• Microbiology and Biotechnology Letters
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• 제19권5호
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• pp.464-469
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• 1991

An $\alpha$-amylase producing bacterium, strain 2B, was isolated from soil and identified to genus Bacillus. To enhance $\alpha$-amylase productivity, strain 2B was mutagenized successively with nitrosoguanidine. For an efficient selection of a-amylase hyperproducers, mutants which produced $\alpha$-amylase in the presence of glucose were isolated. The resultant mutant HG4, which was classified as constitutive and catabolite derepressed hyperproducer of a-amylase, produced about 30 folds more $\alpha$-amylase than parental strain in medium containing lactose as carbon source. The strain HG4 grew rapidly and produced enzyme in parallel with cell growth. Moreover, its cell lysis did not occur until time of maximal yield of enzyme, which was considered to be a favorable characteristic for the production and purificiation of enzyme in industrial scale. The enzymatic properties of parental strain 2B and mutant strain HG4 were almost the same. The optimal temperature and pH for enzyme reaction was $70^{\circ}C$ and pH 6.0, respectively, in 'the presence of 0.6mM $Ca^[2+}$ as an effective stabilizer.

• Korean Journal of Microbiology
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• 제23권2호
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• pp.77-83
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• 1985

The aim of this investigation was to resolve the contradiction between the results of Sternberg and Mandels (1980, 1982)and those of Nisizawa et al., (1971) in cellulase induction by sophorose, and furthermore to study the conditional effects in sophorose-induced cellulase induction in Trichoderma reesei QM 9414. Sophorose could induce the synthesis of CMCase and ${\beta}-glucosidase$ simultaneously. Optimal induction medium by sophorose had the potassium citrate buffer solution of pH 3.0-4.0 for CMCase, but one of pH 5.0-6.0 for ${\beta}-glucosidase$. At this time, two different types of ${\beta}-glucosidase$ could be induced by sophorose: one was extracellular and had maximum at pH 5.0, the other was intracellular and had maximum activity at pH6.5. Induction study showed that $methyl-{\beta}-glucoside$ was not a true inducer of ${\beta}-glucosidase$ and that large ${\beta}-glucosidase$ induction could be obtained only by the addition of sophorose into the induction medium. Glucose repressed the induction of cellulase by sophorose. The repression of glucose could not be overcome by the addition of cyclic AMP into the induction medium.

• Microbiology and Biotechnology Letters
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• 제16권6호
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• pp.499-504
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• 1988

Among the new yeast strains which were isolated from soils by incubating in the xylan containing minimal medium at 3$0^{\circ}C$, one strain(XB-33) was finally selected by the results of extracellular xylanase production test. The characteristics of XB-33 was almost consistent with those of the Cryptococcus ater. The formation of xylanase activity was induced by xylan and repressed by xylose or glucose. The xylanase was partially purified from the culture supernatant with DEAE-Sephadex A5O chromatography. The enzyme had a pH optimum for activity at 5.0 and its stability range was pH 5-7. The temperature optimum was at 5$0^{\circ}C$, but the enzyme activity was greatly lost by heating at 7$0^{\circ}C$ for 60 minutes. The hydrolysis products from xylan by crude enzyme detected by TLC, were xylose and n series of higher oligosaccharides. The Km value of xylanase was 20 (mg/ml).

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.2081-2084
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• 2007

A 2.5 kb aga gene encoding ${\alpha}$-galactosidase (${\alpha}$-Gal) from Leuconostoc mesenteroides SY1 was cloned into pSJE, an E. coli-Leuconostoc shuttle vector. The recombinant plasmid, pSJEaga, was introduced into Leuconostoc citreum KCTC3526 (ATCC49370) by electroporation. Transcription level of aga was the highest in cells grown on raffinose (1%, w/v) followed by cells grown on galactose, melibiose, fructose, glucose, and sucrose. Western blot using antibodies against ${\alpha}$-Gal showed similar results to slot-blot results and enzyme activity measurements. All the results indicated that the aga was successfully expressed in L. citreum and its transcription was under the carbon catabolite repression (CCR).

