Browsing by Subject "Sociomicrobiology"

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Investigating prokaryotic communities : group activities and physiological heterogeneity
(2013-12) Wessel, Aimee Katherine; Whiteley, Marvin
Bacterial communities engage in social activities, exhibiting behaviors such as communicating with small signaling molecules (quorum sensing [QS]) and building antibiotic-resistant biofilms. The opportunistic human pathogen Pseudomonas aeruginosa produces both freely diffusible QS molecules, as well as a QS molecule that is packaged or transported across cell membranes via the production of outer membrane vesicles. Despite the ubiquity of vesicle production in bacteria, the mechanism of outer membrane vesicle production has not been fully elucidated. In addition, most of our understanding of QS and biofilm formation arises from in vitro studies of bacterial communities containing large numbers of cells, often with greater than 10⁸ bacteria. However, many bacterial communities are comprised of small, densely packed aggregates of cells (≤10⁵ bacteria), and it is unclear how group behaviors and chemical interactions take place in densely packed, small populations. This dissertation has two main goals: i) to provide insights into the mechanism of bacterial membrane vesicle production, and ii) to understand how population size and the spatial distribution of cells affect cell-cell interactions and the nutritional microenvironment within a small (≤10⁵ bacteria) prokaryotic community.
Solution characterization and fabrication of hydrogel microstructures on an optical fiber
(2018-12-04) Myers, Allison Paige; Shear, Jason B.; Brodbelt, Jennifer; Stevenson, Keith; Webb, Lauren
Sociomicrobiology has recently come to the forefront of bioanalytical research, primarily due to its physiological impact in the medical field. The interaction of bacterial cells in small, dense populations can reveal emergent properties of microbial communities, such as increased virulence and pathogenicity, as well as create a more accurate model for bacterial behavior in natural environments. Such systems are particularly relevant in mono- and polymicrobial communities, which exhibit social behaviors as well as the potential for symbiotic and/or adversarial interactions between species. The standard techniques for culturing bacteria lack the tools to provide adequate control over polymicrobial organization on a microscopic scale or to evaluate the spatiotemporal dynamics of bacterial interactions. Using our previously developed micro-3D printing platform, we can arrange cells in biocompatible, pico-liter sized containers, allowing us to overcome these prior spatial limitations. However, key questions still exist regarding the dynamics of interactions between distinct cellular populations. This dissertation focuses on the development of a modified micro-3D printing platform that enables us to fabricate protein-based structures around bacteria on the tip of a moveable substrate. Fabricating structures on moveable substrates such as a glass rod or optical fiber allows us to precisely tune where bacterial clusters are located in relation to varying stimuli and enables delivery of fabricated structures to remote environments such as chronic wounds. However, several challenges were faced in the development of this technique, such as optimization of fabrication solutions, successful layering of hydrogels of varying composition on glass rods, and creation of a custom-built fabrication setup for fabrication on optical fiber tips. Development of these techniques enables us to better appreciate the intricacies of sociomicrobial behavior and interactions, allowing for a better understanding of microbial responses leading to antibiotic resistance, and directing a better approach towards the treatment of various microbial infections.