• Journal of Microbiology and Biotechnology
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• 제25권6호
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• pp.837-844
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• 2015

Carob waste is a useful raw material for the second-generation ethanol because 50% of its dry weight is sucrose, glucose, and fructose. To optimize the process, we have studied the influence of the initial concentration of sugars on the fermentation performance of Saccharomyces cerevisiae. With initial sugar concentrations (S₀ ) of 20 g/l, the yeasts were derepressed and the ethanol produced during the exponential phase was consumed in a diauxic phase. The rate of ethanol consumption decreased with increasing S₀ and disappeared at 250 g/l when the Crabtree effect was complete and almost all the sugar consumed was transformed into ethanol with a yield factor of 0.42 g/g. Sucrose hydrolysis was delayed at high S₀ because of glucose repression of invertase synthesis, which was triggered at concentrations above 40 g/l. At S₀ higher than 250 g/l, even when glucose had been exhausted, sucrose was hydrolyzed very slowly, probably due to an inhibition at this low water activity. Although with lower metabolic rates and longer times of fermentation, 250 g/l is considered the optimal initial concentration because it avoids the diauxic consumption of ethanol and maintains enough invertase activity to consume all the sucrose, and also avoids the inhibitions due to lower water activities at higher S₀ .

• Journal of Forest and Environmental Science
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• 제26권2호
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• pp.137-148
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• 2010

The high costs for ethanol production with lignocellulosic biomass as a second generation energy materials currently deter commercialization of lignocellulosic biomass, especially wood biomass which is considered as the most recalcitrant material for enzymatic hydrolysis mainly due to the high lignified structure and the nature of the lignin component. Therefore, overcoming recalcitrance of lignocellulosic biomass for converting carbohydrates into sugar that can subsequently be converted into biobased fuels and biobased products is the primary technical and economic challenge for bioconversion process. This study was mainly reviewed on the research trend of the enhancement of enzymatic hydrolysis for lignocellulosic biomass after pretreatment in bioethanol production process.

• Macromolecular Research
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• 제12권6호
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• pp.581-585
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• 2004

A copolymer P[OSA-MI] was synthesized by copolymerization of its corresponding monomers, N-phenyl maleimide (MI) and 2-octen-l-ylsuccinic anhydride (OSA). The polymer (poly[2-[1-(2,5-dioxo-l-phenylpyrroli­din-3-ylmethyl)heptyl]-succinic acid 4-(2-$\{$ethyl-[4-(4-nitrophen-ylazo)phenyl]amino$\}$ethyl)ester]) P[DR1MA-MI] was obtained from the reaction of P[OSA-MI] with 2-[4-(4-nitrophenylazo)-N-ethylphenylamino] ethanol (DR1). A stable monolayer of P[DRIMA-MI] was formed by spreading the solution of the polymer in chloroform. In Y-type Langmuir-Blodgett (LB) films prepared using this Langmuir-Blodgett method, the second harmonic waves generated from adjacent mono layers canceled each other out. In X-and Z-type LB films, the second harmonic intensity increased upon increasing the number of monolayers, but this increase was somewhat smaller than predicted by the square law. This phenomenon is due to defects or imperfect alignment of the dipoles in the LB film. The generation of second harmonic waves from Y-type LB films having an even number of mono layers supports this argument. The degree of imperfection seemed to increase as the number of layers increased. The second-order nonlinear optical properties of spin-cast films of these polymers were also measured. The largest second harmonic coefficient of the poled P[DRIMA-MI] film coated on a glass plate was 19 pm/V.

