• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.3
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• pp.79-89
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• 2011

The wasted corn stalk from Gangwon province is composed of 44.6 % glucan, 19.0 % xylan, 23.8 % lignin, 4.5 % ash and 8.1 % others. Statistical analysis, full factorial design, revealed that temperature was the most influential factor in the dilute sulfuric acid pretreatment and that the influence of temperature on xylose yield was 3.5 and 3.2 times higher than those of treatment time and acid concentration, respectively. Temperature was also the most influential factor for glucose yield in the pretreatment but it was less than 5 % throughout the pretreatment. Although minor sugar yield was observed when microwave or ultrasonication was solely introduced as a pretreatment method, the complex method incorporating microwave or ultrasonication into dilute sulfuric acid pretreatment enhanced sugar yield significantly. In particular, xylose yield was doubled when microwave and dilute sulfuric acid treatment was sequentially applied. The optimization of pretreatment and enzymatic hydrolysis as well as the investigation on the complex pretreatment in detail are left for further study.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.806-811
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• 2016

Organosolv pretreatment is the process to frationation of lignocellulosic feedstocks to enhancement of enzymatic hydrolysis. This process has advantages that organic solvents are always easy to recover by distillation and recycled for pretreatment. The chemical recovery in organosolv pretreatment can isolate lignin as a solid material and carbohydrates as fermentable sugars. For the economic considerations, using of low-molecular-weight alcohols such as ethanol and methanol have been favored. When acid catalysts are added in organic solvent, the rate of delignification could be increased. Mineral acids (hydrochloric acid, sulfuric acid, and phosphoric acid) are good catalysts to accelerate delignification and xylan degradation. In this study, the biomass was pretreated using 40~50 wt% ethanol at $170{\sim}180^{\circ}C$ during 20~60 min. As a results, the enzymatic digestibility of 2-stage pretreatment of rigida using 50 wt% ethanol at $180^{\circ}C$ was 40.6% but that of 1-stage pretreatment was 55.4% on same conditions, therefore it is shown that the pretreatment using mixture of the organosolv and catalyst was effective than using them separately.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.108-117
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• 2017

Laver, Porphyra, is distinctive for its high content of proteins and polysaccharides such as porphyran and hemicellulose. The chemical properties of the polysaccharides extracted with different extraction methods such as hot water, dilute acid(pH 4.0) or alkali solution(2N NaOH) were examined to investigate the suitable extraction conditions for porphyran and hemicellulose from laver. For porphyran extraction, dilute acid solution was more preferable to hot water and alkali solution because of its higher 3,6-anhydrogalactose content and lower protein content. However, alkali solution was more suitable to extract the hemicellulose because of higher mannose content indicating the extraction of mannan. To decrease contamination of the polysaccharides with protein, the dried lavers were pretreated with enzymes (Protamex, Flavourzyme, Alcalase, Viscozyme) before hot water extraction. All enzyme pretreatments increased the yield of polysaccharides by compared with control (enzyme unpretreated) and Flavourzyme pretreatment was most effective to decrease protein contamination in the polysaccharide. All viscosities of porphyran solutions pretreated by enzymes were lower compared to the control porphyran solution and showed pseudoplastic behavior with yield stress. In case of alkali extraction of residues obtained after enzyme hydrolysis and hot water extraction, protease pretreatment increased the mannose contents in the polysaccharide while the xylose content was increased by Viscozyme pretreatment.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.336-343
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• 2016

A mannanase gene was cloned into Escherichia coli from Cellulosimicrobium sp. YB-43, which had been found to produce two kinds of mannanase, and sequenced completely. This mannanase gene, designated manB, consisted of 1,284 nucleotides encoding a polypeptide of 427 amino acid residues. Based on the deduced amino acid sequence, the ManB was identified to be a modular enzyme including two carbohydrate binding domains besides the catalytic domain, which was highly homologous to mannanases belonging to the glycosyl hydrolase family 5. The N-terminal amino acid sequence of ManB, purified from a cell-free extract of the recombinant E. coli carrying a Cellulosimicrobium sp. YB-43 manB gene, has been determined as QGASAASDG, which was correctly corresponding to signal peptide predicted by SignalP4.1 server for Gram-negative bacteria. The purified ManB had a pH optimum for its activity at pH 6.5~7.0 and a temperature optimum at $55^{\circ}C$. The enzyme was active on locust bean gum (LBG), konjac and guar gum, while it did not exhibit activity towards carboxymethylcellulose, xylan, starch, and para-nitrophenyl-${\beta}$-mannopyranoside. The activity of enzyme was inhibited very slightly by $Mg^{2+}$, $K^+$, and $Na^+$, and significantly inhibited by $Cu^{2+}$, $Zn^{2+}$, $Mn^{2+}$, and SDS. The enzyme could hydrolyze mannooligosaccharides larger than mannobiose, which was the most predominant product resulting from the ManB hydrolysis for mannooligosaccharides and LBG.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.414-422
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• 2022

The objective of this work was to investigate the feasibility of acid-catalyzed hydrothermal fractionation for maximum solubilization of the hemicellulosic portion of two typical agricultural residues. The fractionation conditions converted into combined reaction severity (CS) in the range of 1.2-2.9 was used to establish a simple reaction criteria at glance. The hemicellulosic sugar yield of 56.6% was shown when rice straw was fractionated at the conditions at the conditions; 160 ℃ of temperature 0.75% (w/v) of H₂SO₄, 20 min of reaction time, 1:15 solid/liquid ratio. The hemicellulosic sugar yield of 83.0%, however, was achieved when barley straw was fractionated at the conditions at the conditions; 150 ℃ of temperature 0.75% (w/v) of H₂SO₄, and 15 min of reaction time, 1:10 solid/liquid ratio. For barley straw, acid-catalyzed hydrothermal fractionation could be effectively performed. After the fractionation process, the remaining fractionated solids were 48.5% and 57.5% from raw rice and barley straws, respectively. The XMG contents in the solid residues decreased from 17.3% and 17.6% to 6.0% and 2.6%, which corresponded to 16.7% and 8.5% on the basis of the raw straws, respectively. In another way, only 5.6% of cellulose and 8.5% of XMG were lost due to excessive decomposition during the acid-catalyzed hydrothermal fractionation of barley straw, compared to cellulose and XMG losses of 6.4% and 26.6% in rice straw. Hemicellulosic sugars from the rice straw were considered more over-decomposed due to the somewhat higher reaction severity at the acid-catalyzed hydrothermal fractionation.