• Food Science and Preservation
• /
• v.8 no.1
• /
• pp.92-101
• /
• 2001

In order to develop the Production and application of cholesterol oxidase, a cholesterol degradation bacteria which produces a remarkable amount of extracellular cholesterol oxidase has been isolated from Korea traditional salt fermented flat fish. The isolated strain was identified as a strain of Bacil1us sp. based on its morphological, physiological characteristics and cellular fatty acid compositions. Experiments were carried out to optimize the condition of cholesterol oxidase production using Bacillus sp. SFF34. Bacillus sp. SFF34 was shown to give the maximum yield of cholesterol oxidase in the medium containing 2.0% glucose, 0.5% yeast extract, 0.02% MgSO$_4$$.$7H$_2$O, 0.025% K$_2$HPO$_4$, 0.15% NH$_4$NO$_3$ and 0.2% cholesterol. The optimum culture conditions, temperature, initial pH and agitation speed were 30$^{\circ}C$, 7.0 and 150rpm respectively. The enzyme production reached a maximum level at 24 hrs of cultivation(2.42 U/ml).

• KSBB Journal
• /
• v.13 no.4
• /
• pp.343-351
• /
• 1998

About 75 strains which utilize cholesterol as sole carbon and energy source were isolated from 10 samples of Kimchi and 18 samples of fermented fish food (2 Ojingo-jeots, salt-fermented squid ; 5 Changran-jeots, salt-fermented pollack tripe ; 5 Myungran-jeots, salt-fermented Alaska pollack roe ; 3 Gajami-sikhae-jeots, fermented flat fish ; 2 Gul-jeots, salt-fermented oyster ; a Juneo-jeots, salt-fermented shad). Among them tested, the 3T6-5Mj strain isolated from Changran-jeot showed the highest activity on cholesterol degradation. The optimal composition of medium for the producing cholesterol degradation enzyme by 3T6-5Mj strain was 1.0 g/L NH4NO3, 1.0 g/L K2HPO4, 0.1 g/L MgSO4.7H2O, 1.0 g/L FeSO4.7H2O, 1 g/L NaCl, 5 g/L Trypton, 1 g/L Cholesterol, and 5 g/L Maltose at 30$^{\circ}C$, pH 7.5, and the enzyme production reached a maximum level at 140 hours of cultivation.

• Microbiology and Biotechnology Letters
• /
• v.11 no.1
• /
• pp.53-58
• /
• 1983

Sik-hae is a traditional Korean fermented fish product which is made from flat-fish, garlic, salt, red pepper and millet. The changes in chemical composition, pH, acidity and the contents of Amino-N, VBN, TMA and organic acids were investigated during the fermentation of Sik-hae. The changes in the microflora, enzyme activity and the sensory quality including textural characteristics were also evaluated. The changes in the contents of crude protein, crude fat and moisture during Sik-hae fermentation were negligible. The pH of the product tended to decrease in the course of fermentation and it showed the minimum value of 4.5 after 7 days of fermentation. On the other hand the acidity continued to increase up to 2300mg % by 4 weeks of fermentation. Lactic acid was the major organic acid. The content of Amino-N in sik-hae gradually increased up to 673.6mg % by 2 weeks of fermentation, and then slightly decreased. The content of VBN increased rapidly during the first 2 weeks of fermentation, while little changes in TMA content was observed. The number of proteolytic bacteria increased slightly for the first 2 weeks and then rapidly decreased. The number of yeast and acid forming bacteria increased rapidly from the 4th day to the 14th day of fermentation and then decreased. Both lipase and protease activities showed the maximum at the 11th day of fermentation. The texture softening of the fish occurred after 1 week of fermentation and the adhesiveness appeared after 2 weeks of fermentation. Summarizing these results, the optimum fermentation time for Sik-hae from flat fish were 2 weeks at 2$0^{\circ}C$ and the quality of the product could be kept for up to 4 weeks in refrigerator.