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Asp ME, Ho Thanh MT, Germann DA, Carroll RJ, Franceski A, Welch RD, Gopinath A, Patteson AE. Spreading rates of bacterial colonies depend on substrate stiffness and permeability. PNAS NEXUS 2022; 1:pgac025. [PMID: 36712798 PMCID: PMC9802340 DOI: 10.1093/pnasnexus/pgac025] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/25/2022] [Accepted: 03/09/2022] [Indexed: 02/01/2023]
Abstract
The ability of bacteria to colonize and grow on different surfaces is an essential process for biofilm development. Here, we report the use of synthetic hydrogels with tunable stiffness and porosity to assess physical effects of the substrate on biofilm development. Using time-lapse microscopy to track the growth of expanding Serratia marcescens colonies, we find that biofilm colony growth can increase with increasing substrate stiffness, unlike what is found on traditional agar substrates. Using traction force microscopy-based techniques, we find that biofilms exert transient stresses correlated over length scales much larger than a single bacterium, and that the magnitude of these forces also increases with increasing substrate stiffness. Our results are consistent with a model of biofilm development in which the interplay between osmotic pressure arising from the biofilm and the poroelastic response of the underlying substrate controls biofilm growth and morphology.
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Affiliation(s)
- Merrill E Asp
- Physics Department, Syracuse University, Syracuse, NY 13244, USA,BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Minh-Tri Ho Thanh
- Physics Department, Syracuse University, Syracuse, NY 13244, USA,BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Danielle A Germann
- Physics Department, Syracuse University, Syracuse, NY 13244, USA,BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Robert J Carroll
- Physics Department, Syracuse University, Syracuse, NY 13244, USA,BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Alana Franceski
- BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA,Biology Department, Syracuse University, Syracuse, NY 13244, USA
| | - Roy D Welch
- BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA,Biology Department, Syracuse University, Syracuse, NY 13244, USA
| | - Arvind Gopinath
- Department of Bioengineering, University of California, Merced, Merced, CA 95343, USA,Health Sciences Research Institute, University of California, Merced, Merced, CA 95343, USA
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MOLLER V, REYN A. A NEW SOLID MEDIUM FOR THE ISOLATION OF NEISSERIA GONORRHOEAE. Bull World Health Organ 1965; 32:471-6. [PMID: 14315717 PMCID: PMC2555269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
Biological products have been widely used in media intended for the primary isolation of Neisseria gonorrhoeae. Most of these substances are expensive and, in some places, difficult to procure. Ascitic fluid, which has been extensively used, is becoming increasingly rare. On the other hand, attempts to replace these biological substances by chemical compounds have met with little success, and a satisfactory synthetic medium does not exist. The authors describe the laboratory preparation of a reproducible medium which does not contain any fresh biological substances. It was developed from a routine "chocolate medium" which contained ascitic fluid and heated horse blood. Experiments with sparsely growing fresh laboratory strains showed that the ascitic fluid could be replaced by a combination of yeast and liver autolysates and the horse blood by haemoglobin. This Haemoglobin-Yeast-Liver (HYL) medium proved to be well suited for the primary isolation of N. gonorrhoeae and preliminary experiments indicated that it might also be suitable for use as a reference medium in sensitivity determinations. Attempts to use yeast and liver autolysates to replace ascitic fluid in a fermentation medium which did not contain blood or haemoglobin were less successful. Germination on the modified medium was relatively poor and it seems that the addition of a protective agent, such as albumin or starch, will be necessary.
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