• Journal of the Korean Society of Food Culture
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• v.33 no.6
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• pp.580-587
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• 2018

The baking properties of rice bread with polydextrose (3, 6, and 9%), enzymes (0.006, 0.009, and 0.018%) and egg (1.32 and 2.64%) were investigated. The specific gravity and color (L, a, b) of the dough, as well as the appearance, color (L, a, b) and texture of the rice bread were analyzed. The springiness, chewiness, gumminess (p<0.01) and hardness (p<0.001) of the rice bread tended to increase as the amount of added polydextrose increased. Replacement of rice flour with hemicellulase, glucose oxidase and fungal amylase are effective for producing rice bread. Replacement of rice flour with 0.009% glucose oxidase and 0.006% fungal amylase had a significant effect on increasing the volume and decreasing the hardness of the rice bread (p<0.001). Replacement of rice flour with 1.32% egg white also had a significant effect on increasing the volume and decreasing the hardness of the rice bread (p<0.001). These results suggest that replacement of rice flour with 0.009% glucose oxidase and 0.006% fungal amylase, and 1.32% egg white are effective for producing rice bread with good volume and hardness.

• Food Science and Biotechnology
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• v.14 no.4
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• pp.479-486
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• 2005

Arabinoxylan, a complex polysaccharide in cereal cell walls, has recently received research attention as a biological response modifier. The immunomodulating effect of arabinoxylans from rice bran (AXrb) was studied using a combined process of extrusion and commercial hemicellulase treatment in order to elucidate the augmentation mechanism of cell-mediated immunity in vitro. The cytotoxicity of mouse spleen lymphocytes against YAC-1 tumor cells was significantly enhanced by treatment with AXrb at $10-100\;{\mu}g/mL$. In an attempt to investigate the mechanism by which AXrb enhance NK cytotoxicity, we examined the effect of AXrb on cytokine production by spleen lymphocytes. Culture supernatants of the cells incubated with AXrb were collected and analyzed for IL-2 and IFN-${\gamma}$ synthesis by ELISA. IL-2 and IFN-${\gamma}$ production were increased significantly. These results suggest that AXrb may induce Th1 immune responses. Macrophages play an important role in host defenses against tumors by killing them and producing secretory products, which protect against bacterial, viral infection and malignant cell growth. AXrb were examined for their ability to induce secretory and cellular responses in murine peritoneal macrophages. When macrophages were treated with various concentrations ($10-100\;{\mu}g/mL$) of AXrb, AXrb induced tumoricidal activity, as well as increasing phagocytosis and the production of NO, $H_2O_2$, TNF-${\alpha}$, IL-$1{\beta}$, and IL-6. These results indicate that reactive oxygen species, reactive nitrogen species, and inflammatory cytokines are likely to be the major mediators of tumoricidal activity in AXrb-treated macrophages. Therefore, AXrb may be useful in cancer immunotherapy and it is anticipated that AXrb obtained using extrusion and subsequent enzyme treatment can be used as an ingredient in nutraceuticals and cereal-based functional food.

• BMB Reports
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• v.38 no.1
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• pp.17-23
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• 2005

During the screening of xylanolytic enzymes from locally isolated fungi, one strain BCC14405, exhibited high enzyme activity with thermostability. This fugal strain was identified as Aspergillus cf. niger based on its morphological characteristics and internal transcribed spacer (ITS) sequences. An enzyme with xylanolytic activity from BCC14405 was later purified and characterized. It was found to have a molecular mass of ca. 21 kDa, an optimal pH of 5.0, and an optimal temperature of $55^{\circ}C$. When tested using xylan from birchwood, it showed $K_m$ and $V_{max}$ values of 8.9 mg/ml and 11,100 U/mg, respectively. The enzyme was inhibited by $CuSO_4$, EDTA, and by $FeSO_4$. The homology of the 20-residue N-terminal protein sequence showed that the enzyme was an endo-1,4-$\beta$-xylanase. The full-length gene encoding endo-1,4-$\beta$-xylanase from BCC14405 was obtained by PCR amplification of its cDNA. The gene contained an open reading frame of 678 bp, encoding a 225 amino acid protein, which was identical to the endo-1,4-$\^{a}$-xylanase B previously identified in A. niger.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.171-171
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• 2011

