• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.749-760
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• 2022

α-Galactosidase is a debranching enzyme widely used in the food, feed, paper, and pharmaceuticals industries and plays an important role in hemicellulose degradation. Here, T26, an aerobic bacterial strain with thermostable α-galactosidase activity, was isolated from laboratory-preserved lignocellulolytic microbial consortium TMC7, and identified as Parageobacillus thermoglucosidasius. The α-galactosidase, called T26GAL and derived from the T26 culture supernatant, exhibited a maximum enzyme activity of 0.4976 IU/ml when cultured at 60℃ and 180 rpm for 2 days. Bioinformatics analysis revealed that the α-galactosidase T26GAL belongs to the GH36 family. Subsequently, the pET-26 vector was used for the heterologous expression of the T26 α-galactosidase gene in Escherichia coli BL21 (DE3). The optimum pH for α-galactosidase T26GAL was determined to be 8.0, while the optimum temperature was 60℃. In addition, T26GAL demonstrated a remarkable thermostability with more than 93% enzyme activity, even at a high temperature of 90℃. Furthermore, Ca²⁺ and Mg²⁺ promoted the activity of T26GAL while Zn²⁺ and Cu²⁺ inhibited it. The substrate specificity studies revealed that T26GAL efficiently degraded raffinose, stachyose, and guar gum, but not locust bean gum. This study thus facilitated the discovery of an effective heat-resistant α-galactosidase with potent industrial application. Meanwhile, as part of our research on lignocellulose degradation by a microbial consortium, the present work provides an important basis for encouraging further investigation into this enzyme complex.

• 농업과학연구
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• 제43권1호
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• pp.127-135
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• 2016

Improving farming activity competence of farm households has recently been considered one of the most important factors for increasing farm income. However, few studies examine the relationship between farm income and farming activity competence of farm households directly due to the lack of an available dataset. In this study, we examine the relationship between farm household technical managerial competence and farm household income based on the nearly 30,000 farm households consulting data gathered by the Rural Development Administration, RDA. The major findings of this study are as follows: firstly, statistically significant differences in agricultural and farm household income exist between farm households categorized by farm activity competence levels in terms of technique and management. Secondly, a technically and managerially competent farm household group (high-rank farm household) has 2.2 times higher agricultural income and 1.9 times higher farm household income than the technically and managerially incompetent farm household group (low-rank farm household). Thirdly, farm household technical-managerial competence is one of the major factors that affect agricultural and farm household income. Regarding technical competence, agricultural income and farm household income increased by approximately 1,390,000 won and 1,530,000 won, respectively, as technical points increased by one point. However, with respect to managerial competence, agricultural income and farm household income increased by approximately 1,320,000 won and 2,070,000 won, respectively, as managerial points increased by one point.

• Journal of Applied Biological Chemistry
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• 제48권4호
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• pp.187-192
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• 2005

Influence of herbicide oxadiazon on soil microbial activity and nitrogen dynamics was evaluated. Soil samples were treated with oxadiazon at field and tenfold field rates and incubated. Organic amendment was added as an additional substrate for soil microorganisms. Tenfold field rate oxadiazon stimulated substrate-induced respiration (SIR) and dehydrogenase activity (DHA) in amended soil as compared to unamended soil and control treatment. Soil urease activity was not affected by oxadiazon treatment. In both amended and unamended soils, treatment of the herbicide at higher rate had not significant influence on $NH_4$-N and $NO_3$-N concentrations. Higher dose of oxadiazon was degraded in both soils, but dissipation rate in amended soil was higher than unamended soil, with half-lives ($t_{1/2}$) of 23.1 and 138.6 days, respectively. Recommended field rate did not affect microbial activity and nitrogen dynamics in soil ecosystem. Results showed influence of oxadiazon on cycling processes of nitrogen in soil was not significant however its effect on microbial activity was a tendency depending on addition of organic amendment to soil.

• 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.

• 한국식품영양학회지
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• 제34권4호
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• pp.398-406
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• 2021

This study investigated on the nutritional components and physiological activity of four wild vegetables namely Salvia plebeia R. Br., Angelica acutiloba, Gynura procumbens and Saururus chinensis Baill for the development of representative wild vegetables in Chungbuk. Salvia plebeia possessed the highest radical scavenging activity and beta-carotene, but exhibited the lowest α-glucosidase inhibitory activity compared to the other three vegetables. Angelica acutiloba showed high crude protein content and α-glucosidase inhibitory activity, but contained low total polyphenol content, radical scavenging ability and beta-carotene compared to the other three vegetables. Gynura procumbens showed high mineral content, beta-carotene, vitamin K1 content and α-glucosidase inhibitory activity, but showed the lowest total polyphenol content and radical scavenging ability compared to the other three vegetables. Saururus chinensis showed high crude fiber content and total polyphenol content, but contained the lowest mineral and vitamin K1 content. To conclude, it is suggested to use Salvia plebeia or Saururus chinensis as antioxidant food materials and Angelica acutiloba and Gynura procumbens as food materials and sources of α-glucosidase inhibitors. In particular, it is believed that Saururus chinensis, which possessed high content of crude fiber, is suitable for low-calorie food materials such as diet products.

