Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Curr Biol. 2022 Jul 25;32(14):3059-3069.e7. doi: 10.1016/j.cub.2022.06.011. Epub 2022 Jun 30.
Facultative multicellular behaviors expand the metabolic capacity and physiological resilience of bacteria. Despite their ubiquity in nature, we lack an understanding of how these behaviors emerge from cellular-scale phenomena. Here, we show how the coupling between growth and resource gradient formation leads to the emergence of multicellular lifecycles in a marine bacterium. Under otherwise carbon-limited growth conditions, Vibrio splendidus 12B01 forms clonal multicellular groups to collectively harvest carbon from soluble polymers of the brown-algal polysaccharide alginate. As they grow, groups phenotypically differentiate into two spatially distinct sub-populations: a static "shell" surrounding a motile, carbon-storing "core." Differentiation of these two sub-populations coincides with the formation of a gradient in nitrogen-source availability within clusters. Additionally, we find that populations of cells containing a high proportion of carbon-storing individuals propagate and form new clusters more readily on alginate than do populations with few carbon-storing cells. Together, these results suggest that local metabolic activity and differential partitioning of resources leads to the emergence of reproductive cycles in a facultatively multicellular bacterium.
兼性多细胞行为扩展了细菌的代谢能力和生理弹性。尽管它们在自然界中无处不在，但我们仍不了解这些行为是如何从细胞尺度的现象中出现的。在这里，我们展示了生长和资源梯度形成之间的耦合如何导致海洋细菌中出现多细胞生命周期。在其他条件下受碳限制的生长条件下，灿烂弧菌 12B01 形成克隆多细胞群体，从褐藻多糖褐藻酸盐的可溶性聚合物中集体收获碳。随着它们的生长，群体表型上分化为两个空间上不同的亚群：围绕着运动、储存碳的“核心”的静态“壳”。这两个亚群的分化与集群内氮源可用性梯度的形成同时发生。此外，我们发现含有大量储存碳个体的细胞群体在褐藻酸盐上比含有少量储存碳细胞的群体更容易繁殖和形成新的群体。总之，这些结果表明，局部代谢活性和资源的差异分配导致了兼性多细胞细菌中生殖周期的出现。
