中文摘要：

研究了发酵红皮萝卜中细菌和大肠杆菌数量与亚硝酸盐含量变化的规律,从中分离得到10株菌株,通过硝酸盐还原能力的测定,筛选出9株具有硝酸盐还原能力的菌株,其中E5和E6两个菌株硝酸盐还原能力最强,并测定了2个菌株硝酸还原酶（NR）的酶活及pH对酶活的影响。进而对筛选的E5、E6两个菌株进行了分子生物学鉴定。结果表明,E5为阴沟肠杆菌（Enterobacter cloacae）,E6为克雷伯氏菌（Klebsiella oxytoca）。

英文摘要：

The relationship between the number of bacteria, Escherichia coli and nitrite was studied. Total ten bacteria strains were isolated from fermented radish, wherein nine nitrrate reducing bacteria were screened by the determination of conversion ability of nitrate to nitrite. Among them, the strains E5 and E6 had the highest nitrate reducing activity. Furthermore, nitrate reductase activity of these two strains and the influence of pH on such activity were analysed. According to the biochemical and molecular identification, E5 was identified as Enterobacter cloacae and E6 was Klebsiella oxytoca.