• Journal of Microbiology and Biotechnology
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• 제23권10호
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• pp.1403-1412
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• 2013

Ethanol fuel production from lignocellulosic biomass is emerging as one of the most important technologies for sustainable development. To use this biomass, it is necessary to circumvent the physical and chemical barriers presented by the cohesive combination of the main biomass components, which hinders the hydrolysis of cellulose and hemicellulose into fermentable sugars. This study evaluated the hydrolytic capacity of enzymes produced by yeasts, isolated from the soils of the Brazilian Cerrado biome (savannah) and the Amazon region, on sugarcane bagasse pre-treated with $H_2SO_4$. Among the 103 and 214 yeast isolates from the Minas Gerais Cerrado and the Amazon regions, 18 (17.47%) and 11 (5.14%) isolates, respectively, were cellulase-producing. Cryptococcus laurentii was prevalent and produced significant ${\beta}$-glucosidase levels, which were higher than the endo- and exoglucanase activities. In natura sugarcane bagasse was pre-treated with 2% $H_2SO_4$ for 30 min at $150^{\circ}C$. Subsequently, the obtained fibrous residue was subjected to hydrolysis using the Cryptococcus laurentii yeast enzyme extract for 72 h. This enzyme extract promoted the conversion of approximately 32% of the cellulose, of which 2.4% was glucose, after the enzymatic hydrolysis reaction, suggesting that C. laurentii is a good ${\beta}$-glucosidase producer. The results presented in this study highlight the importance of isolating microbial strains that produce enzymes of biotechnological interest, given their extensive application in biofuel production.

• 한국식품영양과학회지
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• 제34권8호
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• pp.1143-1150
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• 2005

한국에서 널리 식용으로 이용되고 있는 미역, 다시마, 톳(갈조류), 파래(녹조류), 김(홍조류)의 항산화효과와 총 플라보노이드와 폴리페놀 함량과의 관련성을 알아보고자 건조 상태의 시판 해조류로부터 에탄올 추출시료를 얻은 후 $Fe^{2+}$로 유도된 지질과산화 억제율, DPPH 라디칼 소거율 및 MDA-BSA 결합 저해율을 측정하는 3가지 방법으로 항산화효과를 검정 하였고, 총 플라보노이드와 폴리페놀 함량을 측정하였다. 그 결과, 녹조류인 파래의 항산화효과가 가장 우수하였는데, 특히 지질과산화물이 단백질과 결합하는 반응을 매우 효과적으로 저해하였다. 그 다음 김과 다시마의 항산화효과가 우수하였으며, 미 역과 톳은 항산화효과가 거의 없었다. 총 플라보노이드 함량은 미역이 11.63 mg/g 건조무게로 가장 높았고, 총 폴리페놀 함량은 파래가 8.97 mg/g 건조무게로 가장 높았다. 한편, 3가지 방법에 의해 측정된 해조류의 항산화효과 모두가 총 폴리페놀 함량과 유의한 양의 상관관계를 보였으며, 특히 지질과산화억제율과 매우 높은 상관관계를 나타내어(r=0.9351, p<0.0001), 해조류에서의 항산화효과에 폴리페놀 성분이 크게 기여할 가능성을 보였다.

• Elastomers and Composites
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• 제56권3호
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• pp.136-151
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• 2021

Biomass lignin, a waste produced during the paper and bio-ethanol production process, is a cheap material that is available in large quantities. Thus, the interest in the valorization of biomass lignin has been increasing in industrial and academic areas. Over the years, lignin has been predominantly burnt as fuel to run pulping plants. However, less than 2% of the available lignin has been utilized for producing specialty chemicals, such as dispersants, adhesives, surfactants, and other value-added products. The development of value-added lignin-derived co-products should help make second generation biorefineries and the paper industry more profitable by valorizing lignin. Another possible approach towards value-added applications is using lignin as a component in plastics. However, blending lignin with polymers is not simple because the polarity of lignin molecules results in strong self-interactions. Therefore, achieving in-depth insights on lignin characteristics and structure will help in accelerating the development of lignin-based products. Considering the multipurpose characteristics of lignin for producing value-added products, this review will shed light on the potential applications of lignin and lignin-based derivatives on polymeric composite production. Moreover, the challenges in lignin valorization will be addressed.

