Bacterial social interactions drive the emergence of differential spatial colony structures

Abstract

BackgroundSocial interactions have been increasingly recognized as one of the major factors that contribute to the dynamics and function of bacterial communities. To understand their functional roles and enable the design of robust synthetic consortia, one fundamental step is to determine the relationship between the social interactions of individuals and the spatiotemporal structures of communities.ResultsWe present a systematic computational survey on this relationship for two-species communities by developing and utilizing a hybrid computational framework that combines discrete element techniques with reaction-diffusion equations. We found that deleterious interactions cause an increased variance in relative abundance, a drastic decrease in surviving lineages, and a rough expanding front. In contrast, beneficial interactions contribute to a reduced variance in relative abundance, an enhancement in lineage number, and a smooth expanding front. We also found that mutualism promotes spatial homogeneity and population robustness while competition increases spatial segregation and population fluctuations. To examine the generality of these findings, a large set of initial conditions with varying density and species abundance was tested and analyzed. In addition, a simplified mathematical model was developed to provide an analytical interpretation of the findings.ConclusionsThis work advances our fundamental understanding of bacterial social interactions and population structures and, simultaneously, benefits synthetic biology for facilitated engineering of artificial microbial consortia.Electronic supplementary materialThe online version of this article (doi:10.1186/s12918-015-0188-5) contains supplementary material, which is available to authorized users.

Characterisation and comparison of the microflora of traditional and pure culturexiaoquduring thebaijiuliquor brewing process

“…Because the liquor brewing process was performed in an open environment with spontaneous fermentation, environmental factors will have an influence on the entire liquor brewing process . Within the complex microbial consortia, bacterial interactions are widespread and are likely to affect the microbial community . The variation in relative abundance between LAB ( Lactobacillus and Lactococcus ) and Bacillus were different.…”

Intercellular adhesion promotes clonal mixing in growing bacterial populations

“…Self-organizing processes within bacterial populations are driven by a multitude of local chemical and physical interactions. Chemical interactions underpin a range of mechanisms such as mutualism and competition, and several studies have demonstrated their effects on the spatial organization of bacterial populations [ 23 – 25 ]. It is spatial constraint however, that is a defining aspect of surface growth, with bacteria growing in close physical proximity.…”

Functional channels in matureE. colicolonies

“…Growth of two isogenic strains in co-culture, each expressing a different photoprotein, two strains formed sectors as has been previously described 18–20,22,21,23 . We wished to explore this sectoring property in the context of intra-colony channel formation and to determine if the channels were shared between the strains.…”

“…Upon first glance, channels resemble fractal features found in multi-strain colonies which form as a result of the mechanical instability between growth and viscous drag of dividing cells 19 . However, these features have only been reported in multi-strain colonies where the fractal dendrites have been composed of live, fluorescing cells 20–23,47 . We demonstrate that the spatial patterns we observe are different to those outlined previously.…”