产β-甘露聚糖酶内生菌的诱变育种及产酶条件优化

Mutation Breeding of a β-Mannanase-producing Endophytic Bacteria and Optimization of its Fermentable Condition

以刺槐豆内生菌Paenibacillus sp.CH-3为出发菌株,采用紫外-硫酸二乙酯-亚硝酸盐对其进行复合诱变,并对菌株的发酵条件进行了优化。结果表明:经过紫外线-硫酸二乙酯-亚硝酸盐复合诱变,获得一株高产β-甘露聚糖酶的突变菌株Paenibacillus sp.CH3-05,其酶活力为160.2U/mL,较出发菌株(42U/mL)提高了281.4%。其最佳发酵培养基为:酵母膏0.25%,魔芋粉3%,磷酸氢二铵0.25%,氯化钠0.1%,硫酸镁0.3%,磷酸氢二钾0.2%,CaCl22 mmol/L。最佳发酵条件为:初始pH 6.5,接种量2%,培养温度35℃,转速200 r/min,培养时间78 h,在该条件下测得酶活为233.5 U/mL,较出发菌株提高456%。

The mutagenic effects of ultraviolet-diethyl sulfate-nitrite for compound mutagenesis on the original strain Paenibacillus sp. CH-3（42 U/mL） screened from locust bean were studied. Furthermore, the fermentation conditions of strain were optimized. Results of compound mutagenesis showed that a mutant strain（160.2 U/mL）with a high-yield β-mannanase production, named Paenibacillus sp. CH3-05, was obtained after the ultraviolet-diethyl sulfate-nitrite compound mutagenesis. The activity of mutant strain increased 281.4% compared with that of the original strain Paenibacillus sp. CH-3. The optimal medium for β-mannanase production were determined as follows： Yeast extract 0.25%, konjaku flour 3%,（NH4）2HPO40.25%, NaCl 0.1%, MgSO40.3%, K2HPO40.2%,CaCl22 mmol/L. The best fermentation condition was as following： Initial pH value 6.5, inoculum size 2%, culture temperature 35℃, rotate speed 200 r/min, culture time 78 h. Under these circumstances, the highest enzyme activity was 233.5 U/mL. The activity of mutant strain increased 456% in comparison with that original strain.