低盐腌制大头菜腐败菌的分离与初步鉴定

Isolation and identification of specific spoilage from low-salinity pickled turnip

以低盐腌制大头菜为原料,对贮藏、流通期间主要腐败微生物进行分离鉴定。利用微生物学传统分离培养方法从腐败的真空包装低盐腌制大头菜中分离得到菌落形态差异明显的7株细菌、2株酵母。对细菌菌株进行革兰氏染色,同时提取细菌和酵母菌纯培养物基因组DNA,分别进行16S rDNA、26S rDNA的D1/D2序列PCR扩增。测序结果与NCBI中已知序列进行比对和鉴定,发现5株为Bacillus属,1株为Lysinibacillus属,2株为Candida属,1株为非培养细菌的同源菌。经系统发育分析,菌株X5和Lysinibacillus sphaericus的相似性为97%,其余菌株分别与Bacillus sp.,Bacillus subtilis,Bacillus megaterium,Bacillus boroniphilus,Bacillus gibsonii,Uncultured bacterium,Candida pararugosa,Candida zemplinina的相似性为99%-100%。通过微生物生理特性研究及腐败现象分析,推断芽孢杆菌和酵母可能是引起腌制大头菜腐败变质的主要原因。

The spoilage organisms in low-salinity pickled turnip during storage or circulation period were isolated and identified in this experiment. Seven bacteria strains and two yeasts obviously different in colony morphology were screened out following the traditional microbial culture and separation ways. Gram stain was conducted on bacterial strains,and DNA were extracted from the pure culture of bacterium and yeast. The 16S rDNA and 26S rDNA of D1/D2 sequence gene sequencing were amplified. PCR products were sequenced and the results were identified and compared with the closest known sequences from NCBI ,five bacteria were closed to Bacillus genera,one bacteria was closed to Lysinibacillus genera,two bacterias were closed to Candida genera,one bacteria was similar to a reported uncultured bacterium. By phylogenetic analysis,X5 share 97% similarity to Lysinibacillus sphaericus. The other strains shared 99%-100% similarity to Bacillus sp., Bacillus subtilis, Bacillus megaterium, Bacillus boroniphilus, Lysinibacillus sphaericus, Bacillus gibsonfi, Uncultured bacterium, Candida pararugosa, Candida zemplinina. It was speculated that the presence of bacillus and candida might be the major reason for spoilage of low-salinity pickled turnip through physiological ,biochemical characteristic and analysis of corruption.