食品检验中乳酸菌鉴定方法的探讨

Identification methods of lactic acid bacteria in food test

目的评价GB 4789《食品安全国家标准食品微生物学检验》中乳酸菌的鉴定方法。方法选择5种双歧杆菌、4种乳酸杆菌和1种链球菌共10株乳酸菌,分别采用GB 4789标准中的方法、API生化鉴定系统、16S rRNA基因序列分析法和RiboPrinter全自动基因指纹图谱分析法进行鉴定。结果 GB 4789对乳酸杆菌和嗜热链球菌鉴定效果较好,对双歧杆菌的鉴定能力较弱;API鉴定乳酸菌一般至"属"水平;16S rRNA序列分析和RiboPrinter系统可鉴定乳酸菌至"种"水平,婴儿双歧杆菌的鉴定结果为长双歧杆菌婴儿亚种。结论建议GB 4789标准中增加分子生物学方法作为乳酸菌鉴定方法的补充,同时建议及时更新标准中菌株的分类和名称。

Objective To evaluate the identification methods of lactic acid bacteria in GB 4789 Food Microbiological Examination. Methods Ten strains including 5 strains of Bifidobacterium spp., 4 strains of Lactobacillus spp. and 1 strain of Streptococcus spp. were identified by conventional biochemical tests of the national food safety standard, API biochemical system, 16S rRNA sequence analysis and RiboPrinter automatic microbiological gene fingerprint system, respectively. Results Conventional biochemical tests of the standard identified strains with good results of Bifidobacterium and Streptococcus rather than Lactobacillus. API identified strains to the genus level. Both 16S rRNA and RiboPrinter identified strains to the species level and classified Bifidobacterium infantis as Bifidobacterium longum subsp, infantis. Conclusion Molecular method is proposed as a complementary method for identification of lactic acid bacteria in GB 4789. Meanwhile, name and classification of the strains in GB 4789 should be updated timely and accurately.