Competition of neutral bacteria populations in a perfusion system and its statistical physics analysis

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H04033
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Biological physics/Chemical physics/Soft matter physics
• Research Institution: The University of Tokyo (2018-2019); Tokyo Institute of Technology (2016-2017)
• Principal Investigator: Takeuchi Kazumasa 東京大学, 大学院理学系研究科(理学部), 准教授 (50622304)
• Co-Investigator(Kenkyū-buntansha): 若本 祐一 東京大学, 大学院総合文化研究科, 准教授 (30517884)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 生物物理学 / アクティブマター / バクテリア / 微小流体デバイス

Outline of Final Research Achievements

We studied competition of two neutral populations of bacteria cultured in a microfluidic device and characterized its spatiotemporal dynamics from the viewpoint of statistical physics. First we developed a novel, perfusion-type microfluidic device, which allows for long time-lapsed observation of dense bacterial populations under spatially uniform conditions. Using this device, we cultured two strains of Escherichia coli labeled with fluorescent proteins, and found formation of fractal patterns in the regions occupied by the two strains. Analyzing its statistical properties and the nematic order, we proposed a prospective role of topological defects in this problem. We also proposed a theoretical model for bacterial competition. Simulations and theoretical analysis of this model revealed relationship to the voter universality class in non-equilibrium statistical physics.

Free Research Field

統計物理学

Academic Significance and Societal Importance of the Research Achievements

本研究により、本来極めて複雑な存在である生態系や遺伝子集団の統計的変遷についても、中立的な生物種の競合過程については比較的単純な統計物理的概念によって解析や解釈が可能であることが示唆され、生態系、集団遺伝学、統計物理学、アクティブマター物理学等の境界領域に更なる研究の糸口を作ることができた。また、本研究で開発した新たな微小流体デバイス「広域マイクロ灌流系」は、高密度細胞集団が関わる様々な研究課題で有用であろうと期待でき、今後の基礎研究や応用研究に活用され、発展に貢献する可能性がある。