• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.127.1-127.1
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• 2007

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• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.122-125
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• 2022

The cellulose-fed microbial fuel cell (MFC) is a biotechnological process that directly converts lignocellulosic materials to electricity without combustion. In this study, the cellulose-fed, MFC-integrated thermophilic bacterium, Bacillus sp. WK21, with endoglucanase and exoglucanase activities of 1.25 ± 0.08 U/ml and 0.95 ± 0.02 U/ml, respectively, was used to generate electricity at high temperatures. Maximal current densities of 485, 420, and 472 mA/m² were achieved when carboxymethyl cellulose, avicel cellulose, and cellulose powder, respectively, were used as substrates. Their respective maximal power was 94.09, 70.56, and 89.30 mW/m³. This study demonstrates the value of the novel use of a cellulase-producing thermophilic bacterium as a biocatalyst for electricity generation in a cellulose-fed MFC.

• Korean Journal of Microbiology
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• v.51 no.3
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• pp.209-220
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• 2015

In this study, gut bacterial communities in xylophagous insects were analyzed using the pyrosequencing of 16S rRNA genes for their potential biotechnological applications in lignocelluloses degradation. The result showed that operational taxonomic units (OTUs), species richness and diversity index were higher in the hindgut than in the midgut of all insect samples analyzed. The dominant phyla or classes were Firmicutes (54.0%), Bacteroidetes (14.5%), ${\gamma}-Proteobacteria$ (12.3%) in all xylophagous insects except for Rhinotermitidae. The principal coordinates analysis (PCoA) showed that the bacterial community structure mostly clustered according to phylogeny of hosts rather than their habitats. In our study, the two carboxymethyl cellulose (CMC)-degrading isolates which showed the highest enzyme activity were most closely related to Bacillus toyonensis $BCT-7112^T$ and Lactococcus lactis subsp. hordniae $NCDO\;2181^T$, respectively. Cellulolytic enzyme activity analysis showed that ${\beta}-1,4-glucosidase$, ${\beta}-1,4-endoglucanase$ and ${\beta}-1,4-xylanase$ were higher in the hindgut of Cerambycidae. The results demonstrate that xylophagous insect guts harbor diverse gut bacteria, including valuable cellulolytic bacteria, which could be used for various biotechnological applications.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.91-99
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• 2007

Activities of the extracellular enzyme from Fomitopsis palustris, a brown-rot fungi, and by which crystallinity changes of cellulose in the various softwoods, such as Larix leptolepsis, Finns rigida, Finns koraiensis and Finns densiflora by liquid culture, were investigated. Activity of Cellobiohydrolase (CBH) from F. palustris was detected in the every test softwoods culture, showing activities of the Endoglucanase (EG), $\beta$-glucosidase (BGL) and $\beta$-1,4-xylosidase (BXL). It was shown high enzyme activities in the sapwood culture than heartwood of the same wood species, However, the enzyme activities in most of test wood cultures increased with longer incubation time, indicating a possibility of intermix sapwood and heartwood for degradation process by enzyme. Also it was shown that protein patterns of the extracellular enzyme from F. palustris in wood particle substrate of the several domestic softwoods were similar with each other wood species, which suggested the possibility of mixing all softwoods in saccharification by enzyme from F. palustris. Crystallinity reduction value of cellulose by F. palustris was 4.2~20.4% in 4 weeks cultivation, 12.9~28.9% in 8 weeks.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.68-74
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• 2015

Based on the genomic analysis of Thermococcus pacificus P-4, we identified a putative GH1 ${\beta}$-glucosidase-encoding gene (Tpa-glu). The gene revealed a 1,464 bp encoding 487 amino acid residues, and the deduced amino acid residues exhibited 77% identity with Pyrococcus furiosus ${\beta}$-glucosidase (accession no. NP_577802). The gene was cloned and expressed in Escherichia coli system. The recombinant protein was purified by metal affinity chromatography and characterized. Tpa-Glu showed optimum activity at pH 7.5 and $75^{\circ}C$, and thermostability with a half life of 6 h at $90^{\circ}C$. Tpa-Glu exhibited hydrolyzing activity against various pNP-glycopyranosides, with kcat/Km values in the order of pNP-${\beta}$-glucopyranoside, pNP-${\beta}$-galactopyranoside, pNP-${\beta}$-mannopyranoside, and pNP-${\beta}$-xylopyranoside. In addition, the enzyme exhibited exo-hydrolyzing activity toward ${\beta}$-1,3-linked polysaccharide (laminarin) and ${\beta}$-1,3- and ${\beta}$-1,4-linked oligosaccharides. This is the first description of an enzyme from hyperthermophilic archaea that displays exo-hydrolyzing activity toward ${\beta}$-1,3-linked polysaccharides and could be applied in combination with ${\beta}$-1,3-endoglucanase for saccharification of laminarin.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.77-83
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• 1999