• International Journal of Industrial Entomology and Biomaterials
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• 제26권2호
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• pp.89-94
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• 2013

Entomopathogenic fungal species have been investigated for their potential use as biological control agents owing to their natural role as insect pathogens. These fungi produce a wide range of secondary metabolites with high therapeutic values, such as antibiotics and cytotoxic substances. To evaluate the antibacterial activity of entomopathogenic fungi, 10 isolates from Korean soil were selected and tested for their activity against Escherichia coli by using fungal culture filtrates. Antibacterial activity was assessed using a two-step process: (1) a screening assay for the selection of fungal isolates and (2) a quantitative assay to evaluate the activity of select fungi. Although 4 fungal isolates were selected through the screening assay, only 3 fungal isolates, from Beauveria bassiana and Metarhizium anisopliae, showed high antibacterial activity according to the quantitative assay. The antibacterial activity of selected fungal culture filtrates was stable when exposed to heat and proteolytic enzyme treatments, which indicated that the antibacterial compound is not a protein. These entomopathogenic fungal metabolites might be useful as a source for bacterial control and in the pharmaceutical industry.

• International Journal of Industrial Entomology and Biomaterials
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• 제33권2호
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• pp.78-84
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• 2016

The antioxidant activity of silkworm powder treated by proteolytic enzyme was investigated. Total protein content of silkworm power was assayed using BCA, Bradford assays and SDS-polyacrylamide gel electrophoresis (PAGE) with alkaline protease treatment conditions including temperature and pH. The optimum condition of alkaline protease treatment for silkworm powder was found to be $60^{\circ}C$ and pH 7. The alkaline protease treatment resulted in increased contents of free amino acids, total polyphenol and total flavonoid compared to control group. The silkworm hydrolysates showed excellent antioxidant activities in various in vitro models such as 2,2 diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2 - azino-bis(3-ethylbenzthiazoline-6)-sulfonic acid (ABTS) radical scavenging activity. These results provide useful information for using silkworm powder as an ingredient in functional foods and for exploiting alkaline protease treatment to improve the extractability and bioactivity of a raw material.

• The Plant Pathology Journal
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• 제28권1호
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• pp.10-19
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• 2012

This study investigated the distribution of endophytic fungi obtained from the surface sterilized tissues of leaves, stems and roots of chili pepper ($Capsicum$ $annuum$ L.) plants in seedling, flowering and fruiting stages in Korea and their antifungal activity. A total of 481 isolates were recovered and were identified using molecular techniques. Based on rDNA ITS gene sequence and phylogenetic analysis, 21 fungal genera were characterized, belonging to 16 Ascomycota and 5 Basidiomycota. $Penicillium$ in seedling stage, $Fusarium$ in flowering stage, $Colletotrichum$ followed by $Fusarium$, $Alternaria$ and $Xylaria$ in fruiting stage was predominant and $Alternaria$, $Cladosporium$ and $Fusarium$ were common in all growth stages. Among 481 endophytes 90 phenotypes were evaluated for the antimicrobial activity against three major pathogens ($Phytophthora$ $capsici$, $Colletotrichum$ $acutatum$ and $Fusarium$ $oxysporum$) of chili pepper. Among them 16 isolates inhibited the growth of at least one test microorganisms. Three strains showed a broad spectrum antifungal activity and displayed strong inhibition against chili pepper pathogenic fungi.

• Journal of Plant Biotechnology
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• 제38권4호
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• pp.272-277
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• 2011

Plants expressing Agrobacterium sp. strain CP4 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) are known to be resistant to glyphosate, a potent herbicide that inhibits the activity of the endogenous plant EPSPS. In order to develop herbicide-resistant rice, we prepared transgenic rice plants with CP4 EPSPS gene under the control of CaMV 35S promoter for over-expression. A recombinant plasmid was transformed into rice via Agrobacterium-mediated transformation. A large number of transgenic rice plants were obtained with glyphosate and most of the transformants showed fertile. The integration and expression of CP4 EPSPS gene from regenerated plants was analyzed by Southern and northern blot analysis. The transgenic rice plants had CP4 EPSPS enzyme activity levels more than 15-fold higher than the wild-type plants. EPSPS enzyme activity of transgenic rice plants was also identified by strip-test method. Field trial of transgenic rice plants further confirmed that they can be selectively survived at 100% by spay of glyphosate (Roundup$^{(R)}$) at a regular dose used for conventional rice weed control.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.450-456
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• 2006

Pseudomonas fluorescens MC07 is a growth-promoting rhizobacterium that suppresses mycelial growth in fungi such as Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Phytophthora capsici. To determine the role of the bacterium's antifungal activity in disease suppression, we screened 2,500 colonies generated by Tn5lacZ insertions, and isolated a mutant 157 that had lost antifungal activity. The EcoRI fragment carrying Tn5lacZ was cloned into pBluescript II SK(+) and used as a probe to isolate wild-type clones from a genomic library of the parent strain, MC07. Two overlapping cosmid clones, pEH4 and pEH5, that had hybridized with the mutant clone were isolated. pEH4 conferred antifungal activity to the heterologous host P.fluorescens strain 1855.344, whereas pEH5 did not. Through transposon mutagenesis of pEH4 and complementation analyses, we delineated the 14.7-kb DNA region that is responsible for the biosynthesis of an antifungal compound. DNA sequence analysis of the region identified 11 possible open reading frames (ORF), ORF1 through ORF11. A BLAST search of each putative protein implied that the proteins may be involved in an antifungal activity similar to polyketides.