title: The prevalence and origin of exoprotease-producing cells in the Bacillus subtilis biofilm.
abstract: Biofilm formation by the Gram-positive bacterium Bacillus subtilis is tightly controlled at the level of transcription. The biofilm contains specialized cell types that arise from controlled differentiation of the resident isogenic bacteria. DegU is a response regulator that controls several social behaviours exhibited by B. subtilis including swarming motility, biofilm formation and extracellular protease (exoprotease) production. Here, for the first time, we examine the prevalence and origin of exoprotease-producing cells within the biofilm. This was accomplished using single-cell analysis techniques including flow cytometry and fluorescence microscopy. We established that the number of exoprotease-producing cells increases as the biofilm matures. This is reflected by both an increase at the level of transcription and an increase in exoprotease activity over time. We go on to demonstrate that exoprotease-producing cells arise from more than one cell type, namely matrix-producing and non-matrix-producing cells. In toto these findings allow us to add exoprotease-producing cells to the list of specialized cell types that are derived during B. subtilis biofilm formation and furthermore the data highlight the plasticity in the origin of differentiated cells.
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Marlow
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: Francesca R
authors.initials: FR
authors.lastname: Cianfanelli
authors.affiliation: Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Porter
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: Lynne S
authors.initials: LS
authors.lastname: Cairns
authors.affiliation: Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: J Kim
authors.initials: JK
authors.lastname: Dale
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: Nicola R
authors.initials: NR
authors.lastname: Stanley-Wall
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D020689:Exopeptidases / Q000378:metabolism*; D005434:Flow Cytometry; D008856:Microscopy, Fluorescence
chemical_list: D020689:Exopeptidases