title: Presence of Calcium Lowers the Expansion of Bacillus subtilis Colony Biofilms.
abstract: Robust colony formation byBacillus subtilisis recognized as one of the sessile, multicellular lifestyles of this bacterium. Numerous pathways and genes are responsible for the architecturally complex colony structure development. Cells in the biofilm colony secrete extracellular polysaccharides (EPS) and protein components (TasA and the hydrophobin BslA) that hold them together and provide a protective hydrophobic shield. Cells also secrete surfactin with antimicrobial as well as surface tension reducing properties that aid cells to colonize the solid surface. Depending on the environmental conditions, these secreted components of the colony biofilm can also promote the flagellum-independent surface spreading ofB. subtilis, called sliding. In this study, we emphasize the influence of Ca2+in the medium on colony expansion ofB. subtilis. Interestingly, the availability of Ca2+has no major impact on the induction of complex colony morphology. However, in the absence of this divalent ion, peripheral cells of the colony expand radially at later stages of development, causing colony size to increase. We demonstrate that the secreted extracellular compounds, EPS, BslA, and surfactin facilitate colony expansion after biofilm maturation. We propose that Ca2+hinders biofilm colony expansion by modifying the amphiphilic properties of surfactin.
authors.affiliation: Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena 07743, Germany. eisha.r.mhatre@gmail.com.
authors.forename: Eisha
authors.initials: E
authors.lastname: Mhatre
authors.affiliation: Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena 07743, Germany. sundar.sabitha@gmail.com.
authors.forename: Anandaroopan
authors.initials: A
authors.lastname: Sundaram
authors.affiliation: Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena 07743, Germany. thoelscher@ice.mpg.de.
authors.forename: Theresa
authors.initials: T
authors.lastname: Hölscher
authors.affiliation: Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Jena 07743, Germany. mike.muehlstaedt@uni-jena.de.
authors.forename: Mike
authors.initials: M
authors.lastname: Mühlstädt
authors.affiliation: Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Jena 07743, Germany. Joerg.Bossert@uni-jena.de.
authors.forename: Jörg
authors.initials: J
authors.lastname: Bossert
authors.affiliation: Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena 07743, Germany. akos-tibor.kovacs@uni-jena.de.
authors.forename: Ákos T
authors.initials: ÁT
authors.lastname: Kovács
keywords: Bacillus subtilis; biofilm; calcium; colony expansion; sliding; surfactin