Dataset Information

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.

SUBMITTER: Tasaki S

PROVIDER: S-EPMC5333884 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Self-organization of bacterial communities against environmental pH variation: Controlled chemotactic motility arranges cell population structures in biofilms.

Tasaki Sohei S Nakayama Madoka M Shoji Wataru W

PloS one 20170302 3

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 ...[more]

PMID: 28253348

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Project description:Labrenzia aggregata LZB033 (Rhodobacteraceae), which produces dimethylsulfoniopropionate (DMSP) and reduces nitrate to nitrogen, was isolated from seawater of the East China Sea. Its genome encodes a large number of transcriptional regulators which may be important for its adaptation to diverse marine environments. The alternative σ54 factor (RpoN) is a central regulator of many bacteria, regulating the transcription of multiple genes and controlling important cellular functions. However, the exact role of RpoN in Labrenzia spp. is unknown. In this study, an in-frame rpoN deletion mutant was constructed in LZB033, and the function of RpoN was determined. To systematically identify RpoN-controlled genes, we performed a detailed analysis of gene expression differences between the wild-type strain and the ΔrpoN mutant using RNA sequencing. The expression of 175 genes was shown to be controlled by RpoN. Subsequent phenotypic assays showed that the ΔrpoN mutant was attenuated in flagellar biosynthesis and swimming motility, utilized up to 13 carbon substrates differently, lacked the ability to assimilate malic acid, and displayed markedly decreased bioﬁlm formation. In addition, stress response assays showed that the ΔrpoN mutant was impaired in the ability to survive under different challenge conditions, including osmotic stress, oxidative stress, temperature changes, and acid stress. Moreover, both the DMSP synthesis and catabolism rates of LZB033 decreased after rpoN was knocked out. Our work provides essential insight into the regulatory function of RpoN, revealing that RpoN is a key determinant for LZB033 flagellar formation, motility, biofilm formation, and environmental fitness, as well as DMSP production and degradation.IMPORTANCE This study established an in-frame gene deletion method in the alphaproteobacterium Labrenzia aggregata LZB033 and generated an rpoN gene mutant. A comparison of the transcriptomes and phenotypic characteristics between the mutant and wild-type strains confirmed the role of RpoN in L. aggregata LZB033 flagellar formation, motility, biofilm formation, and carbon usage. Most importantly, RpoN is a key factor for survival under different environmental challenge conditions. Furthermore, the ability to synthesize and metabolize dimethylsulfoniopropionate (DMSP) was related to RpoN. These features revealed RpoN to be an important regulator of stress resistance and survival for L. aggregata LZB033 in marine environments.

Dataset Information

Self-organization of bacterial communities against environmental pH variation: Controlled chemotactic motility arranges cell population structures in biofilms.

Publications

Self-organization of bacterial communities against environmental pH variation: Controlled chemotactic motility arranges cell population structures in biofilms.

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