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Kochanowski JA, Carroll B, Asp ME, Kaputa EC, Patteson AE. Bacteria Colonies Modify Their Shear and Compressive Mechanical Properties in Response to Different Growth Substrates. ACS Appl Bio Mater 2024. [PMID: 38193703 DOI: 10.1021/acsabm.3c00907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Bacteria build multicellular communities termed biofilms, which are often encased in a self-secreted extracellular matrix that gives the community mechanical strength and protection against harsh chemicals. How bacteria assemble distinct multicellular structures in response to different environmental conditions remains incompletely understood. Here, we investigated the connection between bacteria colony mechanics and the colony growth substrate by measuring the oscillatory shear and compressive rheology of bacteria colonies grown on agar substrates. We found that bacteria colonies modify their own mechanical properties in response to shear and uniaxial compression in a manner that depends on the concentration of agar in their growth substrate. These findings highlight that mechanical interactions between bacteria and their microenvironments are an important element in bacteria colony development, which can aid in developing strategies to disrupt or reduce biofilm growth.
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Affiliation(s)
- Jakub A Kochanowski
- Physics Department and BioInspired Institute, Syracuse University, Syracuse, New York 13210, United States
| | - Bobby Carroll
- Physics Department and BioInspired Institute, Syracuse University, Syracuse, New York 13210, United States
| | - Merrill E Asp
- Physics Department and BioInspired Institute, Syracuse University, Syracuse, New York 13210, United States
| | - Emma C Kaputa
- Physics Department and BioInspired Institute, Syracuse University, Syracuse, New York 13210, United States
| | - Alison E Patteson
- Physics Department and BioInspired Institute, Syracuse University, Syracuse, New York 13210, United States
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Dong Y, Dong H, Feng Z, Wang X, Yao Q, Zhu H. A Disturbed Siderophore Transport Inhibits Myxobacterial Predation. Cells 2022; 11. [PMID: 36496980 DOI: 10.3390/cells11233718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Understanding the intrinsic mechanisms of bacterial competition is a fundamental question. Iron is an essential trace nutrient that bacteria compete for. The most prevalent manner for iron scavenging is through the secretion of siderophores. Although tremendous efforts have focused on elucidating the molecular mechanisms of siderophores biosynthesis, export, uptake, and regulation of siderophores, the ecological aspects of siderophore-mediated competition are not well understood. METHODS We performed predation and bacterial competition assays to investigate the function of siderophore transport on myxobacterial predation. RESULTS Deletion of msuB, which encodes an iron chelate uptake ABC transporter family permease subunit, led to a reduction in myxobacterial predation and intracellular iron, but iron deficiency was not the predominant reason for the decrease in the predation ability of the ∆msuB mutant. We further confirmed that obstruction of siderophore transport decreased myxobacterial predation by investigating the function of a non-ribosomal peptide synthetase for siderophore biosynthesis, a TonB-dependent receptor, and a siderophore binding protein in M. xanthus. Our results showed that the obstruction of siderophores transport decreased myxobacterial predation ability through the downregulation of lytic enzyme genes, especially outer membrane vesicle (OMV)-specific proteins. CONCLUSIONS This work provides insight into the mechanism of siderophore-mediated competition in myxobacteria.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Ritchie LJ, Curtis ER, Murphy KA, Welch RD. Profiling Myxococcus xanthus Swarming Phenotypes through Mutation and Environmental Variation. J Bacteriol 2021; 203:e0030621. [PMID: 34543101 DOI: 10.1128/JB.00306-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myxococcus xanthus is a bacterium that lives on surfaces as a predatory biofilm called a swarm. As a growing swarm feeds on prey and expands, it displays dynamic multicellular patterns such as traveling waves called ripples and branching protrusions called flares. The rate at which a swarm expands across a surface, and the emergence of the coexisting patterns, are all controlled through coordinated cell movement. M. xanthus cells move using two motility systems known as adventurous (A) and social (S). Both are involved in swarm expansion and pattern formation. In this study, we describe a set of M. xanthus swarming genotype-to-phenotype associations that include both genetic and environmental perturbations. We identified new features of the swarming phenotype, recorded and measured swarm expansion using time-lapse microscopy, and compared the impact of mutations on different surfaces. These observations and analyses have increased our ability to discriminate between swarming phenotypes and provided context that allows us to identify some phenotypes as improbable outliers within the M. xanthus swarming phenome. IMPORTANCE Myxococcus xanthus grows on surfaces as a predatory biofilm called a swarm. In nature, a feeding swarm expands by moving over and consuming prey bacteria. In the laboratory, a swarm is created by spotting cell suspension onto nutrient agar in lieu of prey. The suspended cells quickly settle on the surface as the liquid is absorbed into the agar, and the new swarm then expands radially. An assay that measures the expansion rate of a swarm of mutant cells is the first, and sometimes only, measurement used to decide whether a particular mutation impacts swarm motility. We have broadened the scope of this assay by increasing the accuracy of measurements and introducing prey, resulting in new identifiable and quantifiable features that can be used to improve genotype-to-phenotype associations.
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Bradley MD, Neu D, Bahar F, Welch RD. Inter-laboratory evolution of a model organism and its epistatic effects on mutagenesis screens. Sci Rep 2016; 6:38001. [PMID: 27905490 DOI: 10.1038/srep38001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/02/2016] [Indexed: 01/12/2023] Open
Abstract
In theory, a few naturally occurring evolutionary changes in the genome of a model organism may have little or no observable impact on its wild type phenotype, and yet still substantially impact the phenotypes of mutant strains through epistasis. To see if this is happening in a model organism, we obtained nine different laboratories' wild type Myxococcus xanthus DK1622 "sublines" and sequenced each to determine if they had evolved after their physical separation. Under a common garden experiment, each subline satisfied the phenotypic prerequisites for wild type, but many differed to a significant degree in each of the four quantitative phenotypic traits we measured, with some sublines differing by several-fold. Genome resequencing identified 29 variants between the nine sublines, and eight had at least one unique variant within an Open Reading Frame (ORF). By disrupting the ORF MXAN7041 in two different sublines, we demonstrated substantial epistasis from these naturally occurring variants. The impact of such inter-laboratory wild type evolution is important to any genotype-to-phenotype study; an organism's phenotype may be sensitive to small changes in genetic background, so that results from phenotypic screens and other related experiments might not agree with prior published results or the results from other laboratories.
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