- Degradation of Malic Acid by Issatchenkia orientalis KMBL 5774, an Acidophilic Yeast Strain Isolated from Korean Grape Wine Pomace
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Sung-Hee Seo , Chang-Ho Rhee , Heui-Dong Park
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J. Microbiol. 2007;45(6):521-527.
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DOI: https://doi.org/2641 [pii]
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 Abstract
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Several yeast strains degrading malic acid as a sole carbon and energy source were isolated from Korean wine pomace after enrichment culture in the presence of malic acid. Among them, the strain designated as KMBL 5774 showed the highest malic acid degrading ability. It was identified as Issatchenkia orientalis based on its morphological and physiological characteristics as well as the nucleotide sequences of the internal transcribed spacer (ITS) I-5.8S rDNA-ITS II region. Phylogenetic analysis of the ITS I-5.8S rDNAITS II sequences showed that the KMBL 5774 is the closest to I. orientalis zhuan 192. Identity of the sequences of the KMBL 5774 was 99.5% with those of I. orientalis zhuan 192. The optimal pH of the media for the growth and malic acid degradation by the yeast was between 2.0 and 3.0, suggesting that the strain is an acidophile. Under the optimized conditions, the yeast could degrade 95.5% of the malic acid after 24 h of incubation at 30°C in YNB media containing 2% malic acid as a sole carbon and energy source.
- Degradation of Cholesterol by Bacillus subtilis SFF34 in Flatfish during Fermentation
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Kwan-Pil Kim , In-Koo Rhee , Heui-Dong Park
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J. Microbiol. 2003;41(4):284-288.
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Abstract
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Bacillus subtilis SFF34 degrading cholesterol was applied to reduce residual cholesterol content in fermented flatfish. When the bacterial cells were inoculated as a start culture, a maximal level (1.7 U/g)
of cholesterol oxidase was obtained after 10 days, which was two times higher than that (0.8 U/g) without inoculation. Residual cholesterol contents with and without inoculation of the cells were 0.5 mg/g and 0.8 mg/g after 12 days of fermentation, respectively. Cholesterol derivatives including cholesterol- 5?, 6?-epoxide, 4-cholesten-3-one and 7?-hydroxycholesterol were detected in raw flatfish as well as fermented flatfish. Campesterol and 25-hydroxycholesterol were detected only after fermentation. However, no significant differences in their contents were observed regardless of inoculation.
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