리그노셀룰로오스 바이오매스를 원료로 하여 발효당을 생산하고자 할 때 최종적인 당수율은 적용하는 전처리 기술의 종류와 전처리 조건에 따라 크게 달라질 수 있다는 사실은 널리 알려져 있다. 또한 전처리물의 효소당화에서 셀룰로오스의 당전환율은 효소의 종류와 사용량에 의존적이므로 부족한 전처리 효과를 일부 보완하기도 한다. 본 연구에서는 바이오매스의 효소당화에 흔히 사용되고 있는 특정효소와 최근 공급되기 시작한 새로운 효소를 시료로 하여 해바라기 줄기의 열수전처리에 이은 효소당화에서 효소의 종류가 최종 당수율, 효소당화 시간 및 전처리효과에 미치는 영향을 측정하였다. 해바라기 줄기 분말을 $180^{\circ}C$에서 30분 동안 열수전처리하였을 때 헤미셀룰로오스의 수율이 최대가 되었으나 이 조건에서는 후속 효소당화에 의한 포도당 수율이 높지 않았다. Celluclast 1.5L 혹은 Celluclast conc BG는 전처리 물의 당화속도가 상대적으로 빠른 편이었고, 이 효소에 의한 당수율은 해바라기 줄기 셀룰로오스 함량의 80% 내외였으며, 바이오매스 1g당 효소첨가량이 3ml까지 증가함에 따라 당수율도 꾸준히 증가하는 경향을 보였다. 반면에 노보자임 스코리아로부터 분양받은 효소로서 NS22074와 NS50010의 혼합물은 Celluclast보다 약 10% 더 높은 당수율을 보여주었으나 당화는 상대적으로 느리게 진행되어 72시간 이상이 소요되었다. Endoxylanase 혹은 hemicellulase 등 다른 효소를 NS22074와 NS50010의 혼합물에 가하여도 당수율의 증대 효과는 미미하거나 거의 없었다. 시험에 사용한 효소제제에는 포도당, 소르비톨 등 여러 가지 당들이 보존제 혹은 안정화제로 함유되어 있는 것으로 나타나서 사용에 주의할 필요가 이었다.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.11
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• pp.1555-1565
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• 2009

Anaerobic rumen fungi have been regarded as good genetic resources for enzyme production which might be useful for feed supplements, bio-energy production, bio-remediation and other industrial purposes. In this study, an expressed sequence tag (EST) library of the rumen anaerobic fungus Neocallimastix frontalis was constructed and functional genes from the EST library were analyzed to elucidate carbohydrate metabolism of anaerobic fungi. From 10,080 acquired clones, 9,569 clones with average size of 628 bp were selected for analysis. After the assembling process, 1,410 contigs were assembled and 1,369 sequences remained as singletons. 1,192 sequences were matched with proteins in the public data base with known function and 693 of them were matched with proteins isolated from fungi. One hundred and fifty four sequences were classified as genes related with biological process and 328 sequences were classified as genes related with cellular components. Most of the enzymes in the pathway of glucose metabolism were successfully isolated via construction of 10,080 ESTs. Four kinds of hemi-cellulase were isolated such as mannanase, xylose isomerase, xylan esterase, and xylanase. Five $\beta$-glucosidases with at least three different conserved domain structures were isolated. Ten cellulases with at least five different conserved domain structures were isolated. This is the first solid data supporting the expression of a multiple enzyme system in the fungus N. frontalis for polysaccharide hydrolysis.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1322-1329
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• 2011

Filamentous fungi colonizing rice straw were collected from 11 different sites in Korea and were identified based on characterization of their morphology and molecular properties. The fungi were divided into 25 species belonging to 16 genera, including 14 ascomycetes, one zygomycete, and one basidiomycete. Fungal cellulolytic and xylanolytic enzymes were assessed through a two-step process, wherein highly active cellulase- and/or hemicellulase-producing fungi were selected in a first screening step followed by a second step to isolate the best enzyme-producer. Twenty-five fungal species were first screened for the production of total cellulase (TC), endo-${\beta}$-1,4 glucanase (EG), and endo-${\beta}$-1,4 xylanase (XYL) using solid-state fermentation with rice straw as substrate. From this screening, six species, namely, Aspergillus niger KUC5183, A. ochraceus KUC5204, A. versicolor KUC5201, Mucor circinelloides KUC6014, Trichoderma harzianum 1 KUC5182, and an unknown basidiomycete species, KUC8721, were selected. These six species were then incubated in liquid Mandels' media containing cellulose, glucose, rice straw, or xylan as the sole carbon source and the activities of six different enzymes were measured. Enzyme production was highly influenced by media conditions and in some cases significantly increased. Through this screening process, Trichoderma harzianum 1 KUC5182 was selected as the best enzyme producer. Rice straw and xylan were good carbon sources for the screening of cellulolytic and xylanolytic enzymes.

