Intra-colony channel morphology in Escherichia coli biofilms is governed by nutrient availability and substrate stiffness

Bottura, Beatrice and Rooney, Liam M. and Hoskisson, Paul A. and McConnell, Gail (2022) Intra-colony channel morphology in Escherichia coli biofilms is governed by nutrient availability and substrate stiffness. Biofilm, 4. 100084. ISSN 2590-2075 (https://doi.org/10.1016/j.bioflm.2022.100084)

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Abstract

Nutrient-transporting channels have been recently discovered in mature Escherichia coli biofilms, however the relationship between intra-colony channel structure and the surrounding environmental conditions is poorly understood. Using a combination of fluorescence mesoscopy and a purpose-designed open-source quantitative image analysis pipeline, we show that growth substrate composition and nutrient availability have a profound effect on the morphology of intra-colony channels in mature E. coli biofilms. Under all nutrient conditions, intra-colony channel width was observed to increase non-linearly with radial distance from the centre of the biofilm. Notably, the channels were around 25% wider at the centre of carbon-limited biofilms compared to nitrogen-limited biofilms. Channel density also differed in colonies grown on rich and minimal media, with the former creating a network of tightly packed channels and the latter leading to well-separated, wider channels with defined edges. Our approach paves the way for measurement of internal patterns in a wide range of biofilms, offering the potential for new insights into infection and pathogenicity.