食品污染克罗诺杆菌(阪崎肠杆菌)的分离及鉴定

Isolation and identification of Cronobacter (Enterobacter sakazakii) strains from food

摘要:

摘要:【目的】对300份奶粉样品和50 份非奶粉类食品中克罗诺杆菌的污染情况做定量检测，并对分离得到的克罗诺杆菌进行鉴定。【方法】通过分子方法和9管法对奶粉和其他食品中克罗诺杆菌的污染情况做定量检测;通过吲哚产生、丙二酸盐利用、卫矛醇、肌醇、松三糖和松二糖发酵产酸等六种生化试验对分离株进行鉴定;同时对分离株的16S rRNA基因序列进行同源性分析，通过N-J(Neighbour-Joining)法构建系统发育树。【结果】定量检测结果表明，350份样品中有23 份样品分离出克罗诺杆菌，共分离到24株克罗诺杆菌，检出率为6.6%;23份受污染样品中有4个样品的克罗诺杆菌大于100MPN/100g;24株克罗诺杆菌被鉴定到种或亚种，其中19株为阪崎克罗诺杆菌(Cronobacter sakazakii);2株为丙二酸盐克罗诺杆菌(C．malonaticus);2株为都柏林克罗诺杆菌奶粉亚种(C.dublinensis subsp． lactaridi);1株为莫金斯克罗诺杆菌(C.muytjensii)。【结论】分子方法和9管法联用适合污染率低而定量检测要求高的克罗诺杆菌的奶粉调查;采用生化和分子生物学方法将24 株分离株鉴定到种或亚种，其中阪崎克罗诺杆菌为优势种;奶粉中克罗诺杆菌的污染问题对婴幼儿安全存在隐患，应引起消费者和有关部门的重视。

Abstract:

Abstract:［Objective］This study aimed to detect and quantify Cronobacter in 300 powdered milk samples and 50 nonpowdered milk samples． Totally，24 Cronobacter (formerly Enterobacter sakazakii) strains isolated from powdered milk and other foods were identified and confirmed．［Methods］Cronobacter strains were detected quantitatively using most probable number (MPN) method and molecular detection method． We identified 24 Cronobacter strains using biochemical patterns，including indole production and dulcitol，malonate，melezitose，turanose，and myo-Inositol utilization． Of the 24 strains，their 16S rRNA genes were sequenced，and constructed phylogenetic tree by N-J (Neighbour-Joining) with the 16S rRNA gene sequences of 17 identified Cronobacter strains and 10 non-Cronobacter strains．［Results］ Quantitative detection showed that Cronobacter strains were detected in 23 out of 350 samples yielding 6. 6% detection rate． Twenty-four Cronobacter strains were isolated from 23 samples and the Cronobacter was more than 100 MPN/100g in 4 samples out of 23 samples． The 24 Cronobacter spp． isolates strains were identified and confirmed，including 19 Cronobacter sakazakii strains，2 C． malonaticus strains，2C． dubliensis subsp． lactaridi strains，and 1 C． muytjensii strain．［Conclusion］The combination of molecular detection method and most probable number (MPN) method could be suitable for the detection of Cronobacter in powdered milk，with low rate of contamination and high demand of quantitative detection．24 isolated strains were confirmed and identified by biochemical patterns and molecular technology，and C．sakazakii could be the dominant species．The problem of Cronobacter in powdered milk should be a hidden danger to nurseling，and should catch the government and consumer's attention．