title: Self-organization of bacterial communities against environmental pH variation: Controlled chemotactic motility arranges cell population structures in biofilms.
abstract: As with many living organisms, bacteria often live on the surface of solids, such as foods, organisms, buildings and soil. Compared with dispersive behavior in liquid, bacteria on surface environment exhibit significantly restricted mobility. They have access to only limited resources and cannot be liberated from the changing environment. Accordingly, appropriate collective strategies are necessarily required for long-term growth and survival. However, in spite of our deepening knowledge of the structure and characteristics of individual cells, strategic self-organizing dynamics of their community is poorly understood and therefore not yet predictable. Here, we report a morphological change in Bacillus subtilis biofilms due to environmental pH variations, and present a mathematical model for the macroscopic spatio-temporal dynamics. We show that an environmental pH shift transforms colony morphology on hard agar media from notched 'volcano-like' to round and front-elevated 'crater-like'. We discover that a pH-dependent dose-response relationship between nutritional resource level and quantitative bacterial motility at the population level plays a central role in the mechanism of the spatio-temporal cell population structure design in biofilms.
authors.affiliation: Frontier Research Institute for Interdisciplinary Sciences (FRIS), Tohoku University, Sendai, Japan.|Graduate School of Science, Tohoku University, Sendai, Japan.
authors.forename: Sohei
authors.identifier: http://orcid.org/0000-0002-4259-0075
authors.initials: S
authors.lastname: Tasaki
authors.affiliation: Sendai National College of Technology, Natori, Japan.
authors.forename: Madoka
authors.initials: M
authors.lastname: Nakayama
authors.affiliation: Frontier Research Institute for Interdisciplinary Sciences (FRIS), Tohoku University, Sendai, Japan.|Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Shoji
mesh_terms: D018407:Bacterial Physiological Phenomena; D018441:Biofilms; D002633:Chemotaxis; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological