• Journal of Microbiology and Biotechnology
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• v.17 no.12
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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).

• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1898-1903
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• 2007

We attempted to modulate the overall protein expression rate through the addition of a repressor against the araBAD promoter system of Escherichia coli, in which glucose was used as a repressor. Therefore, 0.5% L-arabinose was initially contained as an inducer in culture medium, and either 2% glucose or 2% glycerol was used as a carbon source, and it was found that the expression of recombinant interferon-${\alpha}$ could be observed at the beginning of the batch culture when glycerol was used as a carbon source. However, when glucose was used, the initiation of recombinant interferon-${\alpha}$ expression was delayed compared with that when glycerol was used. Furthermore, when the addition of 0.5% glucose was carried out once or twice after 0.5% L-arabinose induction during DO-stat fed-batch culture, the distributions of soluble and insoluble recombinant interferon-${\alpha}$ were modulated. When glucose was not added after the induction of L-arabinose, all of the expressed recombinant interferon-${\alpha}$ formed an inclusion body during the later half of culturing. However, when glucose was added after induction, the expressed recombinant interferon-${\alpha}$ did not all form an inclusion body, and about half of the total recombinant interferon-${\alpha}$ was expressed in a soluble form. It was deduced that the addition of glucose after the induction of L-arabinose might lower the cAMP level, and thus, CAP (catabolite activator protein) might not be activated. The transcription rate of recombinant interferon-${\alpha}$ in the araBAD promoter system might be delayed by the partial repression. This inhibition of the transcription rate probably resulted in more soluble interferon-${\alpha}$ expression caused by the reduction of the protein synthesis rate.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.461-467
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• 1989

The regulation of the synthesis of alcohol-oxidase (E.C.1.1.3.13.) was investigated in the methanol-utilizing yeasts during growth on different carbon sources. For this experiment, Hansenula polymoypha CBS 4132, Hansenula polymoypha CBM 11 and Hansenula polymoypha Cooney were cultured in mineral salt medium by changing its carbon sources. The production of alcohol-oxidase was varied by the carbon sources. For exmaple, alcohol-oxidase was undetectable: in all strains submitted to the test in the medium with glucose, but its production was rapidly increased when the carbon source was changed from glucose to methanol after 30 hrs of incubation. Moreover, this enzyme was not synthesized during growth on the primary aliphatic alcohols alone (ethanol, propanol, butanol or pentanol) or on the mixed substrates (0.5% methanol + 0.5% primary aliphatic alcohols). When cells were grown on the various carbon sources (glucose, xylose, lactose, glycerol, galactose, saccharose, sorbose, lactic acid or acetic acid), the alcohol-oxidase was about one-tenth of the activity found in cells grown on methanol alone. These carbon sources together with methanol yielded far better synthesis of alcohol-oxidase than in case of carbon sources alone. Especially, the alcohol-oxidase activity of the cells grown on lactose or lactic acid together with methanol was far better or similar than that of cells grown on methanol alone. The synthetic activity of alcohol-oxidase of Hansenula polymoypha CBS 4132 was the strongest among the three strains tested in every respect.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.243-249
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• 2017

An agar-degrading bacterium, designated as the GNUM08123 strain, was isolated from samples of red algae collected from the Yongil Bay near East Sea, Korea. The isolated GNUM08123 strain was gram-negative, aerobic, motile, and beige-pigmented, with $C_{16:0}$ (25.9%) and summed feature 3 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}2-OH$, 34.4%) as its major cellular fatty acids. A similarity search based on the 16S rRNA gene sequence revealed that it belonged to class Gammaproteobacteria and shared 97.7% similarity with the type strain Vibrio chagasii $R-3712^T$. The DNA G+C content of strain $GNUM08123^T$ was 46.9 mol%. The major isoprenoid quinone was ubiquinone-8. The results of DNA-DNA relatedness and 16S rRNA sequence similarity analyses, in addition to its phenotypic and chemotaxonomic characteristics, suggest that strain GNUM08123 is a novel species within genus Vibrio, designated as Vibrio sp. GNUM08123. Agarase production by strain GNUM08123 was induced by agar and sucrose, but was repressed probably owing to carbon catabolite repression by glucose and maltose.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.8-16
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• 2013

