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Role of the nuclease of nontypeable Haemophilus influenzae in dispersal of organisms from biofilms
Journal article   Open access   Peer reviewed

Role of the nuclease of nontypeable Haemophilus influenzae in dispersal of organisms from biofilms

Christine Cho, Aroon Chande, Lokesh Gakhar, Lauren O Bakaletz, Joseph A Jurcisek, Margaret Ketterer, Jian Shao, Kenji Gotoh, Eric Foster, Jason Hunt, …
Infection and immunity, Vol.83(3), pp.950-957
03/2015
DOI: 10.1128/IAI.02601-14
PMCID: PMC4333478
PMID: 25547799
url
https://europepmc.org/articles/pmc4333478View
Published (Version of record) Open Access

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.
Amino Acid Sequence Animals Bacterial Load Bacterial Proteins - genetics Bacterial Proteins - metabolism Biofilms - growth & development Chinchilla Deoxyribonucleases - genetics Deoxyribonucleases - metabolism DNA - metabolism Ear, Middle - microbiology Ear, Middle - pathology Escherichia coli - genetics Escherichia coli - metabolism Extracellular Space - chemistry Gene Expression Haemophilus influenzae - enzymology Haemophilus influenzae - genetics Haemophilus influenzae - growth & development Humans Molecular Sequence Data Mutation Otitis Media - microbiology Otitis Media - pathology Plankton - growth & development Recombinant Proteins - genetics Recombinant Proteins - metabolism Sequence Homology, Amino Acid Staphylococcus aureus - chemistry Staphylococcus aureus - enzymology

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