Abstract

Correlated Chemical Imaging and Spatiotemporal Organization in Microbial Communities

Paul Bohn, Arthur J. Schmitt Professor of Chemical and Biomolecular Engineering and Professor of Chemistry and Biochemistry, University of Notre Dame

Biofilms, such as those formed by the opportunistic human pathogen Pseudomonas aeruginosa are complex, matrix-enclosed, surface-associated communities of cells that exhibit properties - such as enhanced resistance to antibiotics - distinct from their free-floating counterparts. P. aeruginosa biofilms are associated with persistent and chronic infections in diseases such as cystic fibrosis and HIV-AIDS and thus are primary targets for the lab-on-a-chip community. P. aeruginosa cells organize themselves by synthesizing and secreting signaling molecules, implicated in quorum sensing (QS), and in regulating biofilm formation and virulence. Correlated chemical imaging using powerful molecular imaging platforms, such as confocal Raman microscopy and SIMS-based mass spectrometric imaging, in conjunction with multivariate statistical tools, are being applied to study the spatial and temporal distributions of signaling molecules, secondary metabolites and virulence factors in biofilm communities of P. aeruginosa. These studies reveal that laboratory strains of Pseudomonas differ significantly both from genetic mutants and from clinical isolate strains in the mechanisms used for chemical communication as well as the organization of the resulting biofilms in monoculture.  They also reveal significant modes of action in co-cultures involving different strains and different bacterial species.