Abstract:The strain N-6，which produces high levels of nitrite reductase，was screened from pickles.It was identified as Lactobacillus rhamnosus by 16SrDNA sequencing.Nutrient composition （using different carbon，nitrogen，and phosphorus sources），cultivation method，cultivation temperature，and other conditions were optimized.The optimal medium for L.rhamnosus N-6 was as follows：2% glucose，0.5% casein peptone，0.2% dipotassium hydrogen phosphate，aerobic culture at 37℃.Purification of nitrite reductase by ammonium sulfate gradient precipitations，dialysis，diethylaminoethylcellulose anion exchange chromatography，yielded an increase in enzyme activity from 60.83 U/mL to 764.49 U/mL，effectively improving the purity of nitrite reductase.