• Microbiology and Biotechnology Letters
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• v.29 no.2
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• pp.96-103
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• 2001

Phaffia rhodozyma is the most promising microbial source of astaxanthin production, though wild-type strains are needed to increase the astaxanthin content for commercial production. To increase astaxanthin content for commercial production, a mutant strain of P. rhodozyma was selected and culture conditions of the mutant selected were optimized. P. rhodozyma was treated with mutagenic agent such as NTG, acriflavine, and UV in serial order and carotenoids hyper-producing mutant strain was selected based on the capabilities of cell growth on the agar plate containing chemical inhibitors and carotenoids production. Among the mutants tested, a mutant WS-2 was finally selected. Mutant WS-2 produced 1.26mg carotenoids/g-dry cell weight and this value was about- 4-folds higher than that of wild-type. The optimum culture conditions were $24^{\circ}C$ of temperature, 1.5vvm of aeration and 300rpm of agitation. In the optimized condition, cell and carotenoids concentrations were 7.62g/l and 14.9mg/l, respectively.

• Korean Journal of Veterinary Research
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• v.36 no.2
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• pp.463-470
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• 1996

The red yeast Phaffia rhodozyma, which contains astaxanthin(3, 3'-dihydroxy-$\beta$, $\beta$-carotene-4, 4'-dione) as its primary carotenoid, was tested as a dietary pigment source for egg yolks of laying hens. When the yeast was fed to laying hens at several concentrations, the intensity of redness in egg yolks was dependent on the yeast concentration in the feed and the deposition period. Addition of P rhodozyma in feed did not cause any visible adverse effect on laying hens.

• Journal of Microbiology and Biotechnology
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• v.2 no.1
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• pp.46-49
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• 1992

The availability of Phaffia rhodozyma as an astaxanthin sources in the aquaculture industry is limited because of the low carotenoid content of natural isolate. In this study, we have used the protoplast fusion technique to construct cell hybrids with an increased content of astaxanthin from P. rhodozyma. Cell hybrids (F307 and F406) obtained were very stable and produced considerably more astaxanthin (> 1 mg/g yeast) than the wild parent. Karyogamy was confirmed by the isolation of recombinants after mitotic segregation of parental auxotrophic genetic markers, the increased amount of chromosomal DNA/cell and the presence of single nucleus/cell.

• The Korean Journal of Food And Nutrition
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• v.16 no.3
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• pp.165-170
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• 2003

A sensitive and accurate method for the detection of astaxanthin was developed. The optimum HPLC system for the extraction and quantification of astaxanthin was based on a reversed phase column, and a quaternate mobile phase contained dichloromethane. The amount of astaxanthin can be accurately quantified in Phaffia rhodozyma cultures. The results of this study suggest that the mixture solution of dimethylsulphoxide and acetone is the optimal extraction solvent for astaxanthin and samples treatment for astaxanthin analysis must control low temperature and absent light operation strictly.

• Journal of Microbiology and Biotechnology
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• v.5 no.6
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• pp.370-372
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• 1995

A Phaffia rhodozyma chromosomal fragment (approximately 3.8 kb) capable of functioning as an origin for the replication of a kanamycin resistance ($Km^r$) plasmid in S. cerevisiae was isolated by the use of origin search plasmid, pHN134. In S. cerevisiae, transformation frequencies using the plasmid pHN134 containing an autonomously replicating sequence of P. rhodozyma was 450-580 CFU/$\mu g$ DNA. The stability of the recombinant plasmid were 16-19$\%$.

• Food Science and Preservation
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• v.11 no.1
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• pp.126-129
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• 2004

To elucidate the effect of various natural antioxidants on the safflower oil, rosemary extract, green tea extract, isoflavon, Phaffia rhodozyma extract, tocopherol, sesamol, and BRA as a control were added to the safflower oil and stored at 60$^{\circ}C$ for 4 weeks. During storage, its viscosity and antioxidative activity were determined. Viscosity of the oil increased with increasing storage period and was related with its antioxidative acvtivity. Antioxidative avtivity among antioxidants used in this study were in order of green tea extract>BHA>tocopherol>rosemary extract>isoflavon>sesamol>Phaffia rhodozyma extract. Green tea extract was the best in terms of antioxidative acvtivity. After 4 weeks, its peroxide value decreased up to 80.4％ of the control, and 42.1％ for acid value and 47.4％ for TBA value decreased.

