title: Characterization of Bacillus subtilis Colony Biofilms via Mass Spectrometry and Fluorescence Imaging.
abstract: Colony biofilms of Bacillus subtilis are a widely used model for studying cellular differentiation. Here, we applied matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) to examine cellular and molecular heterogeneity in B. subtilis colony biofilms. From B. subtilis cells cultivated on a biofilm-promoting medium, we detected two cannibalistic factors not found in previous MALDI MSI studies of the same strain under different culturing conditions. Given the importance of cannibalism in matrix formation of B. subtilis biofilms, we employed a transcriptional reporter to monitor matrix-producing cell subpopulations using fluorescence imaging. These two complementary imaging approaches were used to characterize three B. subtilis strains, the wild type isolate NCIB3610, and two mutants, Δspo0A and ΔabrB, with defective and enhanced biofilm phenotypes, respectively. Upon deletion of key transcriptional factors, correlated changes were observed in biofilm morphology, signaling, cannibalistic factor distribution, and matrix-related gene expression, providing new insights on cannibalism in biofilm development. This work underscores the advantages of using multimodal imaging to compare spatial patterns of selected molecules with the associated protein expression patterns, obtaining information on cellular heterogeneity and function not obtainable when using a single method to characterize biofilm formation.
authors.affiliation: Department of Chemical and Biomolecular Engineering and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Tong
authors.initials: T
authors.lastname: Si
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Yiran
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Chemical and Biomolecular Engineering and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Department of Bioengineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Department of Bioengineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Jonathan V
authors.initials: JV
authors.lastname: Sweedler
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry* / Q000166:cytology / Q000235:genetics; D018441:Biofilms; D057899:Cytophagocytosis / Q000235:genetics; D009154:Mutation; D061848:Optical Imaging; D010641:Phenotype; D040901:Proteomics / Q000379:methods; D059010:Single-Cell Analysis / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D014157:Transcription Factors / Q000032:analysis
chemical_list: D014157:Transcription Factors
keywords: biofilm; cell differentiation; fluorescence imaging; mass spectrometry imaging; transcriptional reporter