• Journal of Microbiology and Biotechnology
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• 제2권3호
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• pp.197-203
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• 1992

Studies of the pretreatment of chitin and its subsequent hydrolysis by Aspergillus carneus chitinase are reported. Ball milling was found to be the most effective way among the pretreatment methods tested. Data are presented describing the effect of enzyme and substrate concentrations on the rate and extent of the hydrolysis process. It was found that the successive addition of enzyme improved the saccharification yield. Significant product inhibition of the chitinase was observed when N-acetylglucosamine concentration was 3.6％ or higher. Adsorption of enzymes to the substrate occurred during a 24 hr hydrolysis period. An initial rapid and extensive adsorption occurred, followed by gradual desorption which increased during the time of reaction. Intermediate removal of the hydrolyzate and continuation of the hydrolysis by adsorbed enzyme on the residual chitin was also investigated. A total of 75.4 g/l reducing sugars, corresponding to 69.2％ saccharificaton yield (as N-acetylglucosamine) was obtained. In addition an increase in the amount of recoverable enzymes was observed under these conditions. Evidence presented here suggests that the technique, whereby the free enzymes in the recovered hydrolyzate are re-adsorbed onto the new substrate, may provide a means of recirculating the dissolved enzymes.

• International Journal of Industrial Entomology and Biomaterials
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• 제48권2호
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• pp.67-77
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• 2024

This study aims to assess the efficacies of exogenous enzymes, derived from invertebrate gut-associated microbes, as feed additives, in reducing volatile organic compound (VOC) emissions using an in vitro pig intestine continuous fermentation system. An in vitro continuous fermentation model was used to simulate a comparable bionic digestion system by co-reacting feed, enzymatic additives (arazyme, mannanase, and xylanase, derived from the gut bacteria of Nephila clavata, Eisenia fetida, and Moechotypa diphysis, respectively), and gastrointestinal microbes, followed by an analysis of their correlations. A significant correlation was observed between exogenous enzyme supplementation and reduced VOC emissions in the fecal phase of continuous fermentation (p < 0.05). The concentration of VOCs decreased by 3.75 and 2.75 ppm in the treatment group following arazyme and multi-enzyme supplementation, respectively, compared to that in the control group (7.83 ppm). In addition, supplementation with arazyme and multiple enzymes significantly affected the microbial composition of each fermentation phase (p < 0.05). In particular, Lactiplantibacillus pentosus and Pediococcus pentosaceus, which changed in abundance according to arazyme or multi-enzyme supplementation, exhibited a positive relationship with VOC emissions. These results suggest that exogenous enzymes derived from invertebrate gut-associated bacteria can be efficiently applied as feed additives, leading to a reduction in VOC emissions.

• Journal of Microbiology and Biotechnology
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• 제21권2호
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• pp.192-196
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• 2011

Microbial induction of rusty-root was proved in this study. The enzymes hydrolyzing plant structural materials, including pectinase, pectolyase, ligninase, and cellulase, caused the rusty-root in ginseng. Pectinase and pectolyase produced the highest rusty-color formation. Ferrous ion ($Fe^{+++}$) caused the synergistic effect on rusty-root formation in ginseng when it was used with pectinase. The effect of ferric ion ($Fe^{++}$) on rusty-root formation was slow, compared with $Fe^{+++}$, probably due to gradual oxidation to $Fe^{+++}$. Other metal ions including the ferric ion ($Fe^{++}$) did not affect rusty-root formation. The endophytic bacteria Agrobacterium tumefaciens, Lysobacter gummosus, Pseudomonas veronii, Pseudomonas marginalis, Rhodococcus erythropolis, and Rhodococcus globerulus, and the rotten-root forming phytophathogenic fungus Cylindrocarpon destructans, caused rusty-root. The polyphenol formation (rusty color) was not significantly different between microorganisms. The rotten-root-forming C. destructans produced large quantities of external cellulase activity (${\approx}2.3$ U[${\mu}m$/min/mg protein]), which indicated the pathogenecity of the fungus, whereas the bacteria produced 0.1-0.7 U. The fungal external pectinase activities (0.05 U) and rusty-root formation activity were similar to those of the bacteria. In this report, we proved that microbial hydrolyzing enzymes caused rusty-root (Hue value $15^{\circ}$) of ginseng, and ferrous ion worsened the symptom.

