婴幼儿配方乳粉及其加工环境中克罗诺杆菌的群体进化与环境耐受性研究

Cronobacter spp. is one of the most dangerous pathogens in powdered infant formula(PIF), which can cause severe neonatal infections with a high fatality rate from 40% to 80%. It is a key prevention and control pathogens in the processing of PIF. However, the widespread distribution of Cronobacter species in the natural environment and its ability to adapt to the environment have become one of the major causes for its frequent contamination in PIF. In the previous study, the applicant found that the Cronobacter species isolated from PIF and its processing environment have rich genetic diversity and tolerance to adverse environments. This study is based on the existing research basis, using whole genome sequencing and bioinformatics analysis techniques to elucidate the evolutionary process of Cronobacter species, and screening genetic function gene about environmental tolerance to constructing regulatory pathways for functional genes. In addition, this study combines the tolerance characteristics of Cronobacter against heat, acid and alkali, dryness, osmotic pressure, antibiotics, ultraviolet rays, disinfectants and antioxidants, etc. to analyze relations and mechanisms between environmental tolerance and the characteristics including biofilm formation, adhesion and invasive, trehalose accumulation and pigment production. The research of this project will provide novel ideas and theoretical basis for the monitoring and prevention of Cronobacter spp. in PIF and infant food.

克罗诺杆菌（Cronobacter spp.）是婴儿配方乳粉（PIF）中最具危害性的致病菌之一，对新生儿的致死率高达40%-80%，是PIF加工过程中重点防控的致病菌之一。然而，克罗诺杆菌在自然界中分布广泛且环境适应能力强，成为其经常污染PIF的主要原因之一。申请者前期研究中发现，分离自婴幼儿配方乳粉及其加工环境中的克罗诺杆菌群体具有丰富的遗传多样性和对不良环境的耐受特性。本项目基于已有的研究基础，采用全基因组测序和生物信息学分析技术，阐述克罗诺杆菌群体进化演变的过程；筛选其环境耐受性的遗传功能基因集，构建功能基因的调控途径；结合克罗诺杆菌对热、酸碱、干燥、渗透压、抗生素、紫外线、消毒剂和抗氧化等的耐受性特点，解析克罗诺杆菌生物膜、粘附和侵入能力、海藻糖合成和色素合成等特性与环境耐受性的关系和机制。通过本项目的研究将为PIF及婴儿食品中克罗诺杆菌的监测和防控提供新的思路和理论基础。

克罗诺杆菌（Cronobacter spp.）是污染婴幼儿配方乳粉（PIF）最具危害性的致病菌之一，其感染新生儿后致死率高达40%-80%。同时，克罗诺杆菌较强的环境适应能力是其经常污染PIF的主要原因。本项目首先对分离自PIF及其加工环境的克罗诺杆菌主要ST型代表菌株的耐热、耐干燥、抗渗性、耐酸碱、耐紫外线、耐微波、耐消毒剂、耐天然抗氧化物以及耐抗生素能力进行评估，结果发现克罗诺杆菌普遍具有较高的耐酸及耐干燥能力。在此基础上，选取15株代表性克罗诺杆菌进行全基因组测序，得到相关基因组的信息及基本特征。同时，将测序数据与参考基因组序列（NCBI中12株参考菌株）进行比对，结合生物学信息分析手段，获得PIF及其加工环境中克罗诺杆菌的变异信息。通过对27株克罗诺杆菌基因组进化的整体分析，构建基于16S rDNA、MLST和全基因组位点的系统发育树，研究克罗诺杆菌属进化过程中核酸分子的衍变过程，以及种间和种内进化发育关系。通过对克罗诺杆菌核心基因组的重组区域进行分析和可移动原件的预测，获得其遗传进化信息。进一步对克罗诺杆菌的泛基因组和基因功能富集进行分析，挖掘其与环境适应性相关的信息，发现其包含多个毒力及环境适应性相关的特有基因及蛋白。本项目采用全基因组测序及生物信息学分析技术等手段，从多个角度开展深入研究，为PIF及婴儿食品中克罗诺杆菌的监测和防控提供新的思路和理论基础。