Molecular biological techniques that recently developed, have made it possible to realize some of new attempts in the research field of rumen microbiology. Those are 1) cloning of genes from rumen microorganisms mainly in E. coli, 2) transformation of rumen bacteria and 3) ecological analysis with nonculturing methods. Most of the cloned genes are for polysaccharidase enzymes such as endoglucanase, xylanase, amylase, chitinase and others, and the cloning rendered gene structural analyses by sequencing and also characterization of the translated products through easier purification. Electrotransformation of Butyrivibrio fibrisolvens and Prevotella ruminicola have been made toward the direction for obtaining more fibrolytic, acid-tolerant, depoisoning or essential amino acids-producing rumen bacterium. These primarily required stable and efficient gene transfer systems. Some vectors, constructed from native plasmids of rumen bacteria, are now available for successful gene introduction and expression in those rumen bacterial species. Probing and PCR-based methodologies have also been developed for detecting specific bacterial species and even strains. These are much due to accumulation of rRNA gene sequences of rumen microbes in databases. Although optimized analytical conditions are essential to reliable and reproducible estimation of the targeted microbes, the methods permit long term storage of frozen samples, providing us ease in analytical work as compared with a traditional method based on culturing. Moreover, the methods seem to be promissing for obtaining taxonomic and evolutionary information on all the rumen microbes, whether they are culturable or not.

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.49-55
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• 1994

A fungal strain capable of producing extracellular cellulase was isolated from farmland. It was identified as Aspergillus niger, and named Aspergillus niger KKS. Production of cellulase and xylanase by the A. niger KKS was studied through a shake-flask culture. The effects of culture conditions such as inoculum size, temperature, pH, and medium composition on the cellulase and xylanase production were examined. The optimum temperature and pH for the enzyme production were $30^{\circ}C$ and pH 7.0, respectively. The optimized medium was composed of 2.0% (w/v) rice straw, 0.5% (w/v) proteose peptone, 0.5% (w/v) $KH_2 PO_4$, 0.05% (w/v) yeast extract, 0.01% (w/v) $CoSO_4 \cdot 7H_2O$, and 0.05% (w/v) $CuSO$_4$\cdot 5H_2O$. When the strain was incubated with the optimized medium, it gave the activities of endoglucanase, $\beta$-glucosidase, $\beta$-xylosidase, xylanase were 3.80, 4.20, 4.00, 80.0 (IU/mL), respectively. Filter paper and cotton activities were 0.68 and 0.045 (IU/mL), respectively. The results of this study show that A. niger KKS is a potential organism with a wide spectrum of enzyme activities, such as those of $\beta$-glucosidase, $\beta$-xylosidase, and xylanase.

• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1118-1126
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• 2012

Four putative GH12 genes were found in the Fusarium graminearum genome. The corresponding proteins were expressed in Escherichia coli, purified, and evaluated. FGSG_05851 and FGSG_11037 displayed high activities towards xyloglucan ($V_{max}$ of 4 and $11{\mu}mol/min$, respectively), whereas FGSG_07892 and FGSG_16349 were much less active with this substrate (0.081 and $0.004{\mu}mol/min$, respectively). However, all four of these enzymes had a similar binding affinity for xyloglucan. Xyloglucan was the substrate preferred by FGSG_05851, in contrast to the three other enzymes, which preferred ${\beta}$-glucan or lichenan. Therefore, FGSG_05851 is a xyloglucan-specific glucanase (E.C. 3.2.1.151) rather than an endoglucanase (E.C. 3.2.1.4) with broad substrate specificity. FGSG_11037 displayed a peculiar behavior in that the xyloglucan binding was highly cooperative, with a Hill coefficient of 2.5. Finally, FGSG_05851 essentially degraded xyloglucan into hepta-, octa-, and nonasaccharides, whereas the three other enzymes yielded hepta- and octa-saccharides as well as larger molecules.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1101-1107
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• 2015

The role of CRE1 in a thermophilic fungus, Myceliophthora thermophila ATCC42464, was studied using RNA interference. In the cre1-silenced strain C88, the filter paper hydrolyzing activity and β-1,4-endoglucanase activity were 3.76-, and 1.31-fold higher, respectively, than those in the parental strain when the strains were cultured in inducing medium for 6 days. The activities of β-1,4-exoglucanase and cellobiase were 2.64-, and 5.59-fold higher, respectively, than those in the parental strain when the strains were cultured for 5 days. Quantitative reverse-transcription polymerase chain reaction showed that the gene expression of egl3, cbh1, and cbh2 was significantly increased in transformant C88 compared with the wild-type strain. Therefore, our findings suggest the feasibility of improving cellulase production by modifying the regulator expression, and an attractive approach to increasing the total cellulase productivity in thermophilic fungi.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.505-510
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• 1992

An endo-$\beta$-1,4-glucanase gene of Clostridium thermocellum was cloned in Escherichia coli and was considered as a novel gene by comparison with the restriction patterns of the C. thermocellum cellulase genes so far reported. The endoglucanase from recombinant E. coli was purified by column chromatography after heat treatment. The purified enzyme was a monomer having molecular weight of 40,000. The enzyme hydrolyzed CMC to glucose and cello-oligosaccharides at :naximum activities at pH 5.0 and $65^{\circ}C$. One of the endproducts, glucose, showed no inhibitory effect on the enzyme activity, while the other endproduct, cellobiose, inhibited slightly. The values of $K_{m}$ and $V_{max}$ of the enzyme for CMC were 0.39% (w/v) and 268 Ulmg protein, respectively.