• The Plant Pathology Journal
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• 제30권2호
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• pp.117-124
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• 2014

The plant pathogenic bacterial genus Pectobacteirum consists of heterogeneous strains. The P. carotovorum species is a complex strain showing divergent characteristics, and a new subspecies named P. carotovorum subsp. brasiliensis has been identified recently. In this paper, we re-identified the P. carotovorum subsp. brasiliensis isolates from those classified under the subspecies carotovorum and newly isolated P. carotovorum subsp. brasiliensis strains. All isolates were able to produce plant cell-wall degrading enzymes such as pectate lyase, polygalacturonase, cellulase and protease. We used genetic and biochemical methods to examine the diversity of P. carotovorum subsp. brasiliensis isolates, and found genetic diversity within the brasiliensis subsp. isolates in Korea. The restriction fragment length polymorphism analysis based on the recA gene revealed a unique pattern for the brasiliensis subspecies. The Korean brasiliensis subsp. isolates were divided into four clades based on pulsed-field gel electrophoresis. However, correlations between clades and isolated hosts or year could not be found, suggesting that diverse brasiliensis subsp. isolates existed.

• Journal of Applied Biological Chemistry
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• 제58권3호
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• pp.209-218
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• 2015

Fructooligosaccharides have been mainly produced by microbial fructosyltransferases (FTase) enzymes. The present work focuses on the optimization of medium composition and cultivation parameters affecting FTase produced by Penicillium aurantiogriseum AUMC 5605 in shake flask cultivation. FTase production was optimized in two steps using DeMeo's fractional factorial design. A 1.46-fold increase in FTase production (105.4 U/mL) was achieved using the optimized culture medium consisting of (g/L): sucrose, 600; yeast extract, 10; $K_2HPO_4$, 5; $MgSO_4{\cdot}7H_2O$, 0.5; $(NH_4)_2SO_4$, 1.0 and KCl, 0.5. The obtained results showed that the maximum FTase enzyme activity was produced at initial cultivation pH values ranging from 6.0-6.5, at agitation speed of 200 rpm and using vegetative fungal cells as inoculum. Moreover, results showed that optimization of medium composition and some cultivation parameters resulted in an increase of about 93.7% in the enzyme activity than the nonoptimized cultivation conditions after 96 h of cultivation. Additionally, maximum production and specific production rates recorded 2340 U/L/h and 102 U/L/h/g cells, respectively.

• 미생물학회지
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• 제53권4호
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• pp.323-325
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• 2017

Pectobacterium carotovorum subsp. actinidiae KKH3는 Enterobacteriaceae에 속하는 세균으로서, 키위 나무에 동고병과 같은 병을 일으키는 병원성 균주이다. 이 균주는 목본에서 분리되었으며 다양한 식물 세포벽 분해 효소를 가지고 있다. 따라서, 본 연구에서 제공하는 유전체 정보는 KKH3 균주의 병원성 기작을 이해하는 것뿐만 아니라 bioconversion 연구를 위한 토대로 활용될 수 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제33권7호
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• pp.1103-1112
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• 2020

