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Title: Single microcolony diffusion analysis in Pseudomonas aeruginosa biofilms
Authors: Sankaran, Jagadish
Tan, Nicholas John Jie Hao
But, Ka Pui
Cohen, Yehuda
Rice, Scott A.
Wohland, Thorsten
Keywords: Science::Biological sciences
Issue Date: 2019
Source: Sankaran, J., Tan, N. J. J. H., But, K. P., Cohen, Y., Rice, S. A., & Wohland, T. (2019). Single microcolony diffusion analysis in Pseudomonas aeruginosa biofilms. npj Biofilms and Microbiomes, 5(1), 35-. doi:10.1038/s41522-019-0107-4
Journal: npj Biofilms and Microbiomes
Abstract: The influence of the biofilm matrix on molecular diffusion is commonly hypothesized to be responsible for emergent characteristics of biofilms such as nutrient trapping, signal accumulation and antibiotic tolerance. Hence quantifying the molecular diffusion coefficient is important to determine whether there is an influence of biofilm microenvironment on the mobility of molecules. Here, we use single plane illumination microscopy fluorescence correlation spectroscopy (SPIM-FCS) to obtain 3D diffusion coefficient maps with micrometre spatial and millisecond temporal resolution of entire Pseudomonas aeruginosa microcolonies. We probed how molecular properties such as size and charge as well as biofilm properties such as microcolony size and depth influence diffusion of fluorescently labelled dextrans inside biofilms. The 2 MDa dextran showed uneven penetration and a reduction in diffusion coefficient suggesting that the biofilm acts as a molecular sieve. Its diffusion coefficient was negatively correlated with the size of the microcolony. Positively charged dextran molecules and positively charged antibiotic tobramycin preferentially partitioned into the biofilm and remained mobile inside the microcolony, albeit with a reduced diffusion coefficient. Lastly, we measured changes of diffusion upon induction of dispersal and detected an increase in diffusion coefficient inside the biofilm before any loss of biomass. Thus, the change in diffusion is a proxy to detect early stages of dispersal. Our work shows that 3D diffusion maps are very sensitive to physiological changes in biofilms, viz. dispersal. However, this study also shows that diffusion, as mediated by the biofilm matrix, does not account for the high level of antibiotic tolerance associated with biofilms.
ISSN: 2055-5008
DOI: 10.1038/s41522-019-0107-4
Rights: © 2019 The Author(s). Published in partnership with Nanyang Technological University. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit
Fulltext Permission: open
Fulltext Availability: With Fulltext
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