嗜热芽孢杆菌β-半乳糖苷酶发酵条件研究

Study on Fermentation Condition of β-galactosidase by Bacillus sp.

以嗜热芽孢杆菌为菌种，研究发酵生产β－半乳糖苷酶的条件。应用均匀设计法优化发酵培养基组成，结果为（ｇ／Ｌ）：乳糖０．５、蛋白胨２．０、牛肉浸膏２．０、Ｋ２ＨＰＯ４ ０．０１。在温度５５℃、初始ｐＨ７．０、摇床转速２００ｒ／ｍ ｉｎ 和１０％ 接种量条件下，发酵２４ｈ，β－半乳糖苷酶酶活力达１３．２Ｕ／ｍ Ｌ。在乳糖水解反应中，证实该酶能催化转半乳糖苷反应，合成半乳糖低聚糖。

Bacillus sp. was used in producing β galactosidase. The fermentation medium was optimized by uniform design. The optimal medium was composed (g/L) of 0.5 lactose, 2.0 peptone, 2.0 beef extract and 0.01 K 2HPO 4. When the strain grew in the medium under condition of 55℃, initial pH 7.0, shaker speed 200r/min as well as 10% spore suspension inoculum for 24h, the enzyme activity in brothe was as high as 13.2 U/mL. The β galactosidase was able to synthesize galacto oligosaccharides owing to transgalatosyaltion during lactose hydrolysis.