Objective: To measure whether a microbial additive could effectively improve the fermentation quality of delayed-sealing (DS) silage, we studied the effects of inoculants of lactic acid bacteria (LAB) and cellulase enzyme on microbial populations, ensiling characteristics, and spoilage loss of DS silage of Napier grass in Africa. Methods: Quick-sealing (QS) and DS silages were prepared with and without LAB (Lactobacillus plantarum) inoculant, cellulase enzymes, and their combination. The QS material was directly chopped and packed into a bunker silo. The DS material was packed into the silo with a delay of 24 h from harvest. Results: In the QS silage, LAB was dominant in the microbial population and produced large amounts of lactic acid. When the silage was treated with LAB and cellulase, the fermentation quality was improved. In the DS silage, aerobic bacteria and yeasts were the dominant microbes and all the silages were of poor quality. The yeast and mold counts in the DS silage were high, and they increased rapidly during aerobic exposure. As a result, the DS silages spoiled faster than the QS silages upon aerobic exposure. Conclusion: DS results in poor silage fermentation and aerobic deterioration. The microbial additive improved QS silage fermentation but was not effective for DS silage.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.724-735
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• 2023

NdgR, a global regulator in soil-dwelling and antibiotic-producing Streptomyces, is known to regulate branched-chain amino acid metabolism by binding to the upstream region of synthetic genes. However, its numerous and complex roles are not yet fully understood. To more fully reveal the function of NdgR, phospholipid fatty acid (PLFA) analysis with gas chromatography-mass spectrometry (GC-MS) was used to assess the effects of an ndgR deletion mutant of Streptomyces coelicolor. The deletion of ndgR was found to decrease the levels of isoleucine- and leucine-related fatty acids but increase those of valine-related fatty acids. Furthermore, the defects in leucine and isoleucine metabolism caused by the deletion impaired the growth of Streptomyces at low temperatures. Supplementation of leucine and isoleucine, however, could complement this defect under cold shock condition. NdgR was thus shown to be involved in the control of branched-chain amino acids and consequently affected the membrane fatty acid composition in Streptomyces. While isoleucine and valine could be synthesized by the same enzymes (IlvB/N, IlvC, IlvD, and IlvE), ndgR deletion did not affect them in the same way. This suggests that NdgR is involved in the upper isoleucine and valine pathways, or that its control over them differs in some respect.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.892-896
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• 2003

High-level expression of the lipase B26 gene from Bacillus pumilus was achieved using Bacillus subtilis Chungkookjang isolated from the Korean traditional fermented bean paste, Chungkookjang. For the secretory production of recombinant lipase B26 in a Bacillus host system, pLipB26 was constructed by ligating the lipase B26 gene into the recently designed Escherichia coli-Bacillus shuttle vector, pLipSM, and that was then transformed into B. subtilis Chungkookjang. Among the various vector, medium, and host combinations, B. subtilis Chungkookjang harboring the pLipB26 exhibited the highest lipase activity in PY medium, and B. subtilis Chungkookjang secreted two times more enzymes than B. subtilis DB 104 under the same condition. When B. subtilis Chungkookjang harboring the pLipB26 was cultured in a 5-1 jar-fermentor containing 21 of a PY medium, the maximum lipase activity (140 U/ml) and production yield (0.68 g/l) were obtained during the late exponential phase from a cell-free culture broth. Although B. subtilis Chungkookjang also secreted extracellular proteases at the late exponential phase, these results suggested the potential of B. subtilis Chungkookjang as a host for the secretory production of foreign proteins.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.95.1-95
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• 2003

Plant growth promoting rhizobacteria (PGPR) have been shown to suppress phytopthora blight. This suppression has been related to both microbial antagonism and induced resistance. The PGPR isolates were screened by dual culture plate method and most of the isolates were showed varying levels of antagonism. Among the PGPR isolates pyoverdin, pyochelin and salicylic acid producing strains showed the maximum inhibition of mycelial growth of Phytopkhora capsici and increased plant growth promotion in red pepper. PGPR isolates further analysed for its ability to induce production of defence related enzymes and chemicals. The activities such as Phenyle alanin ammonia Iyase (PAL), Peroxidase (PO), Polyphenol oxidase (PPO) and accumulation of phenolics were observed in PGPR pretreated red pepper plants challenged with Phytopkhora capsici. The present study shows that an addition of direct antagonism and plant growth promotion, induction of defense related enzymes involved to enhance resistance against invasion of P. capsici in red pepper.