极地适冷菌Pseudoalteromonas sp. QI-1产适冷蛋白酶发酵条件的优化

对极地适冷菌Pseudoalteromonas sp. QI-1产适冷蛋白酶的发酵条件进行优化。结果表明:菌株QI-1的最适生长和产酶温度均为5℃;最佳接种量为1%;发酵培养基的最适初始pH和最佳装样量分别为5和10%;盐度为2%时对菌株的生长和产酶最为有利;麸皮和醋酸钠分别为最佳N源和C源;添加0.75%酪蛋白时菌株QI-1胞外蛋白酶的活性最高;10 mmol/L Mg2+和0.5%Tween-80有利于产酶。正交试验结果表明:菌株Pseudoalteromonassp. QI-1产蛋白酶较佳培养基配方(g/L)为麸皮5,酵母粉2.5,酪蛋白3,MgCl2.6H2O 3,KCl 1.5;发酵液比酶活为166.20 U/mL,较优化前提高了约56%。

Optimization of cold-active protease production by polar psychrotrophic bacterium Pseudoalteromonas sp.QI-1

The culture conditions of polar psychrotrophic bacterium Pseudoalteromonas sp.QI-1 were optimized for the production of cold-active protease.The optimum fermentation conditions were determined as follows：optimal temperatures for growth and enzyme production were both at 5 ℃,inoculation volume was 1%,and liquid volume was 10% at pH 5.Culture medium for protease production of strain QI-1 was also studied.Results showed that nitrogen source and carbon source preferred by protease production were bran and sodium acetate.2% NaCl,10 mmol/L Mg2＋,0.5% Tween-80 and 0.75% casein were suitable for the enzyme production.The orthogonal experiment design showed that the optimum medium（per liter） consisted of 5 g bran,2.5 g yeast extract,3 g casein,3 g MgCl2·6H2O and 1.5 g KCl.Under the optimum condition,the protease activity was up to 166.20 U/mL and the yield of protease increased about 56%.