• KSBB Journal
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• v.15 no.2
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• pp.125-133
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• 2000

Specific carotenoids and astaxanthin biosynthesis power of Phaffia rhodozyma mutant 876, which was obtained after NTG a and UV treatments, was higher than those of the wild type by 40% and 50%, respectively. The mutant strain did not show t the catabolite repression even at 22% (w/v) glucose concentration. The optimum C{N ratio was 2.0, and the optimum t temperature and initial pH were $22^{\circ}C$ and 6.0, respectively. 80th cell growth and astaxanthin formation decreased drastically a as the fermentation temperature was increased over $22^{\circ}C$, whereas they were comparable in the pH range between 5.0 and 7 7.0. Inoculum size did not affect the final cell density nor the carotenoids biosynthesis, and 3%(v/v) was selected as optimal. H Higher dissolved oxygen concentration facilitated astaxanthin biosynthesis, and aeration rate of 1.0 v/0/m and agitation speed of 400 rpm were selected as optimum. The final cell dens때 of 43.3 g/L and the volumetric astaxanthin and carotenoids concentrations of 110.6 mg/L and 149.4 mg/L, respectively, were obtained. The specific carotenoids concentration was 3.45 m mg{g-yeast(dry). Yx/s and Yp/s values of 0.37 and 1.08 were obtained. The result of this study will provide basic information u useful for mass production of astaxanthin from P. rhodozyma fermentation.

• Microbiology and Biotechnology Letters
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• v.8 no.3
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• pp.173-180
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• 1980

A source of D-xylose was required for the enhanced production of D-glucose isomerase of Streptomyces sp. strain K-17. D-glucose supported the luxuriant growth of the organism as well as D-xylose, but D-glucose isomerase activity was hardly detected in the D-glucose-grown cells. When the D-glucose-grown cells were incubated aerobically for a few hours in 0.5% xylose solution in 0.05 M phosphate buffer, pH 7.0, it was found that inductive formation of D-glucose isomerase occurred in the cells without multiplication. In the non-growth phase of cells the inductive formation of D-glucose isomerase occurred because a source of nitrogen for the synthesis of enzymes was obtained from turnover of protein accumulated in cells. D-ribose, L-arabinose, D-glucose, D-mannose, citrate, succinate and tartrate could not induce the formation of D-glucose isomerase, but D-xylose could induce. Inductinn of D-glucose isomerase was repressed by D-glucose and its catabolites : glycerol, succinate and citrate. Inductive formation of the enzymes in the non-growth phase was stimulated by $Ba^{2+}$, $Mg^{2+}$ and $Co^{2+}$, and inhibited by C $u^{2+}$, C $d^{2+}$, A $g^{+}$and H $g^{2+}$. The synthesis of enzymes in the induction system composed of 0.5% xylose solution was disrupted by actinomycin D, streptomycin, chloramphenicol, kanamycin, tetracycline, p-chloromercuribenzo ate, arsenate and 2, 4-dinitrophenol, but not disrupted by mitomycin C and penicillin G.icillin G.

• 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.

• 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.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.443-448
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• 1996

In order to investigate the function of xylA promoter(Pxyl) as regulatory region Pxyl-lacZ fusion gene was constructed by the insertion of xylA promoter to the multiple cloning site of upstream of lacZ gene in a multicopy numbered plasmid pMC1403 containing promoterless lac operon, which was designated pMCX191, and Pxyl-lacZ fragment from pMCX191 was inserted to low copy numbered plasmid pLG339, designated pLGX191. The expressions of ${\beta}-galactosidase$ in these recombinant plasmids containing Pxyl-lacZ fusion gene were induced strongly by the addition of xylose, repressed by the addition of 0.2% glucose in the presence of xylose. The catabolite repressions were derepressed by the addition of 1 mM cAMP as same as native xylA gene. The fragment of xylA promoter was partially deleted from the upstream of xylA promoter by exonuclease III to investigate the regulation site of xylA promoter and the degrees of deletion derivatives of xylA promoter were analyzed by the DNA base sequencing. By the investigations of the induction by xylose, repression by glucose and derepression by cAMP on xylose isomerase production, the regulation site of xylA promoter may be located in segment between -165 and -59 bp upstream from the initiation site of xylA translation.