本篇論文主要從自我推進粒子集體運動的物理和生物方面，探討溶藻弧菌的群游動態、菌落擴張以及細胞分裂。
溶藻弧菌是一種擁有兩種鞭毛馬達系統的海洋細菌，兩種鞭毛馬達分別是單一長在菌體極端由鈉離子驅動的鞭毛（極端鞭毛）和多條分佈在全身的氫離子驅動鞭毛（側邊鞭毛）。當細胞從液體轉換到洋菜膠或粘性較高的介質時，細胞表面的鞭毛數量會增加，在膠體表面有較高的運動性。側邊鞭毛只會在固體表面上表達群游動能性。為了更清楚地了解極端和側邊鞭毛馬達的功能，我們使用三種基因改變的溶藻弧菌：138-2(擁有兩種鞭毛)、VIO5(只有極端鞭毛)、YM19(只有側邊鞭毛)。
在 YM19菌落生長期間，細菌呈現非常多元的運動結構；例如渦流狀、邊界波浪、邊界湧流、塞擠和單層的狀態。在本篇論文中，我們的研究專注於邊界波浪和塞擠狀態。
1.邊界波浪: 當細胞伸長且菌落邊界被限制前進，會有一帶狀區域銜接在被禁止
移動的菌落邊線上做週期擺盪。我們使用粒子影像速度測量(PIV)的計算方法來研究波浪擺盪的機制。波浪擺盪頻率與細胞長度成反比。波浪擺盪是由於細胞的一端被固定於菌落邊線上的自我推進運動。
2. 塞擠狀態: 塞擠狀態是一個很有趣的現象，在菌落內部可以發現具有高密度的單層區域。各個細胞都具有高動能性，但當密度增加時，所有的細菌會形成非移動性向列模式。我們追蹤單一細胞的運動，並計算均方位移(MSD)來研究塞擠形成的過程。塞擠狀態的形成類似於相變的現象。
3. 菌落可以1.03微米/秒的速度迅速擴張。我們發現菌落邊線的移動速度與邊線後面細菌的集體運動有關。我們提出了一個簡單的物理模型來解釋菌落擴張的原因。
4.細胞分裂:群游細胞會抑制細胞分裂。一但將長型細胞轉移到液體環境中，細胞將會分裂回短桿狀。我們設計了一個新的洋菜膠平板系統，在液體中觀察細胞分裂的過程。我們發現細胞能從一端依序分裂，形成正確的大小; 也可以從其他位置分裂成不同大小。

The aim of this thesis is investigating the swarming dynamics of Vibrio alginolyticus from physical and biological aspects of self-propelled particles collective motions, colony expansion and cell division.
Vibrio alginolyticus is a marine bacterium with dual flagellar motor systems which are single Na+ driven polar flagellum and multiple H+ driven lateral flagella. When cells transfer from liquid to agar or high viscosity medium, the number of flagella on the cell surface increases, become highly motile on agar surface. The lateral flagella are expressed for swarm motility on the surface. To give a clear understanding of the functions of polar and lateral flagellar motors, three strains of Vibrio alginolyticus were used: 138-2 ( Pof + Laf + ), VIO5 ( Pof + Laf -), and YM19 ( Pof - Laf + ); wild type with single polar and many lateral filaments, polar only and lateral only, respectively.
During the swarm colony development, YM19 cells shows rich dynamical patterns such as turbulence, edge waving, edge streaming, jamming and mono-layer. In this thesis, I focus on the two collective patterns, edge waving and jamming.
1. Edge waving: The edge waving is happed when the cells are elongated and confined to the edge, a band of cells anchored on the non-moving contact-line show periodic waving. We calculate the velocity by particle image velocimetry (PIV) to study the mechanism of the waving patterns. The waving frequency is inverse proportional to the cell length. The mechanical origin of waving is the self-propelled motion of these cells with one end fixed on the edge of the colony.
2. Jamming: Jamming state is a very interesting phenomenon which can be found at inner region of colony with high density in single layer. Individual cells have high motility but all packed with other neighbors into a non-moving nematic patterns. We track the motion of single cell and calculate the MSD to study the jamming forming process. The jamming state formation is similar to the phase transition phenomenal.
3. The colony could expand rapidly at 1.03 μm/s. We found the local edge moving speed is correlated to the collective motion behind it. There is a high motility active region behind contact line. We propose a colony expanding model based on simple physical mechanism.
4. Cell division: Swarming cells suppress their cell division. Once the cells return to bulk liquid environment, the filamentous cells would return to Planktonic cell type quickly. We design a new agar plate system with bulk liquid environments to observe the dynamical process of cell division in vitro. We found the cells divide with correct size from one end sequentially and also other position of different size.

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