title: Role of the nuclease of nontypeable Haemophilus influenzae in dispersal of organisms from biofilms.
abstract: Nontypeable Haemophilus influenzae (NTHI) forms biofilms in the middle ear during human infection. The biofilm matrix of NTHI contains extracellular DNA. We show that NTHI possesses a potent nuclease, which is a homolog of the thermonuclease of Staphylococcus aureus. Using a biofilm dispersal assay, studies showed a biofilm dispersal pattern in the parent strain, no evidence of dispersal in the nuclease mutant, and a partial return of dispersion in the complemented mutant. Quantitative PCR of mRNA from biofilms from a 24-h continuous flow system demonstrated a significantly increased expression of the nuclease from planktonic organisms compared to those in the biofilm phase of growth (P < 0.042). Microscopic analysis of biofilms grown in vitro showed that in the nuclease mutant the nucleic acid matrix was increased compared to the wild-type and complemented strains. Organisms were typically found in large aggregates, unlike the wild-type and complement biofilms in which the organisms were evenly dispersed throughout the biofilm. At 48 h, the majority of the organisms in the mutant biofilm were dead. The nuclease mutant formed a biofilm in the chinchilla model of otitis media and demonstrated a propensity to also form similar large aggregates of organisms. These studies indicate that NTHI nuclease is involved in biofilm remodeling and organism dispersal.
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Cho
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Aroon
authors.initials: A
authors.lastname: Chande
authors.affiliation: Department of Biochemistry, The University of Iowa, Iowa City, Iowa, USA Protein Crystallography Facility, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Gakhar
authors.affiliation: Center for Microbial Pathogenesis, Nationwide Children's Hospital, Ohio State University, Columbus, Ohio, USA.
authors.forename: Lauren O
authors.initials: LO
authors.lastname: Bakaletz
authors.affiliation: Center for Microbial Pathogenesis, Nationwide Children's Hospital, Ohio State University, Columbus, Ohio, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Jurcisek
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Margaret
authors.initials: M
authors.lastname: Ketterer
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Shao
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Kenji
authors.initials: K
authors.lastname: Gotoh
authors.affiliation: College of Public Health, Department of Biostatistics, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Foster
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Hunt
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: O'Brien
authors.affiliation: Department of Microbiology and Internal Medicine, The University of Iowa, Iowa City, Iowa, USA michael-apicella@uiowa.edu.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Apicella
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D002682:Chinchilla; D004247:DNA / Q000378:metabolism; D003851:Deoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D004432:Ear, Middle / Q000382:microbiology / Q000473:pathology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005110:Extracellular Space / Q000737:chemistry; D015870:Gene Expression; D006193:Haemophilus influenzae / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010033:Otitis Media / Q000382:microbiology / Q000473:pathology; D010933:Plankton / Q000254:growth & development; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013211:Staphylococcus aureus / Q000737:chemistry / Q000201:enzymology
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D004247:DNA; D003851:Deoxyribonucleases