Dataset Information

Density-Dependent Differentiation of Bacteria in Spatially Structured Open Systems.

ABSTRACT: Bacterial quorum sensing is usually studied in well-mixed populations residing within closed systems. The latter do not exchange mass with their surroundings; however, in their natural environment, such as the rhizosphere, bacteria live in spatially structured open systems. Here, we tested the hypothesis that trapping of bacteria within microscopic pockets of an open system triggers density-dependent differentiation. We designed a microfluidic device that trapped swimming bacteria within microscopic compartments. The geometry of the traps controlled their diffusive coupling to fluid flow that played a dual role as nutrient source and autoinducer sink. Bacillus subtilis differentiates into a state of competence in response to quorum sensing and nutrient limitation. Using a mutant strain with a high differentiation rate and fluorescent reporters for competence, we found that the cell density required for differentiation was 100-fold higher than that required in closed systems. A direct comparison of strongly and moderately coupled reservoirs showed that strong coupling supported early differentiation but required a higher number of bacteria for its initiation. Weak coupling resulted in retardation of growth and differentiation. We conclude that spatial heterogeneity can promote density-dependent differentiation in open systems, and propose that the minimal quorum is determined by diffusive coupling to the environment through a trade-off between retaining autoinducers and accessing nutrients.

SUBMITTER: Ribbe J

PROVIDER: S-EPMC4833839 | biostudies-other | 2016 Apr

REPOSITORIES: biostudies-other

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Density-Dependent Differentiation of Bacteria in Spatially Structured Open Systems.

Ribbe Jan J Maier Berenike B

Biophysical journal 20160401 7

Bacterial quorum sensing is usually studied in well-mixed populations residing within closed systems. The latter do not exchange mass with their surroundings; however, in their natural environment, such as the rhizosphere, bacteria live in spatially structured open systems. Here, we tested the hypothesis that trapping of bacteria within microscopic pockets of an open system triggers density-dependent differentiation. We designed a microfluidic device that trapped swimming bacteria within microsc ...[more]

PMID: 27074689

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Project description:Connectivity is a fundamental concept linking dispersal to the emergent dynamics and persistence of spatially structured populations. Functional measures of connectivity typically seek to integrate aspects of landscape structure and animal movement to describe ecologically meaningful connectedness at the landscape and population scale. Despite this focus on function, traditional measures of landscape connectivity assume it is a static property of the landscape, hence abstracting out the underlying spatiotemporal population dynamics. Connectivity is, arguably, a dynamic property of landscapes, and is inherently related to the spatial distribution of individuals and populations across the landscape. Static representations of connectivity potentially overlook this variation and therefore adopting a dynamic approach should offer improved insights about connectivity and associated ecological processes. Using a large-scale, long-term time series of occupancy data from a metapopulation of water voles Arvicola amphibius, we tested competing hypotheses about how considering the dynamic nature of connectivity improves the ability of spatially explicit occupancy models to recover population dynamics. Iteratively relaxing standing assumptions of connectivity metrics, these models ranged from spatially and temporally fixed connectivity metrics that are widely applied, to the more flexible, but lesser used model that allowed temporally varying connectivity measures that incorporate spatiotemporally dynamic patch occupancy states. Our results provide empirical evidence that demographic weighting using patch occupancy dynamics and temporal variability in connectivity measures are important for describing metapopulation dynamics. We highlight the implications of commonly held assumption in connectivity modelling and demonstrate how they result in different and highly variable predictions of metapopulation capacity. Thus, we argue that the concept of connectivity and its potential applications would benefit from recognizing inherent spatiotemporal variation in connectivity that is explicitly linked to underlying ecological state variables.

Dataset Information

Density-Dependent Differentiation of Bacteria in Spatially Structured Open Systems.

Publications

Density-Dependent Differentiation of Bacteria in Spatially Structured Open Systems.

Similar Datasets

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