• Journal of Microbiology and Biotechnology
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• 제20권2호
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• pp.254-264
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• 2010

To obtain an efficient natural lignocellulolytic complex enzyme, we screened an efficient lignocellulose-degrading composite microbial system (XDC-2) from composted agricultural and animal wastes amended soil following a long-term directed acclimation. Not only could the XDC-2 degrade natural lignocelluloses, but it could also secrete extracellular xylanase efficiently in liquid culture under static conditions at room temperature. The XDC-2 degraded rice straw by 60.3% after fermentation for 15 days. Hemicelluloses were decomposed effectively, whereas the extracellular xylanase activity was dominant with an activity of 8.357 U/ml on day 6 of the fermentation period. The extracellular crude enzyme noticeably hydrolyzed natural lignocelluloses. The optimum temperature and pH for the xylanase activity were $40^{\circ}C$ and 6.0. However, the xylanase was activated in a wide pH range of 3.0-10.0, and retained more than 80% of its activity at $25-35^{\circ}C$ and pH 5.0-8.0 after three days of incubation in liquid culture under static conditions. PCR-DGGE analysis of successive subcultures indicated that the XDC-2 was structurally stable over long-term restricted and directed cultivation. Analysis of the 168 rRNA gene clone library showed that the XDC-2 was mainly composed of mesophilic bacteria related to the genera Clostridium, Bacteroides, Alcaligenes, Pseudomonas, etc. Our results offer a new approach to exploring efficient lignocellulolytic enzymes by constructing a high-performance composite microbial system with synergistic complex enzymes.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.585-591
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• 2014

To evaluate the potential utility of pretreatment of raw biomass with a complex microbial system, we investigated the degradation of rice straw by BMC-9, a lignocellulose decomposition strain obtained from a biogas slurry compost environment. The degradation characteristics and corresponding changes in the bacterial community were assessed. The results showed that rapid degradation occurred from day 0 to day 9, with a peak total biomass bacterium concentration of $3.3{\times}10^8$ copies/ml on day 1. The pH of the fermentation broth declined initially and then increased, and the mass of rice straw decreased steadily. The highest concentrations of volatile fatty acid contents (0.291 mg/l lactic acid, 0.31 mg/l formic acid, 1.93 mg/l acetic acid, and 0.73 mg/l propionic acid) as well as the highest xylanse activity (1.79 U/ml) and carboxymethyl cellulase activity (0.37 U/ml) occurred on day 9. The greatest diversity among the microbial community also occurred on day 9, with the presence of bacteria belonging to Clostridium sp., Bacillus sp., and Geobacillus sp. Together, our results indicate that BMC-9 has a strong ability to rapidly degrade the lignocelluloses of rice straw under relatively inexpensive conditions, and the optimum fermentation time is 9 days.

• 한국육종학회지
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• 제42권2호
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• pp.121-128
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• 2010

Finding alternative and renewable energy sources has become an important goal for plant scientists, especially with the demand for energy increasing worldwide and the supply of fossil fuel being depleted. The most important biofuel to date is bioethanol which is produced from sugars (sucrose and starch) found in corn and sugarcane. Second generation bioethanol is targeting studies that would allow the use of the cell wall (lignocellulose) as a source of carbon by non-food plants. Plant scientists, including breeders, agronomists, physiologists and molecular biologists, are working towards the development of new and improved energy crops especially, how to design crops for bioenergy production and increased biomass generation for biofuel purposes. This review focuses on: i) the current status of first generation bioenergy production, ii) the limitations of first and second generation bioenergy, and iii) ongoing research to overcome challenging issues in second generation bioenergy.

• 한국균학회지
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• 제22권3호
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• pp.254-259
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• 1994

P. chrysosporium BKM-F-1767 및 C. subvermispora FP90031-SP. 균사를 이용하여 ligninase와 laccase 활성제고를 위한 배앙방법을 검토한 결과는 다음과 같다. P. chrysosporium의 왕복진탕배양시 (150 rpm) 배양액량은 45-60 ml가 ligninase 활성제고에 적합하였으며 60 ml 배양은 최대활성 출현일이 빨리 나타났다. C. subvermispora의 정치배양시, 2% M.E.+0.1% Y.E.+0.1% T.W.20+1mMVA 처리에서 ligninase 활성이 가장 높았고 laccase의 활성은 2% M.E.+0.1% Y.E.+0.1% T.W.20+6 mMBA에서 최고 수준을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제31권10호
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• pp.1438-1445
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• 2021

