中文摘要：

【目的】揭示在低盐浓度条件下榨菜不同盐度腌制体系细菌种群分布及优势菌变化规律,为进一步确定微生物类型与榨菜腌制质量品质之间的相关性提供微生物学基础。【方法】采用16S rDNA基因克隆文库及克隆子分析方法,对5%和7%盐度条件下榨菜腌制体系的微生物多样性、优势种群及其变化规律进行分析。【结果】5%盐度腌制体系的中前期优势种群为乳杆菌属（Lactobacillus）、明串珠菌属（Leuconostoc）和魏斯氏菌属（Weissella）;7%盐度腌制体系的中前期优势乳酸菌为希腊魏斯氏菌（Weissella hellenica）;腌制后期,起主导作用的种群均变成了植物乳杆菌（Lactobacillus plantarum）。在5%盐度腌制条件下pH下降较快,在第10天最低达3.79;而7%盐度条件下,pH变化相对较慢在第20天达最低为4.49,相对应其乳酸菌数量前者生长较快,在第10天达到3.22×108CFU/mL,而在7%盐度条件下乳酸菌数量减少相差近100倍;经腌制3个月的半成品其硝酸盐和亚硝酸盐含量分别在320 mg.kg-1和2.9 mg.kg-1。【结论】采用16S rDNA克隆文库法可检测榨菜低盐腌制过程微生物多样性。低盐条件下腌制pH始终呈下降趋势最后稳定在3.9-4.0;5%盐度腌制较适合乳酸菌的生长,其早期优势菌主要有乳杆菌属、明串珠菌属和魏斯氏菌属;7%盐度时腌制前期优势菌种为希腊魏斯氏菌;最后起主导作用的种群均为植物乳杆菌。低盐腌制后硝酸盐和亚硝酸盐含量显著低于传统高盐腌制工艺,其它无显著差异。

英文摘要：

【Objective】 Microbial community structure,population changes of microorganism and the quality characters of pickled vegetables were investigated,respectively,in order to elucidate the predominant microorganisms involved in pickled processing of mustard tuber under the condition of low salt concentration.【Method】 By means of 16S rDNA clone library and clone units analysis,the microbial diversity,predominant community and its changes were conducted during different fermentation phases at 5% and 7% salinity of pickled mustard tuber.【Result】 The results showed that Lactobacillus,Leuconostoc and Weissella were the predominant community at the early stage of the 5% salt concentration system,but the dominant microorganism at 7% system was Weissella hellenica.At the late phase of pickled processing,Lactobacillus plantarum played a leading role in the pickled system of mustard tuber.In addition,the pH change descended quickly at the 5% salt concentration,reached the lowest value of 3.79 within 10 days,but it reached 4.49 at 7% salt concentration within 20 days.In contrast,the population of lactic acid bacteria increased rapidly at lower salinity,which reached the 3.22×108CFU/mL at the 10th day,the total population of lactic acid bacteria was the 100 times lower compared to that of 7% salinity.The content of nitrate and nitrite in pickled product of three month preservation reached 320 mg·kg-1 and 2.9 mg·kg-1,respectively.【Conclusion】 Microbial diversity of pickled mustard tuber could be investigated by 16S rDNA clone library method.The pH value always descends until a stable level between 3.9 and 4.0.Low salt concentration is benefitical to the growth of lactic acid bacteria and the predominant species are Lactobacillus,Leuconostoc and Weissella at the early phase under the 5% salinity pickling.But the main species become Weissella hellenica at 7% salinity.The crucial microorganism is Lactobacillus plantarum in the stable periods of pickling.The content of nitrate and nitrite in pickled product is great