• Journal of Microbiology and Biotechnology
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• 제23권10호
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• pp.1460-1471
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• 2013

Microalgal biofuel production from wastewater has economic and environmental advantages. This article investigates the lipid production from high chemical oxygen demand (COD) bioethanol wastewater without dilution or additional nutrients, using a newly isolated heterotrophic microalga, Chlorella vulgaris LAM-Q. To enhance lipid accumulation, the combined effects of important operational parameters were studied via response surface methodology. The optimal conditions were found to be temperature of $22.8^{\circ}C$, initial pH of 6.7, and inoculum density of $1.2{\times}10^8cells/ml$. Under these conditions, the lipid productivity reached 195.96 mg/l/d, which was markedly higher than previously reported values in similar systems. According to the fatty acid composition, the obtained lipids were suitable feedstock for biodiesel production. Meanwhile, 61.40% of COD, 51.24% of total nitrogen, and 58.76% of total phosphorus were removed from the bioethanol wastewater during microalgal growth. In addition, 19.17% of the energy contained in the wastewater was transferred to the microalgal biomass in the fermentation process. These findings suggest that C. vulgaris LAM-Q can efficiently produce lipids from high-concentration bioethanol wastewater, and simultaneously performs wastewater treatment.

• International Journal of Industrial Entomology and Biomaterials
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• 제33권1호
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• pp.24-30
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• 2016

1-Deoxynojirimycin (DNJ) have been extensively investigated for their α-glucosidase inhibitor on postprandial hyperglycemia, and applied in nutraceuticals and medicine for preventing or delaying progression of type 2 diabetes. However, the amount of DNJ in mulberry leaves is low (about 0.1%), therefore, more effective extraction method is needed. This study was performed to develop microbial DNJ for biological methods of DNJ as an alternative to the chemical methods. In this study, we obtained evidence for Bacillus subtilis that produce DNJ in large quantities by high performance liquid chromatography. Inhibition of α-glucosidase activity was determined to DNJ production or non-production. Investigation of the effect of mulberry leaves powder concentration (1~5%), using the DNJ high-production bacteria, provided evidence for microbial mass production of DNJ. When the 4% mulberry leaf powder for 9 days was used, the α-glucosidase inhibitory activity was over the 85%. Also, the results presented in this study confirm DNJ yield's increasement in microbes using the various of nutrients and provide insight of ways to improve DNJ yields in microorganisms.

• Asian-Australasian Journal of Animal Sciences
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• 제17권5호
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• pp.705-711
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• 2004

Growth promoters were added to skim milk to retain the viability of Lactobacillus acidophilus and Bifidobacterium longum to help the product meet the "therapeutic minimum" at the time of consumption. The experiments were divided into two parts. The first part of the study used chicory inulin, isomalto-oligosaccharides and sucrose to investigate the effects of sugars on the activity of L. acidophilus and B. longum. The results indicated that the addition of isomalto-oligosaccharides stimulated growth of L. acidophilus and B. longum, resulting in a higher level of the probiotics after one month storage and yielded better $\beta$-galactosidase activity during fermentation. The second part studied the effects of three growth promoters on the viability of the probiotic cultures and the response surface method was employed to find the optimal ratio for addition of the growth promoters. The optimal ratio for added calcium gluconate, sodium gluconate and N-acetylglucosamine in fermented milk drinks were established. The response surface method proved to be a very effective way of optimizing the activity of probiotic cultures when developing a new fermented milk drink.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권3호
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• pp.167-172
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• 2001

Staphylokinase (SAK) was produced in B. subtilis using two different promoter systems, i.e. the P43 and sacB promoters. To maximize SAK expression in B. subtilis, fermentation control strategies for each promoter were examined. SAK, under P43, a vegetative promoter transcribed mainly by $\sigma$(sup)B containing RNA polymerase, was overexpressed at low dissolved oxygen (D.O.) levels, suggesting that the sigB operon is somewhat affected by the energy charge of the cells. The expression of SAK at the 10% D.O. level was three times higher than that at the 50% D.O. level. In the case of sacB, a sucrose-inducible promoter, sucrose feeding was used to control the induction period and induction strength. Since sucrose is hydrolyzed by two sucrose hydrolyzing enzymes in the cell and culture broth, the control strategy was based on replenishing the loss of sucrose in the culture. With continuous feeding of sucrose, WB700 (pSAKBQ), which contains the SAK gene under sacB promoter, yielded ca. 35% more SAK than the batch culture. These results present efficient promoter-dependent control strategies in B. subtilis host system for foreign protein expression.

• KSBB Journal
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• 제18권6호
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• pp.473-478
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• 2003

본 연구의 목적은 메탄을 최대로 발생시킬 수 있는 최적조건을 탐색하는데 있다. 탐색한 최적조건 인자로는 온도, pH, 탄소원, 그리고 질소원이며, 메탄 발생에 영향을 주는 저해제에 대해서도 조사하였다. 결과적으로, 온도는 3$0^{\circ}C$, pH는 중성영역, 탄소원은 methanol, 질소원은 NH$_4$Cl에서 최대의 메탄을 얻을 수 있었으며, 메탄 생성에 대한 저해재의 영향을 조사한 결과 10 mM 미만의 극소량이라도 2-bromoethanesulfonic acid가 존재할 경우 메탄 발생량이 감소하는 결과를 보였다. 메탄 발생에 대한 pH 변화를 조사해 본 결과, pH가 7.5에서 6.5로 내려가는 동안에는 메탄 발생량이 증가하였으나, 6.5에서 6.0으로 변화되면서는 메탄 발생량이 감소하였다. 따라서 pH 변화를 실시간으로 측정하여 상분리 발효를 적용하면 최적 메탄 생성 조건을 유지할 수 있을 것으로 사료된다. 또한 메탄 발생 시 배지 내에 생성되는 유기산을 측정해 본 결과 생성된 유기산 중 formic acid가 0.1M로 최대량을 보였다.

