产乳糖酶酵母Kfragilis株增殖培养发酵条件的优化

A Further Study on Lactase-Producing yeast K fragilis:the Selection of Optimal Medium and Condition for the Production of yeast cells

目的：提高发酵液单位体积的酵母细胞总量，以提高酶得率。方法：采用单因素试验方法，对影响酵母生长的主要限制因子──培养液中可利用的糖含量进行了试验。用细胞浊度法来表示酵母细胞的增殖情况，Nelson－Somogyi法测定培养液中可利用的糖含量，凯氏定氮法测培养液中的氮含量，PH计测定PH值。结果：确定了Kfragilis酵母株增殖培养的较佳配方，当选择原色砂糖浓度为10％、pH为6时，细胞量比原配方提高了3．65倍。单位酶产量达122．4IU／ml。结论：优化后的该菌株增殖培养条件下，该菌株生长产酶情况良好，可用于生产。

objective To increase the concentration of the yeast cells in the fermentation culture and increase the enzyme productivity. Methods:The key effect factor-the usable sugar content in the incubation sus-pension was analysed by the method of monofactor analysis. Cell turbidity at 680 urn was used to indicate theproduction of yeast cells. The usable sugar content in the incubation suspension was determined by Nelson-Somo-gyi method. Nitrogen content was measured by Kjeldahl determination method and PH measured by PH meter.Results:The optimum reproduction medium was determined. The final yeast cell production increased more thanthree folds when the strain was cultivated in medium as compared to the conventional medium compostion,and ahigh enzyme productivity(122. 4 IU/incubation suspension) was obtained. Conclusion: A further study on yeastcell production was completed. The result of this experiment showed that this strain would be good for industrialproduction.