Dong Xiaohui, Li Chengsi, Wu Qingping, Zhang Jumei, Mo Shuping, Guo Weipeng, Yang Xiaojuan, Xu Xiaoke
Guangdong Institute of Microbiology, State Key Laboratory of Applied Microbiology (Ministry-Guangdong Province Jointly Breeding Base), Guangdong Provincial Key Laboratory of South China Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangzhou 510070, China.
Wei Sheng Wu Xue Bao. 2013 May 4;53(5):429-36.
This study aimed to detect and quantify Cronobacter in 300 powdered milk samples and 50 non-powdered milk samples. Totally, 24 Cronobacter (formerly Enterobacter sakazakii) strains isolated from powdered milk and other foods were identified and confirmed.
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.
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, 2 C. dubliensis subsp. lactaridi strains, and 1 C. muytjensii strain.
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.
本研究旨在检测并定量分析300份奶粉样本和50份非奶粉样本中的阪崎肠杆菌。共鉴定并确认了从奶粉和其他食品中分离出的24株阪崎肠杆菌（原称阪崎肠杆菌）菌株。
采用最大可能数（MPN）法和分子检测法对阪崎肠杆菌菌株进行定量检测。我们利用生化特征，包括吲哚产生以及对卫矛醇、丙二酸盐、松三糖、松二糖和肌醇的利用情况，鉴定了24株阪崎肠杆菌菌株。对这24株菌株的16S rRNA基因进行测序，并与17株已鉴定的阪崎肠杆菌菌株和10株非阪崎肠杆菌菌株的16S rRNA基因序列通过邻接法（N-J）构建系统发育树。
定量检测显示，350份样本中有23份检测出阪崎肠杆菌菌株，检出率为6.6%。从23份样本中分离出24株阪崎肠杆菌菌株，其中23份样本中有4份样本中的阪崎肠杆菌含量超过100 MPN/100g。鉴定并确认了24株阪崎肠杆菌属分离菌株，包括19株阪崎肠杆菌菌株、2株丙二酸阪崎肠杆菌菌株、2株都柏林阪崎肠杆菌乳酸亚种菌株和1株穆氏阪崎肠杆菌菌株。
分子检测法与最大可能数（MPN）法相结合适用于奶粉中阪崎肠杆菌的检测，污染率低且定量检测需求高。通过生化特征和分子技术对24株分离菌株进行了确认和鉴定，阪崎肠杆菌可能是优势菌种。奶粉中阪崎肠杆菌问题对婴幼儿应是一种隐患，应引起政府和消费者的关注。