• 유기물자원화
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• 제11권1호
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• pp.101-101
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• 2003

본 연구는 남은 음식물을 유산균을 이용하여 발효 사료화 하기 위해 실시하였다. 발효를 촉진시키기 위한 균주로는 Lactobacillus acidophilus를 사용하였고 최적의 발효조건을 갖는 공기 주입량을 알아보기 위해 시료의 발효 조건을 각각 달리 하였다. 시료는 교반하지 않고 공기주입 또한 없는 혐기적 조건의 것과 50rpm의 속도로 교반하면서 0.25v.v.m의 공기를 주입한군, 70rpm의 속도로 교반하면서 0.5v.v.m의 공기를 주입한 군으로 나누었다. 시료는 모두 $37^{\circ}C$로 유지하면서 48시간 발효 시키며 12시간 단위로 시료를 채취하였다. p.H와 유기산함량, 환원당함량과 유산균수를 측정하여 남은 음식물을 발효시키기 위한 최적의 공기 주입량을 알아보았다. 실험결과 50rpm 0.25v.v.m에서 가장 낮은 p.H를 보여주었고 유기산 함량과 환원당 함량은 70rpm 0.5v.v.m에서 가장 높은 함량을 보였다. 유산균은 50rpm 0.25v.v.m에서 가장 많은 증식되었음을 보여주어 적절한 공기의 주입이 남은 음식물의 발효를 촉진하는 것으로 보여진다.

• 한국수소및신에너지학회논문집
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• 제26권5호
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• pp.409-415
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• 2015

This study was performed to optimize the integrated anaerobic digestion (AD) and microbial electrolysis cells (MECs) for the enhanced hydrogen production. The optimum operational conditions of integrated AD and MECs were obtained using response surface methodology. The optimum substrate concentration and operational pH were 10 g/L and 6.8, respectively. In the confirm test, 1.43 mol $H_2/mol$ hexose was achieved, which was 2.5 times higher than only AD. After 40 to 60 hour at seeding, the volatile fatty acids (VFAs) in reactor of AD were not changed. However the VFAs of reactor of AD-MECs were reduced by 61.3% (acetate: 76.4%, butyrate: 50.0%, lactate: 55.0%).

• 한국수소및신에너지학회논문집
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• 제21권2호
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• pp.136-142
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• 2010

Photobiological $H_2$ production was compared using purple non-sulfur bacteria Rhodobacter sphaeroides KD131 in the medium containing various organic acids as the carbon source and electron doner under illumination of $110\;W/m^2$ using halogen lamp at $30^{\circ}C$. The organic acids used were 0~120 mM acetate, butyrate, lactate and malate. Initial pH 7.0 and cell concentration 1.0 at 660nm were increased to pH 8 and 4.4~5.1, respectively during 24hrs of photo-fermentation when lactate and malate were used. However, acetate and butyrate increased pH to 9 and cell concentration to 3.2~3.9 of malate at the same experimental conditions. Optimum ranges of organic acids concentration and carbon/nitrogen ratio were 30~60 mM and 10~20, respectively. When malate was used as the substrate, maximum $H_2$ production 1.1 ml $H_2$/ml broth, which is equivalent to 1.97 mol $H_2$/mol malate was observed.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.111-122
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• 2013

The steam explosion-chemical pretreatment is a more effective wood pretreatment technique than the conventional physical pretreatment by accelerating reactions during the pretreatment process. In this paper, two-stage pretreatment processes of hardwood were investigated for its enzymatic hydrolysis and the succinic acid yield from the pretreated solid. The first stage pretreatment was performed under conditions of low severity to optimize the amount of solid recovery. In the second stage pretreatment washed solid material from the first stage pretreatment step was impregnated again with chemical (alkaline or chlorine-based chemicals) to remove a portion of the lignin, and to make the cellulose more accessible to enzymatic attack. The effects of pretreatment were assessed by enzymatic hydrolysis and fermentation, after the two stage pretreatments. Maximum succinic acid yield (16.1 g $L^{-1}$ and 77.5%) was obtained when the two stage pretreatments were performed at steam explosion -3% KOH.

• 한국미생물·생명공학회지
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• 제51권1호
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• pp.18-25
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• 2023

After random mutagenesis, the mutant Lactobacillus plantarum GNS300 showed improved exopolysaccharide production as determined by the quantification of total sugar. The mutant L. plantarum GNS300 produced 2.82 g/l of exopolysaccharide which showed 79.62% improved exopolysaccharide production compared with the parental strain. When exopolysaccharide of L. plantarum GNS300 was analyzed, the exopolysaccharide is composed of galactose (93.35%) and glucose (6.65%). Through the optimization of fermentation conditions using a bioreactor, 2.93 g/l of exopolysaccharide was produced from 20 g/l of glucose at 35℃, 500 rpm, and 0.1 vvm for 12 h. The mutant L. plantarum GNS300 exhibited 69.18% higher antioxidant activity than that from the parental strain, which might be caused by higher exopolysaccharide production. The concentrated supernatant of the mutant L. plantarum GNS300 inhibited the growth of gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) and gram-negative bacteria (Escherichia coli, Vibrio parahaemolyticus, and Salmonella typhimurium).