• 한국해양바이오학회지
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• 제8권1호
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• pp.1-9
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• 2016

The hydrolysis of biomass to fermentable sugar (saccharification) and to oligosaccharide is an essential process in biotechnology including biorefinery and biofood. Various macroalgae are commercially cultivated in several Asian countries as a useful resource for food and agar production. Agar is a major component of the cell walls of red algae that can be hydrolyzed by agarase. Agarases are classified into ${\alpha}$-agarase (E.C. 3.2.1.158) and ${\beta}$-agarase (E.C. 3.2.1.81) according to the cleavage pattern and grouped in the glycoside hydrolase (GH) family (GH-16, GH-58, GH-86, GH-96, and GH-118) based on the amino acid sequences of the proteins. Agarases have been isolated from various bacteria found in seawater and marine sediments. To increase productivity of the enzyme, a research on recombinant enzymes has been done. The application of recombinant agarase can be possible in the various filed such as energy, food, cosmetics, medical and so on. This paper reviews the source, biochemical characteristics and production system of recombinant agarases for further study.

• 한국미생물·생명공학회지
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• 제13권1호
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• pp.59-64
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• 1985

감귤과피를 미생물의 발효기질로 이용하기 위하여 우선 미생물이 생산하는 효소로서 감귤과피의 최적 당화조건을 실험한 결과는 다음과 같다. 감귤과피를 용이하게 당화시키는 균주로서 Aspergillus sp. GF 015를 분리 동정하였으며, 그 균주(菌株)의 효소생산(酵素生産)은 밀기울 고체배지에 질소원($NH_4NO_3$)무기염($KH_2PO_4$)을 각각 0.6, 0.05%의 농도로 첨가하여 $27^{\circ}C$에서 3일간 배양하였을 때가 가장 좋았다. 한편 효소(酵素)의 최적반응조건(最的反應條件)은 기질과 조효소액의 비율 15ml (97.5 unit)/g peel, pH 4.0, 반응온도 $45^{\circ}C$, 반응 12시간이 적당하였다. 그 결과 원료감귤과피에 대해 60.2% 환원당을 생성하여 76.3%의 당화율을 나타내었으며 총당에 대한 환원당의 비율이 95%로 상당히 저분자화 되어 있다. 또한 최종당화액중의 주요성분은 glucose, xylose, galacturonic acid였으며, 감귤과피 분해에 관하여는 주효소는 cellulase, pectinase였는데 xylanase 도 약간 관여하였다.

• Journal of the Korean Wood Science and Technology
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• 제17권3호
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• pp.1-7
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• 1989

This study was performed to obtain the optimal condition that hydrolyzed exploded pine(Pinus densiflora), oak(Quercus serrata) and birch wood(Betula platyphylla var. japonica) by using sulfuric acid. The results obtained were summarized as follows: In hydrolysis of wood meal with sulfuric acid. maximum yield of sugar appeared that pine was 12 hours. oak and birch were 24 hours with 65% sulfuric acid. Futhermore, when wood meal and exploded woods were hydrolyzed with 65% sulfuric acid at $23^{\circ}C$ for 6 hours(primary hydrolysis), diluted to 3% and hydrolyzed again at $100^{\circ}C$ for 2 hours(secondary hydrolysis), the maximum sugar yield of wood meals were 6 hours. those of higher steam exploded pine wood was 3 hours. of lower steam exploded oak and birch woods were 6 hours. The sugar analyses of exploded wood showed that the amount of arabinose and xylose residue rapidly decreased. content of nemicelluose decreased with increase of steaming time and pressure.

