Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Midreshet Ben-Gurion, Israel.
Department of Mathematics, Bar-Ilan University, 52000 Ramat Gan, Israel.
Phys Rev E. 2022 Jun;105(6-1):064404. doi: 10.1103/PhysRevE.105.064404.
In nature, bacterial collectives typically consist of multiple species, which are interacting both biochemically and physically. Nonetheless, past studies on the physical properties of swarming bacteria were focused on axenic (single-species) populations. In bacterial swarming, intricate interactions between the individuals lead to clusters, rapid jets, and vortices that depend on cell characteristics such as speed and length. In this work, we show the first results of rapidly swarming mixed-species populations of Bacillus subtilis and Serratia marcescens, two model swarm species that are known to swarm well in axenic situations. In mixed liquid cultures, both species have higher reproduction rates. We show that the mixed population swarms together well and that the fraction between the species determines all dynamical scales-from the microscopic (e.g., speed distribution), mesoscopic (vortex size), and macroscopic (colony structure and size). Understanding mixed-species swarms is essential for a comprehensive understanding of the bacterial swarming phenomenon and its biological and evolutionary implications.
在自然界中，细菌群体通常由多个物种组成，这些物种在生化和物理上相互作用。尽管如此，过去关于群体细菌物理特性的研究都集中在无菌（单一物种）种群上。在细菌群体运动中，个体之间复杂的相互作用会导致群体、快速射流和涡旋的产生，而这些又依赖于细胞的特性，如速度和长度。在这项工作中，我们展示了快速游动的枯草芽孢杆菌和粘质沙雷氏菌混合物种群体的首批结果，这两种都是在无菌环境中能很好地进行群体运动的模型物种。在混合液体培养物中，两种物种的繁殖速度都更快。我们表明，混合种群能够很好地一起进行群体运动，而且物种之间的比例决定了所有的动力学尺度——从微观（例如，速度分布）、介观（涡旋大小）到宏观（菌落结构和大小）。理解混合物种群体对于全面理解细菌群体运动现象及其生物学和进化意义至关重要。
