Sinorhizobium meliloti, a Slow-Growing Bacterium, Exhibits Growth Rate Dependence of Cell Size under Nutrient Limitation.
Sinorhizobium meliloti, a Slow-Growing Bacterium, Exhibits Growth Rate Dependence of Cell Size under Nutrient Limitation.
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苜蓿中华根瘤菌是一种生长缓慢的细菌，在营养限制下表现出细胞大小的生长速率依赖性
DOI：
10.1128/msphere.00567-18
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发表时间：
2018-11-07
期刊：
影响因子：
4.8
通讯作者：
Zhu M
中科院分区：
文献类型：
--
作者：
Dai X;Shen Z;Wang Y;Zhu M
细胞大小依赖于生长速度是细菌细胞大小调控领域的一个基本原理。以往对细胞大小调节的研究主要集中在快速生长的细菌物种，如大肠杆菌和枯草芽孢杆菌。我们发现，在营养限制条件下，生长缓慢的紫花苜蓿根瘤菌表现出显著的细胞大小依赖于生长速率的模式，推广了细胞大小经验营养生长定律的适用性。此外，苜蓿链霉菌的细胞周期进程速度比大肠杆菌慢得多，这表明细胞周期进程速度和生物量增长速度之间存在着微妙的协调。摘要细菌细胞需要协调细胞周期和生物量的生长，以维持细胞大小的动态平衡。对于快速生长的细菌物种，如大肠杆菌和枯草芽孢杆菌，众所周知，在不同的营养条件下，细胞大小强烈依赖于生长速度(称为营养生长定律)。然而，随着大肠杆菌的缓慢生长(~gt；90 分钟的倍增时间)，细胞大小变化不大，这提出了一个有趣的问题，即生长缓慢的细菌物种是否也遵守营养生长规律。在这里，我们定量地表征了一种生长缓慢的细菌--苜蓿中华根瘤菌在不同营养条件下的细胞大小和细胞周期参数。我们发现，当倍增时间从2小时到6小时时，苜蓿链霉菌的细胞大小发生了三倍的变化，而且其细胞周期的进展速度比大肠杆菌的要长得多，这表明细胞周期进展速度和生物量增长速度之间存在着微妙的协调。我们的研究表明，无论细菌种类的生长能力如何，营养生长规律都是成立的，这推广了它在细菌界的适用性。重要性细胞大小依赖于生长速度是细菌细胞大小调节领域的一个基本原理。以往对细胞大小调节的研究主要集中在快速生长的细菌物种，如大肠杆菌和枯草芽孢杆菌。我们发现，在营养限制条件下，生长缓慢的紫花苜蓿根瘤菌表现出显著的细胞大小依赖于生长速率的模式，推广了细胞大小经验营养生长定律的适用性。此外，苜蓿链霉菌的细胞周期进程速度比大肠杆菌慢得多，这表明细胞周期进程速度和生物量增长速度之间存在着微妙的协调。
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 Escherichia coli and Bacillus subtilis. We find here that Sinorhizobium meliloti, 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, S. meliloti exhibits a much slower speed of cell cycle progression than E. coli does, suggesting a delicate coordination between the cell cycle progression rate and the biomass growth rate. ABSTRACT Bacterial cells need to coordinate the cell cycle with biomass growth to maintain cell size homeostasis. For fast-growing bacterial species like Escherichia coli and Bacillus subtilis, 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 E. coli, 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, Sinorhizobium meliloti, at different nutrient conditions. We find that S. meliloti 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 E. coli, 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. IMPORTANCE 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 Escherichia coli and Bacillus subtilis. We find here that Sinorhizobium meliloti, 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, S. meliloti exhibits a much slower speed of cell cycle progression than E. coli does, suggesting a delicate coordination between the cell cycle progression rate and the biomass growth rate.