Laser Desorption Postionization Mass Spectrometric Analysis of Multispecies Coculture Biofilms

Microorganisms often exist as complex functional communities known as biofilms. These communities usually comprise of multiple interacting species including bacteria and fungi. Controlling these multi species biofilms is a challenge due to the heterogeneity and spatial localization of microbial structure and interaction within them. Structural and functional understanding of these multi microbe biofilms is of significance to the environmental, medical and industrial settings in which they appear. The present thesis work utilized laser desorption postionization mass spectrometry (LDPI-MS) to study two genetically modified model biofilm systems of interacting microbes. These models were chosen to mimic naturally occurring binary consortia utilizing syntrophic exchange of metabolites. LDPI-MS was demonstrated to detect endogenous species from spatially resolved locations within intact coculture biofilms. The effect of photoionization energy on the detection of these endogenous compounds was examined using a fluorine excimer laser and a vacuum ultraviolet source built for this study. Multivariate analysis was also applied to the LDPI-MS data from coculture biofilms of closely related bacterial strains. The studies demonstrated differentiation of spatially localized regions in coculture biofilms based on metabolic profile of participating species.