• Journal of Microbiology and Biotechnology
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• v.6 no.2
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• pp.103-109
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• 1996

Mn(II)+succinate decreased the carotenoid formation of the yeast Phaffia rhodozyma, probably by scavenging $O_2$. When duroquinone (DQ), an internal and external $O_2$ generator, was added to medium, P. rhodozyma produced more amount of carotenoids. The increased carotenoid production was destroyed by oxygen radical (OR) scavengers, ascorbate+Cu(II) and dimethylsulfoxide. When sub-lethal concentrations of $H_2O_2$ , an external OR source, and antimycin, an internal OR inducer, were used, the effect of $H_2O_2$ on carotenoid formation and composition was less significant than that of antimycin. Addition of superoxide dismutase, an external OR remover, rescued cells from death caused by the high concentration of DO. In this condition, the yeast culture showed an increase in carotenoid content. Addition of DQ into P. rhodozyma culture in the stationary phase did not increase carotenoid production. Therefore, carotenoid formation was stimulated by internal ORs in the growing yeast. It was probably due to release of catabolite repression on carotenogenesis in the yeast. Aeration was important for carotenoid production but was not as effective as the internal OR producer, DQ.

• Journal of Microbiology and Biotechnology
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• v.6 no.2
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• pp.110-115
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• 1996

Yellow mutants of the astaxanthin producing red yeast Phaffia rhodozyma were obtained by nitrosoguanidine mutagenesis. The carotenoid composition of the yelow mutants, Yan-1 and Ny-1, was mainly $\beta$ -carotene (> 95$%$) and torulene (< 5$$). Therefore, the yellow mutants are carotene oxygenation deficient mutants (CODMs). CODMs produced decreased quantities of carotenoids compared to their red parents and this indicated that carotene may regulate its synthesis. CODMs, Yan-1 and Ny-4, on plates containing 50 $\mu$ M antimycin, showed highly pigmented vertical papillae. Antimycin-induced mutants purified from the papillae showed increases in carotenoid content (up to 1 mg $\beta$-carotene/g yeast). CODMs, Yan-1 and Ay-1, were more sensitive to antimycin than red strains, Ant-1 and 67-385. This was probably due to lower antioxidant activity of $\beta$-carotene than that of astaxanthin. Light increased torulene and light+antimycin further increased the torulene. Yan-1 and Ny-4 could grow with succinate, though their red parents, Ant-1 and Anf-1p, could not. However, antimycin induced mutation of Yan-1 or Ny-4 destroyed the ability to grow with succinate.

• The Korean Journal of Mycology
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• v.21 no.1
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• pp.9-15
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• 1993

ABSTRACT: The cell fusants were constructed from complementary auxotrophic mutants of Phffia rhodozyma. The nuclear fusion of the fusants was demonstrated by several techniques including comparision of cell volume, estimation of DNA content and nuclear staining. The cell fusants were very stable for succeeding transfer culture on complex medium for more than one year. Malt extract (1%, w/v) and abscisic acid(1 mM) increased the carotenoid formation whereas gibberellic acid(5mM) and riboflavin(0.1 mM) decreased the corresponding content.

• Journal of Microbiology and Biotechnology
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• v.13 no.2
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• pp.175-181
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• 2003

The production of a carotenoid astaxanthin, a growth-associated principal pigment, is limited in a batch cultivation, because a high glucose concentration severely inhibits the cell growth and also influences the carotenoid production. Therefore, a fermentation strategy including effective chemicals for the high-level production of cells and astaxanthin by a mutant strain Phaffia rhodozyma AJ-6-1 was developed in a fed-batch culture. First, a production medium for maximizing the cell and astaxanthin yields was formulated and optimized. Using this optimized medium, the highest cell and astaxanthin concentrations obtained were about 38.25 g/1 and 34.77 mg/1, respectively. In addition, an attempt was made to increase the amount of astaxanthin using effective chemicals such as ethanol and acetic acid, which are known at an inducer and/or precursor of carotenoid synthesis. When either 10g/1 ethanol or 5 g/1 acetic acid was added to investigate the resulting astaxanthin content, a relatively high astaxanthin concentration or 45.62 mg/l and 43.87 mg/1, respectively, was obtained, and the cell concentrations also increased slightly under these conditions. Therefore, these results imply that a fed-batch culture of the mutant strain P. rhodozyma AJ-6-1 could be effectively employed in the commercial production of astaxanthin, although the factors affecting the productivity remain to be elucidated.