School of Life Sciences, Central China Normal University, Wuhan, China.
School of Life Sciences, Central China Normal University, Wuhan, China
mSphere. 2018 Nov 7;3(6):e00567-18. doi: 10.1128/mSphere.00567-18.
Bacterial cells need to coordinate the cell cycle with biomass growth to maintain cell size homeostasis. For fast-growing bacterial species like and , it is well-known that cell size exhibits a strong dependence on the growth rate under different nutrient conditions (known as the nutrient growth law). However, cell size changes little with slow growth (doubling time of >90 min) for , posing the interesting question of whether slow-growing bacteria species also observe the nutrient growth law. Here, we quantitatively characterize the cell size and cell cycle parameter of a slow-growing bacterium, , at different nutrient conditions. We find that exhibits a threefold change in its cell size when its doubling time varies from 2 h to 6 h. Moreover, the progression rate of its cell cycle is much longer than that of , suggesting a delicate coordination between the cell cycle progression rate and the biomass growth rate. Our study shows that the nutrient growth law holds robustly regardless of the growth capacity of the bacterial species, generalizing its applicability among the bacterial kingdom. The dependence of cell size on growth rate is a fundamental principle in the field of bacterial cell size regulation. Previous studies of cell size regulation mainly focus on fast-growing bacterial species such as and We find here that , a slow-growing bacterium, exhibits a remarkable growth rate-dependent cell size pattern under nutrient limitation, generalizing the applicability of the empirical nutrient growth law of cell size. Moreover, exhibits a much slower speed of cell cycle progression than does, suggesting a delicate coordination between the cell cycle progression rate and the biomass growth rate.
细菌细胞需要将细胞周期与生物量生长相协调，以维持细胞大小的内稳态。对于像 和 这样生长迅速的细菌物种，众所周知，在不同营养条件下（称为营养生长规律），细胞大小与生长速率之间存在很强的依赖性。然而，对于生长缓慢（倍增时间>90 分钟）的 ，细胞大小变化很小，这就提出了一个有趣的问题，即缓慢生长的细菌物种是否也遵循营养生长规律。在这里，我们定量描述了在不同营养条件下，生长缓慢的细菌 ，其细胞大小和细胞周期参数的变化。我们发现，当 倍增时间从 2 小时变化到 6 小时时，其细胞大小会发生三倍的变化。此外，其细胞周期的进展速度比 要慢得多，这表明细胞周期进展速度和生物量生长速度之间存在着微妙的协调关系。我们的研究表明，无论细菌物种的生长能力如何，营养生长规律都具有很强的稳健性，将其适用性推广到了细菌王国。细胞大小与生长速率的依赖性是细菌细胞大小调节领域的一个基本原理。以前关于细胞大小调节的研究主要集中在生长迅速的细菌物种，如 和 。我们在这里发现，生长缓慢的 ，在营养限制下表现出显著的依赖于生长速率的细胞大小模式，将经验性的细胞大小营养生长规律的适用性推广到了该物种。此外， 比 具有更慢的细胞周期进展速度，这表明细胞周期进展速度和生物量生长速度之间存在着微妙的协调关系。
