Bacteria have been reported to exhibit complicated morphological colony patterns on solid media, depending on intracellular, and extracellular factors such as motility, cell propagation, and cell-cell interaction. We isolated the filamentous cyanobacterium, Pseudanabaena sp. NIES-4403 (Pseudanabaena, hereafter), that forms scattered (discrete) migrating colonies on solid media. While the scattered colony pattern has been observed in some bacterial species, the mechanism underlying such a pattern still remains obscure. We studied the morphology of Pseudanabaena migrating collectively and found that this species forms randomly scattered clusters varying in size and further consists of a mixture of comet-like wandering clusters and disk-like rotating clusters. Quantitative analysis of the formation of these wandering and rotating clusters showed that bacterial filaments tend to follow trajectories of previously migrating filaments at velocities that are dependent on filament length. Collisions between filaments occurred without crossing paths, which enhanced their nematic alignments, giving rise to bundle-like colonies. As cells increased and bundles aggregated, comet-like wandering clusters developed. The direction and velocity of the movement of cells in comet-like wandering clusters were highly coordinated. When the wandering clusters entered into a circular orbit, they turned into rotating clusters, maintaining a more stable location. Disk-like rotating clusters may rotate for days, and the speed of cells within a rotating cluster increases from the center to the outmost part of the cluster. Using a mathematical modeling with simplified assumption we reproduced some features of the scattered pattern including migrating clusters. Based on these observations, we propose that Pseudanabaena forms scattered migrating colonies that undergo a series of transitions involving several morphological patterns. A simplified model is able to reproduce some features of the observed migrating clusters.

中文翻译：

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丝状蓝细菌 Pseudanabaena sp. 中分散的迁移菌落形成。NIES-4403

据报道，细菌在固体培养基上表现出复杂的形态菌落模式，这取决于细胞内和细胞外因素，如运动性、细胞增殖和细胞间相互作用。我们分离出丝状蓝细菌，假单胞菌属。NIES-4403（Pseudanabaena，以下简称），在固体培养基上形成分散的（离散的）迁移菌落。虽然在一些细菌物种中观察到分散的菌落模式，但这种模式背后的机制仍然不清楚。我们研究了Pseudanabaena集体迁徙的形态，发现该物种形成大小不等的随机分散的星团，进一步由彗星状游走星团和盘状旋转星团的混合物组成。对这些漂移和旋转簇形成的定量分析表明，细菌细丝倾向于以取决于细丝长度的速度跟随先前迁移细丝的轨迹。细丝之间的碰撞发生在没有交叉路径的情况下，这增强了它们的向列排列，产生了束状菌落。随着细胞的增加和束的聚集，形成了彗星状的游荡星团。彗星状游走星团中细胞运动的方向和速度高度协调。当游荡的星团进入圆形轨道时，它们变成了旋转的星团，保持了更稳定的位置。圆盘状的旋转星团可能会旋转数天，旋转星团内的细胞速度从星团的中心向最外层逐渐增加。使用具有简化假设的数学模型，我们再现了分散模式的一些特征，包括迁移集群。基于这些观察，我们提出假单胞菌形成分散的迁移菌落，这些菌落经历了一系列涉及几种形态模式的转变。一个简化的模型能够重现观察到的迁移集群的一些特征。