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, 52900, Ramat-Gan, Israel.
Sci Rep. 2022 Oct 3;12(1):16500. doi: 10.1038/s41598-022-20644-3.
Bacterial swarms are a highly-researched example of natural active matter. In particular, the interplay between biological interactions and the physics underlying the swarming dynamics is of both biological and physical interest. In this paper, we study mixed swarms of Bacillus subtilis and Pseudomonas aeruginosa. We find intricate interactions between the species, showing both cooperation and segregation across different spatial and temporal scales. On one hand, even though axenic colonies grow on disparate time scale, an order of magnitude apart, the two-species swarm together, forming a single, combined colony. However, the rapidly moving populations are locally segregated, with different characteristic speeds and lengths (or cluster sizes) that depend on the ratio between the species. Comparison with controlled mutant strains suggest that both the physical and known biological differences in species characteristics may not be enough to explain the segregation between the species in the mixed swarm. We hypothesize that the heterogeneous spatial distribution is due to some mechanism that enables bacteria to recognize their own kind, whose precise origin we could not identify.
细菌群集是自然活性物质的一个研究热点。特别是，生物相互作用和 swarm 动力学的物理基础之间的相互作用既有生物学意义，也有物理意义。在本文中，我们研究了枯草芽孢杆菌和铜绿假单胞菌的混合 swarm。我们发现了物种之间复杂的相互作用，表现出不同空间和时间尺度上的合作和隔离。一方面，尽管单一种群的菌落生长时间尺度相差一个数量级，但两种细菌 swarm 在一起，形成了一个单一的、组合的菌落。然而，快速移动的种群在局部是隔离的，具有不同的特征速度和长度（或簇大小），这取决于物种的比例。与受控的突变株的比较表明，物种特征的物理和已知生物学差异可能不足以解释混合 swarm 中物种之间的隔离。我们假设这种不均匀的空间分布是由于某种机制使细菌能够识别自己的种类，而我们无法确定这种机制的确切来源。
