亚硝酸还原酶高产菌株的筛选及发酵条件优化

通过紫外线对巨大芽孢杆菌MPF-906进行了诱变处理，提高了产酶能力，变异株Z85酶活达到28.76 U/mL。进一步对其发酵条件进行研究，优化了培养基和培养条件。优化的培养基为：葡萄糖1.5%，牛肉膏0.2%，硫酸铵0.1%，K₂HPO₄ 0.135%，KH₂PO₄ 0.07%，NaCl 0.1%；无机盐溶液10 mL/L（即MgSO₄·7H₂O 0.04%、MnSO₄·H₂O 0.001%、CaCl₂·2H₂O 0.002%）。发酵条件为：摇床转速160 rpm，接种量4%，初始pH 6.5，30 ℃发酵20 h。在此最优化条件下，亚硝酸还原酶的酶活达到45.94 U/mL。

Screening of High Nitrite Reductase Producing Strains and the Optimization of Fermentation

The nitrite reductase production strain B.megaterium MPF-906 was treated with UV. The high nitrite reductase producing mutant Z85 was obtained and its nitrite reductase activity was 28.76 U/mL. The effects of compositions of culture medium and cultural conditions on nitrite reductase production were investigated. The optimal culture media are: glucose 1.5%, beef extract 0.2%, (NH4)2SO4 0.1%, K2HPO4 0.135%, KH2PO4 0.07%, NaCl 0.1%, MgSO4 · 7H2O 0.04%, MnSO4 · H2O 0.001%, CaCl2 · 2H2O 0.002%. The fermentation conditions are 30℃ for 20 h, 160 rpm, initial pH 6.5 and 4% of inoculation. Under this optimized conditions, the nitrite reductase activity reached 45.94 U/mL.