• Journal of Microbiology and Biotechnology
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• 제28권4호
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• pp.588-596
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• 2018

An endo-${\beta}$-1,4-glucanase gene, cel9K, was cloned using the shot-gun method from Paenibacillus sp. X4, which was isolated from alpine soil. The gene was 2,994 bp in length, encoding a protein of 997 amino acid residues with a predicted signal peptide composed of 32 amino acid residues. Cel9K was a multimodular enzyme, and the molecular mass and theoretical pI of the mature Cel9K were 103.5 kDa and 4.81, respectively. Cel9K contains the GGxxDAGD, PHHR, GAxxGG, YxDDI, and EVxxDYN motifs found in most glycoside hydrolase family 9 (GH9) members. The protein sequence showed the highest similarity (88%) with the cellulase of Bacillus sp. BP23 in comparison with the enzymes with reported properties. The enzyme was purified by chromatography using HiTrap Q, CHT-II, and HiTrap Butyl HP. Using SDS-PAGE/activity staining, the molecular mass of Cel9K was estimated to be 93 kDa, which is a truncated form produced by the proteolytic cleavage of its C-terminus. Cel9K was optimally active at pH 5.5 and $50^{\circ}C$ and showed a half-life of 59.2 min at $50^{\circ}C$. The CMCase activity was increased to more than 150% in the presence of 2 mM $Na^+$, $K^+$, and $Ba^{2+}$, but decreased significantly to less than 50% by $Mn^{2+}$ and $Co^{2+}$. The addition of Cel9K to a commercial enzyme set (Celluclast 1.5L + Novozym 188) increased the saccharification of the pretreated reed and rice straw powders by 30.4% and 15.9%, respectively. The results suggest that Cel9K can be used to enhance the enzymatic conversion of lignocellulosic biomass to reducing sugars as an additive.

• 한국미생물·생명공학회지
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• 제49권1호
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• pp.88-94
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• 2021

해조류 중 홍조류인 꼬시래기(G. verrucosa)로부터 효모를 이용한 발효를 위해 열산가수분해, 효소당화 및 에탄올 발효수율 향상을 검토하고, 기존의 혼합당의 흡수효율을 높이기 위해 고농도 당 순치를 수행하였다. 열산가수분해는 200 mM 황산(H₂SO₄)을 이용하여 10% (w/v)의 꼬시래기(G. verrucosa)의 슬러리, 130℃의 온도에서 60분 동안 열산가수분해를 수행하였다. 또한 wild type 효모와 고농도 galactose에 순치(adaptive evolution)된 효모를 이용한 발효를 실시한 결과, wild type 효모의 경우 발효 144시간에 8.5 g/l 에탄올 발효로 에탄올수율계수 Y_EtOH = 0.19와 galactose에 순치된 효모의 경우 21.5 g/l 에탄올 발효로 에탄올수율계수 Y_EtOH = 0.50을 나타내었다. 이러한 연구결과는 해양 바이오매스인 해조류로부터 바이오 연료의 효율적인 생산방법을 제공할 수 있을 것으로 판단된다.

• 한국식품과학회지
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• 제30권4호
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• pp.728-732
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• 1998

시판되고 있는 가공식품 중 이취(異臭) 미역 및 이취(異臭) 쌀엿의 냄새성분을 규명하고, 이의 발생원인을 밝히고자 하였다. 이취 미역에서는 naphthalene,2-methylnaphthalene, 1-methylnaphthalene, 2,6-dimethylnaphthalene, 1,5-dimethylnaphthalene, 1,8-dimethylnaphthalene, 2,7-dimethylnaphthalene, 1,4,6-trimethylnaphthalene, 2,3,6-trimethylnaphthalene 등 나프탈렌계화합물들이 검출되었으며, 이취 쌀엿에서는 butanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid,tetradecanoic acid 등 유리지방산 및 2-furanmethanol, 2-furancarboxaldehyde 이 검출되었다. 미역의 이취 생성원인은 채취선박의 페인트 오염으로부터, 쌀엿은 변패된 쌀을 당화의 원료로 사용한데 기인한 것으로 본다.

