Bacteria can reside as multicellular communities held together by a sticky matrix called biofilms. Cells within these structures, like other multicellular organisms, are challenged by unique conditions but technical limitations have hindered developing chemical and physiological descriptions of biofilm microenvironments and cells. This project will elucidate metabolic and signaling mechanisms in specific regions of Pseudomonas aeruginosa biofilms in response to self-generated oxygen limitations and morphological changes. An interdisciplinary approach employing electrochemical and sample processing techniques will enable direct mapping and measurement of metabolites and gene expression. This project will capitalize on the varied patterns and intense coloration of biofilms to pique the interest of local students and the public in the concepts of multicellularity and metabolism, concepts relevant to medicine and industry, through exhibits and workshops. The PI will expand his laboratory course to include design and maintenance of a free website that hosts analytical software and an interactive database for cataloguing biofilm patterns.
Although multicellular life exhibits a seemingly endless array of shapes and patterns, they are morphologically constrained by the metabolic needs of resident cells. Metabolic flexibility can enable energy generation in the chemical gradients that form within such structures; alternatively, cellular communities can change their morphologies to improve access to resources. To address the interplay between metabolism and morphogenesis, this project will explore how self-generated oxygen gradients that form during Pseudomonas aeruginosa biofilm development alter biofilm morphology. Pseudomonas aeruginosa produces redox-active phenazines that can support energy generation when oxygen is limiting and in their absence mutants form intricate wrinkled structures that increase biofilm surface area, and lack an anoxic subzone. This research will interrogate a model in which cells in the anoxic zone carry out phenazine-dependent metabolism and sensor-regulator proteins modulate colony wrinkling in response to redox cues. This project will: i) test whether respiratory enzymes catalyze phenazine reduction in the anoxic zone and require specific respiratory enzymes; ii) test whether biofilm cells couple phenazine reduction to carbon source oxidation or fermentation using chromatography/mass spectrometry of colony thin sections; and iii) define the microenvironmental effects of proteins that control wrinkle formation and identify the matrix protein required to build wrinkled colonies.
