食品检测用肠道侵袭性大肠埃希氏菌标准物质的研制
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(中国食品药品检定研究院,北京 100050)

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赵琳娜 女 高级工程师 研究方向为食品微生物 E-mail:jade_zhao@126.com

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科技部“食品安全关键技术研发”重点专项项目(2018YFC1604303)


Preparation of enteroinvasive Escherichia coli reference materials for food analysis
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(National Institutes for Food and Drug Control, Beijing 100050, China)

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    摘要:

    目的 为满足肠道侵袭性大肠埃希氏菌(enteroinvasive Escherichia coli, EIEC)准确检测的实验室质量控制和能力验证需求,研制具有我国自主知识产权、稳定性良好且具有清晰基因组信息背景的即用型EIEC标准物质。方法 利用二代高通量测序技术对EIEC(CMCC 44840)进行全基因组测序,明确CMCC 44840的种属、血清型、多位点序列分型(MLST)和毒力基因;采用冷冻干燥技术制备活菌含量为103 CFU的EIEC冻干样品;参照CNAS-GL017-2018进行均匀性检验,并采用单因素方差分析对结果进行统计分析;将样品分别于-20 ℃、4 ℃、25 ℃和37 ℃条件下保藏,对其储藏稳定性和运输性进行评价;利用5种食品基质样本进行标准物质的使用效果验证,同时组织3家实验室进行协同标定。结果 CMCC 44840基因组大小为4.96 Mb,GC含量为50.7%,编码基因5 424个,种属鉴定结果为大肠埃希氏菌,(Escherichia coli)血清预测结果为O28ac:H7,MLST为ST311型,携带ipaH、virB、virF等毒力基因;制备的EIEC冻干样品均匀性检验结果F=1.79,符合标准物质均匀性要求;冻干样品在25 ℃和4 ℃下保藏7 d,-20 ℃和4 ℃下保藏60 d,菌含量均保持在103CFU水平,在37 ℃下第3 d菌含量出现下降,低于103CFU水平;添加EIEC冻干样品的20件不同食品基质样品经增菌后均检出EIEC;3家协同标定实验室测定EIEC冻干样品菌含量均为103 CFU,且实验室间无显著性差异(F=0.59)。结论 本研究所制备的EIEC标准物质所用菌株具有清晰的基因组序列信息,均匀性和稳定性均符合要求,适用性良好,能够满足食品检测实验室的质量控制和能力验证的需求。

    Abstract:

    Objective To satisfy the demands of laboratory quality control and proficiency testing for the detection of enteroinvasive Escherichia coli (EIEC), a stable EIEC reference material was developed with independent intellectual property rights, good stability and clear background genomic information. Methods NGS Technique was used to sequence the whole genome of enteroinvasive Escherichia coli (CMCC 44840), bioinformatics analysis was performed to identify the species, serotype, MLST type and virulence genes; EIEC lyophilized samples with 103 CFU were prepared by freeze-drying method ; The homogeneity test was performed according to CNAS-GL017, and the result were statistically analyzed by one-way ANOVA; The samples were stored at -20,4, 25 and 37 ℃, respectively, and their storage stability and transport stability were evaluated; Five kinds of food matrix samples were used to verify the applicability of reference materials, and three laboratories were organized for collaborative calibration. Results The genome size of CMCC 44840 was 4.96 Mb, the GC content was 50.7%, and the genome contained 5424 coding genes. This strain was identified as the species of Escherichia coli, and the serotype and the MLST type were predicted to be O28ac:H7 and ST311, respectively, and it carried ipaH, virB, virF and other virulence genes. The homogeneity test result of the EIEC lyophilized sample was F=1.79, which met the homogeneity requirements of reference materials. The EIEC samples were still 103 CFU when storing at -20 ℃ and 4 ℃ for 60 d and storing at 25 ℃ and 4 ℃ for 7 d, and decreased on the third day at 37 ℃. EIEC were detected in 20 different food matrix samples with EIEC lyophilized samples after enrichment. The samples were 103 CFU determined by three collaborative calibration laboratories, and there were no significant differences among these laboratories (F=0.59). Conclusion The EIEC reference material prepared in this study has clear genome sequence information. The homogeneity and stability meet the requirements and have good applicability, which can meet the requirements of quality control and capability verification in food testing laboratory.

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赵琳娜,王学硕,刘娜,崔生辉,路勇.食品检测用肠道侵袭性大肠埃希氏菌标准物质的研制[J].中国食品卫生杂志,2021,33(6):807-814.

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  • 收稿日期:2021-09-30
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  • 在线发布日期: 2022-01-04
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