QseC controls biofilm formation of non-typeable Haemophilus influenzae in addition to an AI-2-dependent mechanism

Int J Med Microbiol. 2012 Nov;302(6):261-9. doi: 10.1016/j.ijmm.2012.07.013. Epub 2012 Sep 4.


Non-typeable Haemophilus influenzae (NTHi) is a common pathogen associated with diseases such as acute otitis media or exacerbations in patients with chronic obstructive pulmonary disease. The biofilm-forming capability substantially contributes to the persistence of NTHi. However, the regulation of biofilm formation is not completely understood. Quorum sensing regulated by autoinducer-2 produced by luxS is until now the only described regulatory mechanism. In this study, we show that the two-component signalling system QseB/C is involved in the biofilm formation of NTHi in vitro. An isogenic NTHi mutant of qseC (Hi3655KR2) showed a significant decrease in biofilm formation under static and semi-static conditions as assessed by crystal violet staining. In addition, under constant flow conditions, Hi3655KR2 formed less biofilm after 48 h. The biofilm defects were irrespective of autoinducer-2 levels. Hence, here we suggest for the first time a regulatory circuit in NTHi, which controls biofilm formation by mechanisms other than or in addition to luxS-dependent factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biofilms*
  • Carbon-Sulfur Lyases / genetics
  • Carbon-Sulfur Lyases / metabolism
  • Culture Media / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / physiology
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Gene Expression Regulation, Bacterial
  • Gene Knockout Techniques
  • Genes, Bacterial
  • Genetic Complementation Test
  • Gentian Violet
  • Haemophilus influenzae / genetics
  • Haemophilus influenzae / physiology*
  • Homologous Recombination
  • Homoserine / analogs & derivatives*
  • Homoserine / metabolism
  • Lactones / metabolism*
  • Luminescent Measurements
  • Microbial Viability
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Quorum Sensing*
  • Sequence Homology, Amino Acid
  • Time Factors


  • Bacterial Proteins
  • Culture Media
  • Escherichia coli Proteins
  • Lactones
  • N-octanoylhomoserine lactone
  • QseC protein, E coli
  • Homoserine
  • Carbon-Sulfur Lyases
  • LuxS protein, Bacteria
  • Gentian Violet