied cassava (Manihot esculenta) powder in a 5-l lab-scale jar fermenter at $32^{\circ}C$ for 66 h with an agitation speed of 120 rpm. Under these conditions, S. pombe CHFY0201 yielded a final ethanol concentration of $72.1{\pm}0.27$ g/l and a theoretical yield of $82.7{\pm}1.52%$ at a maximum ethanol productivity of $1.16{\pm}0.07$ g/l/h. These results suggest that S. pombe CHFY0201 is a potential producer for industrial bioethanol production.

• New & Renewable Energy
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• v.3 no.1 s.9
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• pp.38-45
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• 2007

To characterize thermo-chemical feature of sugar conversion of woody biomass, poplar wood ($Populus\;alba{\times}glandulosa$) powder was treated with supercritical water system. Supercritical water treatment (SCWT) was performed for 60 seconds at different temperatures (subcritical zone 350; supercritical zone $300,\;400,\;425^{\circ}C$) under two pressures $230{\pm}10atm$ as well as $330{\pm}10atm$, respectively, using flow type system. After separation of solid residues from SCWT products, the monomeric sugars in aqueous part converted from poplar wood powder were quantitatively determined by high performance anionic exchange chromatography [HPAEC] equipped with PAD detector and Carbo Pac PA10 column. As the temperature treated increased, the degradation of poplar wood powder was enhanced and ca 83% of woody biomass was dissolved into the water at $425^{\circ}C$. However, the pressure didn't help the degradation of biomass components. At subcritical temperature range, xylose was first formed by degradation of xylan, which is main hemicellulose component in hardwood species, while cellulose degradation started at the transition zone between sub and supercritical conditions and was remarkably accelerated at the supercritical temperature. In the supercritical water system the maximum yield of monomeric sugars amounts to ca. 7.3% based on oven dried wood weight at $425^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.13 no.1
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• pp.59-64
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• 1985

In order to utilize Citrus peel as fermentative substrate of microorganisms, enzymatic saccharification of Citrus peel by the crude enzyme of Aspergillus sp. GF 015 isolated and identified from nature was investigated. When the fungus was cultured at $27^{\circ}C$ for 3 days in wheat bran medium containing 0.6% $NH_4NO_3$ and 0.05% $KH_2PO_4$, the maximal production of the enzyme was observed. Optimal conditions for enzymatic reaction of crude enzyme were 15ml(97.5 unit)/g of enzyme solution to Citrus peel powder ratio, pH4.0, $45^{\circ}C$ of temperature and 12 hours of reaction time. As the result of saccharifying Citrus peel under optimum conditions, reducing sugar on the weight of dry matter was formed 60.2% and saccharifying rate was 76.3%. The sugar solution obtained were mainly composed of glucose, xylose and galacturonic acid. Hydrolyzing enzymes produced by Aspergillus sp. GF 015 were pectinase, cellulase and xylanase.

• Advances in environmental research
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• v.9 no.1
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• pp.55-64
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• 2020

The problems with unsorted municipal waste are always associated with disposal issues as it requires a large area for landfilling or high energy used for incineration. In recent years, an autoclaving technique has been considered a promising approach which could minimize the volume of organic waste from being directly disposed or incinerated. In this work, an attempt was done to study the saccharification potential of organic residues under elevated temperature Thermal treatment involving hot water bath was applied to treat the organic residue ranging from 60℃ to 100℃ for 30 and 60 minutes. The result obtained showed an increasing trend for the concentration of glucose and carbohydrate. However, the result for lignocellulose content which contains various component includes extractive, holocellulose, hemicellulose, cellulose and lignin show variation. Based on the thermal treatment carried out, the result indicated that the trend of glucose and carbohydrate content. The highest percentage of glucose that can be obtained 978.602 ㎍/ml which could be obtained at 90℃ at 60 minutes. The carbohydrate also shows an increasing trend with 0.234 mg/ml as the highest peak achieved at 80℃ for 30 minutes treatment. However, it was found that the lignocellulose content varies with temperature and time. The statistical analysis was carried out using two-ways ANOVA shows an interaction effect between the independent variables (temperature and contact time) and the saccharification effects on the food wastes. The result shows a variation in the significant effect of independent variables on the changes in the composition of food waste.

• Microbiology and Biotechnology Letters
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• v.14 no.5
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• pp.415-420
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• 1986

Alcohol fermentation of uncooked naked barley was carried out by the combined action of the maceration enzyme from black Aspergillus niger and the glucoamylase from Rhizopus sp. The combined enzyme preparation was found to be effective in maceration and saccharification of the raw naked barley starch. The Hydrolysis rate measured by the amount of glucose liberated reached more than 70% at pH 4.5 and 3$0^{\circ}C$ after 76 hrs. For alcohol fermentation without cooking, the naked barley mash of 18% initial total sugar was pretreated with concentrated sulfuric acid (0.15 weight % of the mash volume) at 55$^{\circ}C$ for 2hr, and used for alcohol fermentation. A simultaneous saccharification and fermentation was carried out at pH 4.8 and 3$0^{\circ}C$ for 96 hrs. Under this fermentation condition, 3.5% increase in alcohol yield together with 2.0% increase in alcohol concentration were obtained when compared with the conventional cooking fermentation.

• Mycobiology
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• v.44 no.3
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• pp.155-161
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• 2016

The most economically important species used in a wide range of fermentation industries throughout Asia belong to Aspergillus section Flavi, which are morphologically and phylogenetically indistinguishable, with a few being toxigenic and therefore a major concern. They are frequently isolated from Korean fermentation starters, such as nuruk and meju. The growing popularity of traditional Korean alcoholic beverages has led to a demand for their quality enhancement, therefore requiring selection of efficient non-toxigenic strains to assist effective fermentation. This study was performed to classify the most efficient strains of Aspergillus section Flavi isolated from various types of traditional wheat nuruk, based on a polyphasic approach involving molecular and biochemical evaluation. A total of 69 strains were isolated based on colony morphology and identified as Aspergillus oryzae/flavus based on internal transcribed spacer and calmodulin gene sequencing. Interestingly, none were toxigenic based on PCR amplification of intergenic regions of the aflatoxin cluster genes norB-cypA and the absence of aflatoxin in the culture supernatants by thin-layer chromatography analysis. Saccharification capability of the isolates, assessed through ${\alpha}-amylase$ and glucoamylase activities, revealed that two isolates, TNA24 and TNA15, showed the highest levels of activity. Although the degrees of variation in ${\alpha}-amylase$ and glucoamylase activities among the isolates were higher, there were only slight differences in acid protease activity among the isolates with two, TNA28 and TNA36, showing the highest activities. Furthermore, statistical analyses showed that ${\alpha}-amylase$ activity was positively correlated with glucoamylase activity (p < 0.001), and therefore screening for either was sufficient to predict the saccharifying capacity of the Aspergillus strain.