酸性植酸酶产生菌的筛选、鉴定及发酵条件研究

Screening and Identification of a Strain Capable of Producing Acid Phytase and Optimization of Its Fermentation Conditions

从土壤中筛选到一株产酸性植酸酶酶活较高的菌株,初步鉴定为黑曲霉,菌株最优发酵条件为:麸皮3g/100mL、(NH4)2SO4 0.5g/100mL、发酵液初始pH5.5、发酵时间84h,酶活力可达12.06U/mL。对其粗酶液的酶学性质研究表明:该酶最适作用pH值为5左右,最适温度是45℃;该酶在55℃保温30min后酶活力保留在60%左右;在酸性和中性条件下有一定的稳定性;金属离子Ca2+、Fe2+、Na+、K+、Zn2+、Cu2+对酶有一定的抑制作用,Mg2+、Ba2+对酶有一定的激活作用。

A strain with higher acid phytase activity isolated from soil was identified as Aspergillus niger.The optimal fermentation conditions for improved production of phytase by the strain were incubation in a medium composed of 3 g/100mL wheat bran and 0.5 g/100mL（NH4）2SO4,at an initial pH of 5.5 for 84 h.Under the optimal fermentation conditions,the phytase activity was up to 12.06 U/mL.The optimal reaction pH and temperature of this enzyme were 5 and 45 ℃,respectively.The relative enzyme activity remained to be 60% after heating treatment at 55 ℃ for 30 min.In addition,the enzyme was stable in acidic and neutral media.The phytase activity was inhibited by Ca2＋,Fe2＋,Na＋,K＋,Zn2＋ and Cu2＋,while activated by Mg2＋ and Ba2＋.