| The effects of UVB on the growth of yeast, physiological properties and substances were studied. The optimum hydrolysis condition of yeast cells cultured by UVB was determined, and the application of Live Yeast Cell Derivative (LYCD) in cosmetic was studied.1. UVB radiation had the effects on the growth of yeast. It was apparent when the inoculation was less than 1×10~7/mL, but the effects were not significant different if the inoculation was raised. The death rate of yeast was decreased when the medium was made with pH5.0 citric acid-natrium citrate buffer solution. Yeast cell agglutinated with the prolonged time of the UVB culture, which proved that the structure of cell wall was changed in the UVB culture.2. The results showed that the contents of RNA, protein, trehalose, ergosterol and glucan in yeast cells increased to a certain extent. But the contents of GSH and the activity of SOD decreased. UV-B influenced greatly the growth of yeast, and different changes of many kinds of physiological substances contents had appeared.3. The optimum hydrolysis condition of yeast cells cultured by UVB was determined with orthogonal test after the factors that influenced the hydrolysis were studied respectively. The optimum processes condition was that the suspension of yeast cell 12%, neutrase 3% (dry weight of the cells), pH6.0, 50 ℃ and the time of hydrolysis 28h. The effects of hydrolysis could be improved by adding cellulase 1%.4. The components of LYCD were analyzed. A little molecule glycopeptide with O-glucopeptide bond was found.5. The electric conductivity of skin smeared with moisturizing frost adding LYCD increased from 10-20% according the control, which proved that the moisturizer effects of skin cream increased after adding LYCD. |
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