• Microbiology and Biotechnology Letters
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• v.11 no.1
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• pp.23-32
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• 1983

In the present study, two kinds of D-xylanases (1, 4-$\beta$-D-xylan xylanohydrolase (EC 3.2.1.8) were purified and characterized from crude extract of Aspergillus niger KG79. Xylanase I was most active at pH 5.0, whereas xylanse II at pH 4.0 Both enzymes demonstrated their maximum activity at 45$^{\circ}C$. They were relatively stable between pH 4.0 and 6.0 at 3$0^{\circ}C$ for 6 hours. Molecular weight of xylanse I and II were 12, 500 and 11, 500, respectively. Michaelis-Menten constants of xylanse I and II were 0.28% and 0.26% of xylan, respectively. Both enzymes could degrade commercial D-xylan to xylose, xylobiose, and xylotriose to the degree of about 10% of total reducing power. Xylanse I could, however, liberate arabinose from barley straw xylan in addition to xylose and xylooligasaccharides more rapidly than xylanase II. The degree of hydrolysis was about 25%. The reconstituted D-xylanase system with purified xylanases and $\beta$-xylosidase degraded commercial xylan and barley straw xylan to the degree of 28% and 54% respectively. The limit of hydrolysis by the enzymes was suggested to be resulted from the physical structure of the substrate.

• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1427-1437
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• 2014

Enzymatic hydrolysis of lignocellulosic biomass into fermentable sugars is a key step in the conversion of agricultural by-products to biofuels and value-added chemicals. Utilization of a robust microorganism for on-site production of biomass-degrading enzymes has gained increasing interest as an economical approach for supplying enzymes to biorefinery processes. In this study, production of multi-polysaccharide-degrading enzymes from Aspergillus aculeatus BCC199 by solid-state fermentation was improved through the statistical design approach. Among the operational parameters, yeast extract and soybean meal as well as the nonionic surfactant Tween 20 and initial pH were found as key parameters for maximizing production of cellulolytic and hemicellulolytic enzymes. Under the optimized condition, the production of FPase, endoglucanase, ${\beta}$-glucosidase, xylanase, and ${\beta}$-xylosidase was achieved at 23, 663, 88, 1,633, and 90 units/g of dry substrate, respectively. The multi-enzyme extract was highly efficient in the saccharification of alkaline-pretreated rice straw, corn cob, and corn stover. In comparison with commercial cellulase preparations, the BCC199 enzyme mixture was able to produce remarkable yields of glucose and xylose, as it contained higher relative activities of ${\beta}$-glucosidase and core hemicellulases (xylanase and ${\beta}$-xylosidase). These results suggested that the crude enzyme extract from A. aculeatus BCC199 possesses balanced cellulolytic and xylanolytic activities required for the efficient saccharification of lignocellulosic biomass feedstocks, and supplementation of external ${\beta}$-glucosidase or xylanase was dispensable. The work thus demonstrates the high potential of A. aculeatus BCC199 as a promising producer of lignocellulose-degrading enzymes for the biomass conversion industry.

• Journal of Microbiology and Biotechnology
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• v.30 no.11
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• pp.1670-1679
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• 2020

The substantial use of fungal enzymes to degrade lignocellulosic plant biomass has widely been attributed to the extensive requirement of powerful enzyme-producing fungal strains. In this study, a two-step screening procedure for finding cellulolytic fungi, involving a miniaturized culture method with shake-flask fermentation, was proposed and demonstrated. We isolated 297 fungal strains from several cellulose-containing samples found in two different locations in Thailand. By using this screening strategy, we then selected 9 fungal strains based on their potential for cellulase production. Through sequence-based identification of these fungal isolates, 4 species in 4 genera were identified: Aspergillus terreus (3 strains: AG466, AG438 and AG499), Penicillium oxalicum (4 strains: AG452, AG496, AG498 and AG559), Talaromyces siamensis (1 strain: AG548) and Trichoderma afroharzianum (1 strain: AG500). After examining their lignocellulose degradation capacity, our data showed that P. oxalicum AG452 exhibited the highest glucose yield after saccharification of pretreated sugarcane trash, cassava pulp and coffee silverskin. In addition, Ta. siamensis AG548 produced the highest glucose yield after hydrolysis of pretreated sugarcane bagasse. Our study demonstrated that the proposed two-step screening strategy can be further applied for discovering potential cellulolytic fungi isolated from various environmental samples. Meanwhile, the fungal strains isolated in this study will prove useful in the bioconversion of agricultural lignocellulosic residues into valuable biotechnological products.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1724-1730
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• 2012

An ${\alpha}$-L-arabinofuranosidase (TmAFase) from Thermotoga maritima MSB8 is a highly thermostable exo-acting hemicellulase that exhibits a relatively higher activity towards arabinan and arabinoxylan, compared with other glycoside hydrolase 51 family enzymes. In the present study, we carried out the enzymatic characterization and structural analysis of TmAFase. Tight domain associations found in TmAFase, such as an inter-domain disulfide bond (Cys306 and Cys476) in each monomer, a novel extended arm (amino acids 374-385) at the dimer interface, and total 12 salt bridges in the hexamer, may account for the thermostability of the enzyme. One of the xylan binding determinants (Trp96) was identified in the active site, and a region of amino acids (374-385) protrudes out forming an obvious wall at the substrate-binding groove to generate a cavity. The altered cavity shape with a strong negative electrostatic distribution is likely related to the unique substrate preference of TmAFase towards branched polymeric substrates.