An agar-hydrolyzing marine bacterium, strain GNUM08120, was isolated from Sargassum fulvellum collected from Yeongil bay of East Sea of Korea. The isolate was Gram-negative, aerobic, motile with single polar flagellum, and grew at 1-10% NaCl, pH 5.0-8.0, and $15-37^{\circ}C$. G+C content and the predominant respiratory quinone were 46.13 mol% and Q-8, respectively. The major cellular fatty acids were Summed feature 3 (24.5%), $C_{16:0}$ (21.7%), and $C_{18:1}{\omega}7c$ (12.5%). Based on 16S rRNA gene sequence similarity and DNA-DNA hybridization analyses, strain GNUM08120 was identified as a novel subspecies of Alteromonas macleodii, designated Alteromonas macleodii subsp. GNUM08120. Production of agarase by strain GNUM08120 was likely repressed by the effect of carbon catabolite repression caused by glucose. The crude agarase prepared from 12-h culture broth of strain GNUM08120 exhibited an optimum pH and temperature for agarase activity at 7.0 and $40^{\circ}C$, respectively. The crude enzyme produced (neo)agarobiose, (neo)agarotetraose, and (neo)agarohexaose as the hydrolyzed product of agarose.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.327-333
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• 1991

This study was carried out to determine the effects of media compositions on cell growth and casein hydrolysis for cell production in order to add Micrococcus sp. LL3 as a potential agent for industrial application for the shortening of ripening period. Monosaccharides like glucose, mannose and fructose were mare excellent as carbon source, but arabinose and xylose markedly inhibited cell growth and caseinolysis. Among the organic nutrients, yeast extract was more effective for cell growth and for caseolysis. However, inorganic nitrogen sources were less effective than organic sources. Urea inhibited cell growth severely. Cell growth and caseinolysis were rather increased a little in the broth containing 1% NaCl, and the organism tolerated and grew in relatively high concentrations of NaCl up to 9%. Addition of vitamin did not affect cell growth and caseolysis in level of $0.1\;{\mu}g/ml$ concentration. Cell growth and caseinolysis were stimulated by addition of glutamic acid and $MgSO_4$ with concentration of 0.2% and 0.05% respectively.

• Journal of Life Science
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• v.7 no.1
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• pp.30-38
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• 1997

For screening thermostable $\alpha$-amylase from thermophiles, various samples from extreme environments such as hot spring and sewage near them, and compoat, wereexamined microbial growth in enrichment culture medium at 55$\circ$C on the assumption that enzymes from thermophiles are inevitable thermostable. One strain showing higher $\alpha$-amylase activity was pure cultured and designated as Bacillus sp. TR-25 from the results of morphological, cultural and physiological characteristics. The most important carbon sourses for the enzyme production were soluble starch, dextrin, potato starch and corn starch. Glucose and fructose had a catabolite repression on the enzyme production. The good nitrogen sources for the enzyme production were yeat extract, nutrient broth, tryptone, corn steep liquor and ammonium sulfate. The enzyme production was accelerated by addition of CaCl$_{2}$. $\cdot $ H$_{2}$O. The optimal medium composition for the enzyme production was soluble starch 2.0%, yeast extract 0.55, CaCl$_{2}$ $\cdot $ 2H$_{2}$O 0.015, Tween 80 0.001%, pH8.0, respectively. In jar fermenter culture, this strain shows a rapid growth and required cheaper carbon and nitrogen source. These properties are very useful to fermentation industry. The $\alpha$-amylase of this strain demonstrated a maximum activity at 80$\circ$C, pH 5.0, respectively. And calcium ion did not improve thermostability of the enzyme. At 10$0^{\circ}C$, this enzyme has 235 of relative activity. Transformation was carried out by thermophilic Bacillus sp. TR-25 genomic DNA. As a result, the transformant has increased thermostable $\alpha$-amylase activity.