所謂的細菌群泳是(長)桿狀細菌在類固體上的一種快速大規模遷徙。基於 群泳依賴於群體感知的基本知識，以及在此之前發生的一系列分化，包括細 胞伸長和側鞭毛增加，先前的研究使用不同的突變菌株來獨立地操縱細胞的 長寬比。儘管一些研究試圖透過混合兩種不同的物種或菌株來創造一個更接 近自然群集條件的環境，但他們低估並忽略了個體差異中細胞大小對動力學 的影響。
因此，在本研究中，我們提出了一個引人入勝問題，即單一菌株中多種 尺寸的細菌的演化優勢為何。為了解決這個問題，我們使用絲狀細菌菌株 Vibrio alginolyticus (YM19) 實驗研究其單層群泳動力學。它們巨大的個體長 度差異使我們能夠在個別追蹤後將它們分為五個長度組。研究發現，具有異 質分佈的較長細胞會對齊鄰居並建立群泳團簇，快速且持久地導航。同時， 相對均勻分佈的較短細菌容易受到鄰居的影響，所形成的區域就像不同群泳 團簇之間的緩衝區，間接輔助群泳團簇導航並防止堵塞。因此，在同一菌株 內，不同長度的細菌在同一生態位中發揮不同的作用。

Bacterial swarming is a rapid mass migration of rod-like bacteria on the semi-solid. Based on the fundamental knowledge that swarming is quorum sensing dependent, and a series differentiation including the elongation and increased lateral flagella happens before swarming, previous studies used differ- ent mutated strains to manipulate the aspect ratios of cells, separately. Despite some studies attempting to create an environment closer to nature-swarming conditions by mixing two different species and strains, they underestimate and disregard the individual variants in cell sizes.
In this work, we raise an intriguing question about what the evolutionary advantage takes place in multi-sizes of bacteria in a single strain. To unravel this issue, we experimentally investigated the monolayer swarming dynamics using a filamentous bacteria strain Vibrio alginolyticus (YM19). Their vast in- dividual variant in lengths enable us to categorize them into five length groups, after individual tracing. It is found that the longer cells with heterogeneous distribution align the neighbors and structure the swarming clusters to navigate rapidly and persistently; meanwhile, the shorter cells in homogeneous distribution are easily affected by the neighbors, which act like the buffer between different swarming clusters indirectly assist the navigation of swarming and prevent jamming. Therefore, within the same strain, the bacteria in different lengths play different roles in the same niche.

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