• Korean Chemical Engineering Research
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• 제61권3호
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• pp.412-418
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• 2023

The surge in the oil prices, increasing global population, climate change, and waste management problems are the major issues which have led to the development of biofuels from lignocellulosic wastes. Cellulosic or second generation (2G) bioethanol is produced from lignocellulosic biomass via pretreatment, hydrolysis, and fermentation. Pretreatment of lignocellulose is of considerable interest due to its influence on the technical, economic and environmental sustainability of cellulosic ethanol production. In this study, furniture waste sawdust was subjected to alkaline peroxide (H₂O₂) for the production of reducing sugars. Sawdust was pretreated at different concentrations from 1-3% H₂O₂ (v/v) loadings at a pH of 11.5 for a residence time of 15-240 min at 50, 75 and 90 ℃. Optimum pretreatment conditions, such as time of reaction, operating temperature, and concentration of H₂O₂, were varied and evaluated on the basis of the amount of total reducing sugars produced. It was found that the changes in the amount of lignin directly affected the yield of reducing sugars. A maximum of 50% reduction in the lignin composition was obtained, which yielded a maximum of 75.3% total reducing sugars yield and 3.76 g/L of glucose. At optimum pretreatment conditions of 2% H₂O₂ loading at 75 ℃ for 150 min, 3.46 g/L glucose concentration with a 69.26% total reducing sugars yield was obtained after 48 hr. of the hydrolysis process. Pretreatment resulted in lowering of crystallinity and distortion of the sawdust after the pretreatment, which was further confirmed by XRD and SEM results.

• 한국식품영양과학회지
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• 제33권6호
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• pp.921-929
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• 2004

한국산 메밀, 수수, 기장, 율무의 돌연변이억제효과와 항산화효과 및 총 flavonoid와 polyphenol 함량을 측정하였다. 이를 위하여 에탄을 추출시료를 얻은 후 Ames test 방법으로 돌연변이 억제효과를 검색하였고, Fe$^{2+}$로 유도된 지질과산화 억제율, DPPH 라디 칼 소거율 및 MDA-BSA 결합억제율을 측정하는 3가지 방법으로 항산화효과를 검정하고, 총 flavonoid와 polyphenol 함량을 측정한 결과를 요약하면 다음과 같다. 에탄올 추출시료의 $IC_{50}$/에 의한 지질과산화 억제효과를 비교한 결과 메밀(0.174 mg/ assay), 수수(0.241 mg/assay), 율무(1.891 mg/assay), 기장(2.873 mg/assay) 순이었으며 에탄을 추출시료의 $IC_{50}$/을 계산하여 DPPH 라디칼 제거능을 비교한 결과 메밀(0.264 mg/assay), 수수(2.135 mg/assay), 기장(2.902 mg/assay), 율무(4.667 mg/assay) 순이었다. 지질과산화물-단백질 결합 억제효과는 에탄을 추출시료의 $IC_{50}$/을 기준으로 비교한 결과 메밀(3.73 mg/assay), 율무(51.82 mg/assay), 기장(120.59 mg/assay), 수수(449.43mg/assay)의 순이었다. S. Typhimurium TA98에서 에탄올 추출물 4.5 mg/assay농도에서 2-Nitrofluorene에 의 한 직접돌연변이를 저해하는 비율은 수수(50.2%), 기장(20.3%), 메밀(18.5%), 율무(17.5%)의 순이었으며, S. Typhimurium TA100에서 sodium azide에 의한 직접돌연변이를 저해하는 비율은 기장(100%), 율무(78.6%), 수수(23.7%), 메밀(10.1%)의 순이었다. S. Typhimurium TA98 또는 TA100에서 에탄올 추출물이 2-Anthramine에 의한 간접돌연변이 억제효과는 기장, 수수, 율무, 메밀 모두 우수하였으며, 특히 기장과 수수의 효과가 매우 좋았다. 총 flavonoid 함량은 메밀(1.41mg/g), 수수(1.17 mg/g), 기장(0.96 mg/g), 율무(0.66 mg/g)순이었고, 총 polyphenol 함량은 메밀(3.71 mg/g), 수수(1.76 mg/g), 율무(1.7 mg/g), 기장(1.09 mg/g) 순으로 각각 DPPH 라디칼제거효과 및 지질과산화억제효과의 순과 일치하였다. 총 flavonoid 함량은 DPPH 라디칼 제거효과에 대한 $IC_{50}$/ 값과 높은 상관관계(r=-0.9924, p<0.01)를 나타내었다.