• BMB Reports
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• 제45권8호
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• pp.458-463
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• 2012

We investigated the mechanisms involved in KHG26377 regulation of glutamate dehydrogenase (GDH) activity, focusing on the roles of SIRT4 and SIRT3. Intraperitoneal injection of mice with KHG26377 reduced GDH activity with concomitant repression of glucose-induced insulin secretion. Consistent with their known functions, SIRT4 ribosylated GDH and reduced its activity, and SIRT3 deacetylated GDH, increasing its activity. However, KHG26377 did not affect SIRT4-mediated ADP-ribosylation/inhibition or SIRT3-mediated deacetylation/activation of GDH. KHG26377 had no effect on SIRT4 protein levels, and did not alter total GDH, acetylated GDH, or SIRT3 protein levels in pancreatic mitochondrial lysates. These results suggest that the mechanism by which KHG26377 inhibits GDH activity and insulin secretion does not involve ADP-ribosylation of GDH by SIRT4 or deacetylation of GDH by SIRT3.

• Journal of Microbiology and Biotechnology
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• 제6권6호
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• pp.425-431
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• 1996

The enzymatic characteristics of Alcaligenes latus were investigated by measuring the variations of various enzyme activities related to biosynthesis and degradation of poly-${\beta}$-hydroxybutyrate (PHB) during cultivation. All PHB biosynthetic enzymes, ${\beta}$-ketothiolase, acetoacetyl-CoA reductase, and PHB synthase, were activated gradually at the PHB accumulation stage, and the PHB synthase showed the highest value among three enzymes. This indicates that the rate of PHB biosynthesis is mainly controlled by either ${\beta}$-ketothiolase or acetoacetyl-CoA reductase rather than PHB synthase. The enzymatic activities related to the degradation of PHB were also measured, and the degradation of PHB was controlled by the activity of PHB depolymerase. The effect of supplements of metabolic regulators, citrate and tyrosine, was also investigated, and the activity of glucose-6-phosphate dehydrogenase was increased by metabolic regulators, especially by tyrosine. The activities of ${\beta}$-ketothiolase and acetoacetyl-CoA reductase were also activated by citrate and tyrosine, while the activity of PHB depolymerase was depressed. The increased rate and yield of PHB biosynthesis by metabolic regulators may be due to the increment of acetyl-CoA concentration either by the repression of the TCA cycle by citrate through product inhibition or by the activation of sucrose metabolism by the supplemented tyrosine.

• Korean Journal of Microbiology
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• 제30권3호
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• pp.199-206
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• 1992

Six isolated strains degrading aniline were selected, identified and designated as pseudomonas putida K6, Pseudomonas acidovorans K82, Achromobacter gr. D. V. K24, Achromobacter xylosocidans K4, Moraxella sp. K21 and Moraxella sp. K22. All of them degraded 1000 ppm aniline completely within 30 to 36 hours. Most of these strains are resistant to antibiotics more than one, but Moraxella sp. has not any antibiotic marker tested. Most strains except for P. acidovorans K82 were shown to have resistance to the heavy metal ions such as Ni, Cu, Li, Ba, Co, etc. but not to Hg to which only P. putida K6 was resistant. M. sp. K21 was capable of degrading aniline to a maximum concentration of 2500 ppm without any repression. The incubation of the cell in limited pH ranges (4-8) had no great effect on aniline degradation. The addition of bactopeptone to the minimal media promoted the speed of aniline degradation, but the addition of glucose rather repressed the rate of aniline degradation. Through enzyme assay, A. gr. D. V. K 24 was shown to degrade aniline through artho-pathway and formed .betha.-ketoadipate as intermediate metabolite.

