AVS 60th International Symposium and Exhibition
    Applied Surface Science Wednesday Sessions
       Session AS+BI+IS-WeM

Paper AS+BI+IS-WeM12
Differentiation of Microbial Species & Strains in Coculture Biofilms by Multivariate Analysis of Laser Desorption Postionization Mass Spectra

Wednesday, October 30, 2013, 11:40 am, Room 204

Session: Ambient Ionization Mass Spectrometry
Presenter: L. Hanley, University of Illinois at Chicago
Authors: C. Bhardwaj, University of Illinois at Chicago
Y. Cui, University of Illinois at Chicago
H.C. Bernstein, Montana State University
R.P. Carlson, Montana State University
L. Hanley, University of Illinois at Chicago
Correspondent: Click to Email
The metabolic states of microbial biofilms vary with growth conditions such as host surface, culture media, or antibiotic concentration. 7.87 and 10.5 eV vacuum ultraviolet (VUV) photon energies were used in laser desorption postionization mass spectrometry (LDPI-MS) to analyze microbial biofilms comprised of binary cultures of interacting microorganisms grown on polymer membranes. Principal components analysis (PCA) was applied to the MS data to differentiate species in Escherichia coli-Saccharomyces cerevisiae coculture biofilms. PCA of LDPI-MS also differentiated individual E. coli strains in a biofilm comprised of two interacting gene deletion strains, even though these strains differed from the wild type K-12 strain by no more than four gene deletions each out of approximately 2000 genes. PCA treatment of 7.87 eV LDPI-MS data separated the E. coli strains into two “pure” groups and a distinct mixed region. Furthermore, the “pure” regions of the E. coli cocultures showed greater variance by PCA when analyzed by 7.87 eV photon energies than by 10.5 eV radiation. Comparison of the 7.87 and 10.5 eV data is consistent with the expectation that the lower photon energy selects a subset of low ionization energy analytes while 10.5 eV is more inclusive, detecting a wider range of analytes. These two VUV photon energies therefore give different spreads via PCA and their respective use in LDPI-MS constitute an additional experimental parameter to differentiate the metabolite states of microbial biofilms growing on different surfaces.