Interdependency of chemical, structural, and physiological heterogeneity in Pseudomonas aeruginosa biofilms

Columbia Univ New York Morningside, New York NY

Investigators

Abstract

PROJECT SUMMARY Bacterial infections constitute a major burden on healthcare systems globally. One of the reasons these diseases are difficult to treat is that most antibiotics act specifically on rapidly growing cells, but bacteria in many types of infections grow slowly and exist in static aggregates. Our long-term goal is to define the integrated molecular pathways that support survival of bacteria in aggregates that contain chemical gradients, with a focus on the opportunistic pathogen Pseudomonas aeruginosa. To investigate multicellular physiology and spatial organization, we employ standardized models in which aggregates are grown suspended in a supplied polymer matrix, or at interfaces with air where they produce their own matrix and form structures called biofilms. The main hypothesis driving our work is that cells in developing aggregates respond to, and affect the distribution of, metabolic cues that affect physiological differentiation, and that these activities support population robustness and survival in infection sites. This project will focus on P. aeruginosa lactate metabolism and self-resistance to cyanide (a P. aeruginosa virulence factor) because the associated pathways contribute to bacterial survival and multicellular physiology. We will use basic molecular approaches combined with newly developed and innovative techniques, including imaging mass spectrometry and live microscopic analysis of biofilms, to address questions regarding the modulation of metabolic pathways in response to chemical cues and an endogenous toxin, the regulation of spatial patterning at the cellular level, and the effects of microanatomy on biofilm physiology: (1) How do biofilm and infection-site conditions and co-occurring bacteria affect P. aeruginosa’s use of lactate, a major carbon source available within hosts? (2) How does P. aeruginosa tolerate its own production of cyanide? (3) How is cellular organization established, and what are the consequences of cell patterning for metabolic differentiation within biofilms? As P. aeruginosa is a major cause of infections in hospitals, in burn and surgical-site wounds, and in patients with cystic fibrosis, we are motivated by the potential for these mechanisms to serve as therapeutic targets.