title: A dual role of extracellular DNA during biofilm formation of Neisseria meningitidis.
abstract: Major pathogenic clonal complexes (cc) of Neisseria meningitidis differ substantially in their point prevalence among healthy carriers. We show that frequently carried pathogenic cc (e.g. sequence type ST-41/44 cc and ST-32 cc) depend on extracellular DNA (eDNA) to initiate in vitro biofilm formation, whereas biofilm formation of cc with low point prevalence (ST-8 cc and ST-11 cc) was eDNA-independent. For initial biofilm formation, a ST-32 cc type strain, but not a ST-11 type strain, utilized eDNA. The release of eDNA was mediated by lytic transglycosylase and cytoplasmic N-acetylmuramyl-L-alanine amidase genes. In late biofilms, outer membrane phospholipase A-dependent autolysis, which was observed in most cc, but not in ST-8 and ST-11 strains, was required for shear force resistance of microcolonies. Taken together, N. meningitidis evolved two different biofilm formation strategies, an eDNA-dependent one yielding shear force resistant microcolonies, and an eDNA-independent one. Based on the experimental findings and previous epidemiological observations, we hypothesize that most meningococcal cc display a settler phenotype, which is eDNA-dependent and results in a stable interaction with the host. On the contrary, spreaders (ST-11 and ST-8 cc) are unable to use eDNA for biofilm formation and might compensate for poor colonization properties by high transmission rates.
authors.affiliation: University of Würzburg, Institute for Hygiene and Microbiology, Germany. mlappann@hygiene.uni-wuerzburg.de
authors.forename: Martin
authors.initials: M
authors.lastname: Lappann
authors.forename: Heike
authors.initials: H
authors.lastname: Claus
authors.forename: Tessa
authors.initials: T
authors.lastname: van Alen
authors.forename: Morten
authors.initials: M
authors.lastname: Harmsen
authors.forename: Johannes
authors.initials: J
authors.lastname: Elias
authors.forename: Søren
authors.initials: S
authors.lastname: Molin
authors.forename: Ulrich
authors.initials: U
authors.lastname: Vogel
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001433:Bacteriolysis; D018441:Biofilms / Q000254:growth & development*; D004269:DNA, Bacterial / Q000378:metabolism*; D016695:Glycosyltransferases / Q000378:metabolism; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000378:metabolism; D009345:Neisseria meningitidis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D010740:Phospholipases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D016695:Glycosyltransferases; D010740:Phospholipases; D009238:N-Acetylmuramoyl-L-alanine Amidase