A bifunctional glycoside hydrolase GH78 from the ascomycete Xylaria polymorpha (XpoGH78) possesses catalytic versatility towards both glycosides and esters, which may be advantageous for the efficient degradation of the plant cell-wall complex that contains both diverse sugar residues and esterified structures. The contribution of XpoGH78 to the conversion of lignocellulosic materials without any chemical pretreatment to release the water-soluble aromatic fragments, carbohydrates, and methanol was studied. The disintegrating effect of enzymatic lignocellulose treatment can be significantly improved by using different kinds of hydrolases and phenoloxidases. The considerable changes in low (3 kDa), medium (30 kDa), and high (> 200 kDa) aromatic fragments were observed after the treatment with XpoGH78 alone or with this potent cocktail. Synergistic conversion of rape straw also resulted in a release of 17.3 mg of total carbohydrates (e.g., arabinose, galactose, glucose, mannose, xylose) per gram of substrate after incubating for 72 h. Moreover, the treatment of rape straw with XpoGH78 led to a marginal methanol release of approximately 17 ㎍/g and improved to 270 ㎍/g by cooperation with the above accessory enzymes. In the case of beech wood conversion, the combined catalysis by XpoGH78 and laccase caused an effect comparable with that of fungal strain X. polymorpha in woody cultures concerning the liberation of aromatic lignocellulose fragments.

• 미생물학회지
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• 제51권3호
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• pp.209-220
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• 2015

목질 섭식 곤충에 관한 장내 세균 군집의 연구를 이용한 lignocellulose의 분해는 생명 공학적 응용에 있어 큰 잠재력을 갖는다. 본 연구에서 목질 섭식 곤충의 장내 세균 군집은 16S rRNA 유전자를 기반으로 한 파이로시퀀싱 방법을 이용하여 분석되었다. 분석된 모든 곤충에서 중장보다 후장에서 OTU수, 종 풍부도, 다양성 지수가 높았다. 세균 문 또는 강 수준의 다양성을 분석한 결과, 흰개미를 제외한 곤충의 장내 군집에는 Firmicutes, Bacteroidetes, ${\gamma}-Proteobacteria$가 우점하였다. PCoA (principal coordinates analysis)를 이용하여 세균의 군집 구조를 분석한 결과, 서식지보다는 곤충의 과별로 클러스터링 되는 경향이었다. CMC 분해 활성이 가장 높은 두 균주는 Bacillus toyonensis $BCT-7112^T$와 Lactococcus lactis subsp. hordniae $NCDO\;2181^T$과 유연관계가 높았다. 장 적출물의 섬유소 분해활성 실험 결과, 하늘소 후장에서 ${\beta}-1,4-glucosidase$, ${\beta}-1,4-endoglucanase$, ${\beta}-1,4-xylanase$의 효소활성이 가장 높았다. 본 연구에서는 목질 섭식 곤충의 장내에 다양하고 풍부한 세균이 서식하며, 섬유소를 분해하는 세균이 존재한다는 사실을 확인하였고, 이로부터 다양하고 유용한 섬유소 분해균을 분리할 수 있을 것으로 판단되었다.

• KSBB Journal
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• 제24권3호
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• pp.267-272
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• 2009

셀룰로오즈는 포도당 단위체가 $\beta$-1,4-glucoside결합을 이뤄 긴 사슬형태를 띈다. 또한 리그노셀룰오로직 물질에서의 셀룰로오즈 중 $50{\sim}90%$는 수소결합에 의해 결정형으로 존재하고 나머지 부분은 무정형으로 존재한다. 본 연구에서는 셀룰로오즈를 구성하는 포도당의 분해 생성물을 화인하기 위해 셀룰로오직 바이오매스 (유채대)와 1.5 g/l의 순수한 포도당을 반응온도 $164^{\circ}C$, 산 농도 0.77% (w/w) $H_2SO_4$, $0{\sim}20$ min동안 묽은 산 가수분해 시켜 분해물의 생성량 변화를 관찰하였다. 포도당을 묽은 산에 의해 분해시키면 탈수반응에 의해 1,6-anhydroglucose가 생성되며, 또한 포도당의 이성질체인 과당으로 전환되고 이 과당은 HMF와 포름산으로 전환된다. 또한 산 농도, 반응온도가 포도당 분해에 영향을 미치는 주요 변수임을 확인할 수 있었다. 그리고 분해생성물 중 하나인 HMF 1.308 g/l를 반응온도 $164^{\circ}C$, 산 농도 0.77% (w/w) $H_2SO_4$, $0{\sim}20$ min동안 산 가수분해 시켜 HMF와 HMF 분해물의 변화를 확인하였다.