关于细菌生长速率与趋化运动能力间权衡机制的研究

Growth and motility are two important properties for life. Living organism maintains the reproduction of the species through growth, while motility helps them to search for a suitable environment to grow. However, as both growth and motion consume resources and energy, living organism has to face a tradeoff between them. Chemotaxis, as an important form of motion, bacteria use it to find food, or to flee from poisons. After decades of studies, people have not only gained the knowledge on the molecular mechanism of bacterial chemotaxis, but also realized the trade-off between bacterial growth and the chemotactic ability. However, due to the high complexity of this problem, systematical study about the origin of this trade-off is still missing. In this project, we will quantitatively characterize the relations among the bacterial growth, the chemotaxis related gene expression and the chemotactic ability, reveal the origins and consequence behind, and address how bacteria balance between the growth and motility. This study will gain new knowledge about the bacterial chemotaxis system, discover the interdependence between the bacterial growth and motility, and improve the understanding about the regulations in biological systems.

生长和运动是生物体普遍拥有的重要特征。生物体通过生长繁殖实现物种延续,利用运动寻找适宜生长的环境。但是,生长和运动均需要消耗资源与能量,生物体必须在生长与运动之间权衡。作为运动的一个主要类型，趋化运动是细菌用以趋利避害的主要方式。它的分子机制已经比较清楚。近年来的研究发现了细菌生长与趋化运动间确实存在着相互制约的关系。然而,对于细菌如何实现这种权衡,仍然是个迷团，缺乏系统化的研究。本课题拟通过对细菌生长、趋化运动基因表达和趋化运动能力三者关系的定量研究,揭示其相关性背后的因果关系,探寻细菌面对多变的环境，优化生长速率与维持运动能力的策略。本课题的实施不仅将加深对细菌趋化运动系统的认识,明晰细菌生长与趋化运动间的相互作用关系,更有助于理解复杂生物系统的定量调控机制。

生长和运动是生物体普遍拥有的重要特征。生物体通过生长繁殖实现物种延续,利用趋化运动寻找适宜生长的环境。但是,生长和运动均需要消耗资源与能量,生物体必须在生长与运动之间权衡。本项目围绕该问题，定量了不同稳态细菌生长速率条件下决定细菌趋化运动能力的关键参数：游动速率、转向频率及空间扩张速率等，系统性地研究了细菌生理状态（生长速率）与趋化运动能力之间的关系。本项目发现细菌的趋化运动能力与生长速率之间不存在显著关联，然而，不同生长速率条件影响细菌群体的空间扩张速率，同时，趋化运动能力亦可影响其空间扩张速率。结合最新关于趋化运动对于细菌而言可能来源其空间扩张需求而非觅食的研究报道，我们认为趋化运动能力与生长速率共同决定了其群体空间扩张速率。通过群体空间趋化迁移行为的研究，我们深入探讨了不同趋化运动能力的个体如何实现统一的空间迁移速率。本课题的实施不仅将加深了对细菌趋化运动系统的认识,更有助于理解复杂生物系统的定量调控机制。