需钠弧菌细胞大小及细胞周期与生长偶联的定量模式研究

细菌需要将细胞周期与生长偶联进而维持稳定的细胞大小。已有的关于细菌细胞周期的研究主要集中在含有单条染色体的细菌细胞，对双染色体细菌涉及较少。需钠弧菌是目前已知的增殖速度最快的细菌（快至10分钟一代）。它包含一长一短两条染色体，是潜在的新一代微生物工程菌。然而关于该细菌如何将细胞周期与快速生长进行偶联的机制尚不清楚。在前期研究中，申请人课题组测定了需钠弧菌在多种培养条件下的生长速率，同时确定了其长染色体的复制起始位点。此外申请人发现，营养限制与渗透压胁迫可以显著影响需钠弧菌的细胞大小。本项目将结合分子微生物学与定量生物学等手段研究需钠弧菌如何协调长染色体与短染色体的复制。在此基础上，研究在不同生长逆境下，需钠弧菌细胞大小、细胞周期以及生长速率三者之间的定量偶联模式，进而从全局角度理解双染色体细菌细胞周期的调控模式，为未来需钠弧菌的工业化、基因工程以及合成生物学应用提供理论依据。

Bacterial cell needs to coordinate cell cycle progression with biomass growth to maintain cell size hemostasis. Previous studies on bacterial cell cycle mainly focus on bacteria species containing single chromosome. However, little studies focus on bacteria containing two chromosomes. To our knowledge, Vibrio natriegens is the fastest-growing bacteria species known with a generation time being as short as 10 min. It contains two chromosomes, a long one and a short one, and is a potential new-generation host bacterium for microbial bioengineering. However, it remains unclear how it manages to coordinate the cell cycle with its rapid growth. In preliminary studies, we have measured the growth rate of V. natriegens under various growth conditions and have also identified the replication origin of its long chromosome. In addition, we found that nutrient limitation and osmotic stress could significantly affect its cell size. Combing molecular microbiology and quantitative biology approaches, this research aims to investigate how the fast-growing V. natriegens manages to coordinate the replication of the long chromosome and short chromosome. Based on this, we will further quantitatively study the coordination mode of cell size, cell cycle with growth rate of V. natriegens under different stress conditions. This research will help us gain a global insight into the mode of cell cycle regulation of bacteria species containing two chromosomes, further laying the theoretical foundation for the future application of V. natriegens on microbial industrialization, genetic engineering and synthetic biology.