随着快餐和工业化食品加工日益普及,食品与环境健康问题日益突出。尤其是近年来因致病微生物引起的食物中毒事件频发,也成为食品与环境健康需要关注的问题。外来微生物如何在植物上定植和生存从而引起植物疾病和因生食引起的肠道疾病始终是一个没有彻底解决的问题。虽然经过近十年的研究，外来细菌在强紫外线和干燥等恶劣的叶际环境下及和土著微生物的竞争中如何生存有了一点初步的认识，但是其生存策略及和叶际土著微生物的协同方式这样一个重要的科学问题始终没有一个明确的答案。本课题结合我们课题组的前期工作，利用微生物群体生态学和微生物个体生态技术（individual-based microbial ecology）来回答肠道致病菌在叶际上的生态位和其生存策略。这一课题的完成将提升对外来种群在植物上定植的认识，同时为食品安全和环境健康提供一些基础理论认识。

With the increasing popularity of fast food and the industrialized food processing, food and environmental health issues have become increasingly prominent. Frequent cases of food poisoning caused by pathogenic microorganisms in recent years make it much attention in food and environmental health issues. However, to data, the colonization process and survival strategy of pathogenic bacteria interacting with indigenous bacteria on vegetables and fruits to cause plant diseases and intestinal disease remain poorly unserstood. Even after nearly a decade of research,our knowledge is only limited on thatindigenous bacteria provides a habitat for immigrant bacteria to evade harsh conditions in phyllosphere, such as strong ultraviolet radiation and desiccation.How survival strategy of immigrant bacteria including pathogenic bacteria on phyllosphere, an important scientific issue,has never a clear answer. The subject of this project is to reveal how conditional pathogenic bacteria can survive in phyllosphere based on the technique of individual-based microbial ecology. This kind of scientific answer is important to both the people health who consume fresh fruits and vegetables as well as agricultural production.Meanwhile,this is also important to enhance the understanding of ecological theory in phyllosphere.