• Journal of Life Science
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• 제8권4호
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• pp.387-394
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• 1998

A thermophilic bacterium (strain DG0303) producing a thermostable $\alpha$-glucosidase was isolated from manure and identified as Bacillus sp. Strain DG0303 produced high level of $\alpha$-glucosidase compared with other thermophilic Bacillus strains. The cellular protein patterns were also compared with other Bacillus strains by sodium dodecyl sulfatepolyacrylamide gel electrophoresis(SDS-PAGE). On the basis of 16S rDNA analysis the Bacillus sp. DG0303 was found to be a member of Bacillus rDNA group 5. The optimum temperature for growth was 65$\circ$C and no growth was obtained at 40$\circ$C or 75$\circ$C. The optimum pH for growth was 5.5 to 8.5. $\alpha$-glucosidase activity was produced during growth and most activity was detected in the culture supernatant. The $\alpha$-glucosidase production was constitutive in the absence of carbohydrates. High level of enzyme activity was detected when the culture was grown on medium containing starch. Addition of glucose resulted in the repression of the $\alpha$-glucosidase production. The optimum pH and tempoerature for enzyme activity were pH 5.0 and 65$\circ$C, respectively. When analyzed by zymogram, the culture supernatant showed a single $\alpha$-glucosidase band with a molecular weight of approximately 60,000.

• Journal of Microbiology and Biotechnology
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• 제3권1호
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• pp.1-5
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• 1993

The gene for mannose enzyme II of phosphoenolpyruvate-dependent phosphotransferase system from Corynebacterium glutamicum KCTC 1445 was cloned into Escherichia coli ZSC113 using plasmid pBR 322. The recombinant plasmid, designated pCTS3, contained 2.2 kb DNA fragment, and the physical map of the cloned DNA fragment was determined. The E. coli ptsM ptsG mutant transformed with pCTS3 restored glucose and mannose fermentation ability, and grew well on these sugars as the sole carbon source in the minimal medium. The transform ant harboring pCTS3 showed a PTS-mediated repression of growth on maltose by mannose analogue, 2-deoxyglucose. The specificity of the response to 2DG therefore indicates that the cloned DNA fragment carries mannose enzyme II gene.

• Microbiology and Biotechnology Letters
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• 제5권4호
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• pp.177-184
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• 1977

Arylsulfatase catalyzes the release of SO$\sub$4//sup2/- from sulfate esters of simple phenols. Arylsolfatase occurs widely in animal tissues and in microorganisms including soil bacteria. Its widespread distribution suggests that it has a rather fundamental function and environmental meaning. It has been shown previously that arylsulfatase of Klebsiella was purified and characterized. A condition of arylsulfatase synthesis was tested with several strains of Serratia. Serratia marcescens could not utilize some sugars, such as xylose, rhamnose, glucosamine and arabinose hut glucose and mannitol as a sole carbon source. However, arylsulfatase synthesis was repressed by glucose but not by mannitol. The enzyme synthesis was repressed ob inorganic sulfate and methionine, and this repression was relieved by addition of tyramine. Arylsulfatase of S. marcescen was purified by fractionation with ammonium sulfate and followed by chromatographies on DEAE-Cellulose CM-Cellulose, and DEAE-Sephadex A-25. The molecular weight of arylsulfatase was determined to be 46,000 by SDS-Gel electrophoresis and 49,000 by Sephadex G-100 column chromatography. The enzyme showed some different properties with that of K. aerogenes. The activity was maximum at pH 6.8. The Km and Vmax values for p-nitrophenyl sulfate were 2.5${\times}$10$\^$－4/ M and 20 nmoles/min/mg protein, respectively. The enzyme showed high activities toward phenyl sulfate, ο-and p-nitro phenyl sulfates, and p-nitrocatechol sulfate. The inhibition of enzyme was strongly affected by hydroxylamine, inorganic fluoride, sulfide and phosphate, but by inorganic sulfate. Like Klebsiella arylsulfatase, tyramine, octopamine, and dopamine gave signifcant inhibitory effect.