中文摘要：

从豆瓣酱中筛选出一株能高效降解亚硝酸盐的菌株u01，经鉴定为蜡样芽孢杆菌．通过测定LJ01细胞中不同组分的酶活，研究了亚硝酸盐还原酶的初步定位．LJ01经100mg／L的NaN02诱导后，用溶菌酶破壁，粗酶液先经阴离子DEAESepharoseFastFlow层析柱分离，测定不同蛋白组分a、b、C降解亚硝酸盐的活力，利用0．1mol／L无机电子供体丁二酸和亚硫酸钠等鉴定出组分C为亚硝酸盐还原酶，再经葡聚糖凝胶G-150层析柱分离，获得较纯的亚硝酸盐还原酶，每升发酵液可得到O．54mg活性酶蛋白，酶蛋白活力达到4004．89U／mg，得率为2．37％，纯化后其NiR的比活力提高了17．57倍．经SDS—PAGE电泳后确定LJ01中亚硝酸盐还原酶的单体分子质量约为30ku．

英文摘要：

A strain LJ01 with strong nitrite degradation ability was isolated from fermented bean paste and was iden- tified as Bacillus cereus. Then, the primary cell localization of this nitrite reductase was examined by measuring the enzyme activity of different cellular components from LJ01 cell. After LJ01 was induced by 100 mg/L sodium nitrite solution and treated with lysozyme, the crude enzyme solution of LJ01 was first separated by means of the anion DEAE Sepharose Fast Flow chromatography, and the nitrite degradation activity of fractions a, b and c was measured. Moreover, by using inorganic electron donors such as 0. 1 mol/L succinic acid and sodium sulfite solu- tion, fraction c was identified as a critical nitrite reductase and was separated by Sephadex G-150 column to get pure protein. The identification results show that 0. 54mg of active enzyme protein with an activity of 4004. 89 U/mg can be obtained from 1L of the fermentation liquid, and that the specific NiR activity of the purified enzyme increa- ses by 17.57 folds with a recovery of 2. 37%. In addition, SDS-PAGE results show that the monomer molecular mass of LJ01 is about 30 ku.