• Journal of the Korean Wood Science and Technology
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• 제41권6호
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• pp.507-514
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• 2013

본 연구에서는 옥살산을 이용하여 팜 부산물 전처리를 수행하였으며 전처리에 사용된 산 촉매를 회수하였다. $150^{\circ}C$에서 전처리 후 액상가수분해산물에 포함된 발효가능한 당은 $20g/{\ell}$로 다른 조건에서 보다 높았으며 발효를 수행한 결과 72시간 후 $3.78g/{\ell}$의 에탄올을 생산하였다. 이것은 0.21 g/g의 에탄올 수율에 해당한다. $160^{\circ}C$ 이상의 전처리 조건에서 얻어진 액상가수분해산물의 발효는 이루어지지 않았다. 전기투석에 의해 액상가수분해산물에 포함된 옥살산은 대부분 회수되었으며 동시에 일부 발효저해물질도 제거되었다. 전기투석 후 액상가수분해산물을 이용한 에탄올 발효는 효율적으로 이루어졌으며 발효 24시간 후 $5.38g/{\ell}$의 에탄올을 생산하였다. 이것은 0.33 g/g의 에탄올 수율에 해당한다. 전처리 후 고형바이오매스를 이용하여 동시당화발효를 수행한 결과 모든 전처리 조건에서 96시간 후 $15g/{\ell}$ 이상의 에탄올을 생산하였으며, 특히 $170^{\circ}C$ 전처리 조건에서 $20.54g/{\ell}$의 높은 에탄올 생산을 나타냈다. 전기투석 후 액상가수분해산물을 이용하여 동시당화발효를 수행한 결과 에탄올 생산이 향상되었음을 확인할 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.206-209
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• 2008

The modified supercritical water treatment method is adopted for hydrolysis of wood powder, Populus alba$\times$glandulosa. This modified method is containing 0.05% HCl or $HNO_3$ as acid catalyst. The supercritical water treatment(SCW) was performed for 1 min. with $350^{\circ}C$, $380^{\circ}C$, $400^{\circ}C$ and $425^{\circ}C$, respectively, under 230 $\pm$ 10 atm using continuous flow system. When acid was added to powder prepared for SCW treatment, the yields of monomeric sugars were significantly increased. The lignin remained after supercritical treatment was applied to gel permeation chromatography(GPC) for molecular weight distribution analysis. Compared to the lignin produced from SCW treatment without acid catalyst, the average molecular weight of lignin compounds treated with acid was clearly decreased. Particularly, Mn/Mw ratio is decreased. This result shows supercritical water treatment of wood powder can change the molecular weight of lignin to small size. However, it is necessary to be further studied for exactly characterizing the lignin produced from supercritical water treatment.

• 한국식품영양학회지
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• 제29권5호
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• pp.698-705
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• 2016

천마의 불쾌취 개선을 위한 당화방법별 유산균 발효 결과는 3일 발효시 엿기름과 쌀누룩 이용 당화에서 총 산도가 각각 2.23, 2.33%이었으며, 생균수는 9.14 log cfu/mL와 9.27 log cfu/mL로 높았다. 발효기간이 길어짐에 따라 총 산도는 계속 높아져 3.35%까지 증가하였으나, 생균수는 3일 발효에서 가장 많았다. 아미노산 함량은 엿기름과 쌀누룩 이용 당화에서 높았고, 유리당 함량은 효소 이용 당화에서 높았으며, 그 중 glucose 함량이 가장 높았다. 천마 주성분인 gastrodin, p-HBA 등 주 성분 함량도 효소 이용 당화에서 가장 높았다. 이취성분인 p-cresol 함량이 엿기름 이용 당화에서 낮아 관능평가 결과에서도 엿기름을 이용하여 당화한 유산균 발효천마가 가장 좋은 기호도를 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.930-936
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• 2020

The red seaweed Gracilaria verrucosa has been used for the production of bioethanol. Pretreatment for monosaccharide production was carried out with 12% (w/v) G. verrucosa slurry and 500 mM HNO₃ at 121℃ for 90 min. Enzymatic hydrolysis was performed with a mixture of commercial enzymes (Cellic C-Tec 2 and Celluclast 1.5 L; 16 U/ml) at 50℃ and 150 rpm for 48 h. G. verrucosa was composed of 66.9% carbohydrates. In this study, 61.0 g/L monosaccharides were obtained from 120.0 g dw/l G. verrucosa. The fermentation inhibitors such as hydroxymethylfurfural (HMF), levulinic acid, and formic acid were produced during pretreatment. Activated carbon was used to remove HMF. Wild-type and adaptively evolved Saccharomyces cerevisiae, Candida lusitaniae, and Kluyveromyces marxianus were used for fermentation to evaluate ethanol production.