Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>

ABSTRACT Biofilms formed in the middle ear by nontypeable Haemophilus influenzae (NTHI) are central to the chronicity, recurrence, and refractive nature of otitis media (OM). However, mechanisms that underlie the emergence of specific NTHI biofilm structures are unclear. We combined computational an...

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Autores principales:	Jayajit Das, Elaine Mokrzan, Vinal Lakhani, Lucia Rosas, Joseph A. Jurcisek, William C. Ray, Lauren O. Bakaletz
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	agent-based modeling biofilms nontypeable Haemophilus influenzae otitis media pair correlation Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/269d60c2a31d4aa6abd25f344b89f542
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spelling	oai:doaj.org-article:269d60c2a31d4aa6abd25f344b89f5422021-11-15T15:51:55ZExtracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>10.1128/mBio.01466-172150-7511https://doaj.org/article/269d60c2a31d4aa6abd25f344b89f5422017-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01466-17https://doaj.org/toc/2150-7511ABSTRACT Biofilms formed in the middle ear by nontypeable Haemophilus influenzae (NTHI) are central to the chronicity, recurrence, and refractive nature of otitis media (OM). However, mechanisms that underlie the emergence of specific NTHI biofilm structures are unclear. We combined computational analysis tools and in silico modeling rooted in statistical physics with confocal imaging of NTHI biofilms formed in vitro during static culture in order to identify mechanisms that give rise to distinguishing morphological features. Our analysis of confocal images of biofilms formed by NTHI strain 86-028NP using pair correlations of local bacterial densities within sequential planes parallel to the substrate showed the presence of fractal structures of short length scales (≤10 μm). The in silico modeling revealed that extracellular DNA (eDNA) and type IV pilus (Tfp) expression played important roles in giving rise to the fractal structures and allowed us to predict a substantial reduction of these structures for an isogenic mutant (ΔcomE) that was significantly compromised in its ability to release eDNA into the biofilm matrix and had impaired Tfp function. This prediction was confirmed by analysis of confocal images of in vitro ΔcomE strain biofilms. The fractal structures potentially generate niches for NTHI survival in the hostile middle ear microenvironment by dramatically increasing the contact area of the biofilm with the surrounding environment, facilitating nutrient exchange, and by generating spatial positive feedback to quorum signaling. IMPORTANCE NTHI is a major bacterial pathogen for OM, which is a common ear infection in children worldwide. Chronic OM is associated with bacterial biofilm formation in the middle ear; therefore, knowledge of the mechanisms that underlie NTHI biofilm formation is important for the development of therapeutic strategies for NTHI-associated OM. Our combined approach using confocal imaging of NTHI biofilms formed in vitro and mathematical tools for analysis of pairwise density correlations and agent-based modeling revealed that eDNA and Tfp expression were important factors in the development of fractal structures in NTHI biofilms. These structures may help NTHI survive in hostile environments, such as the middle ear. Our in silico model can be used in combination with laboratory or animal modeling studies to further define the mechanisms that underlie NTHI biofilm development during OM and thereby guide the rational design of, and optimize time and cost for, benchwork and preclinical studies.Jayajit DasElaine MokrzanVinal LakhaniLucia RosasJoseph A. JurcisekWilliam C. RayLauren O. BakaletzAmerican Society for Microbiologyarticleagent-based modelingbiofilmsnontypeable Haemophilus influenzaeotitis mediapair correlationMicrobiologyQR1-502ENmBio, Vol 8, Iss 6 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	agent-based modeling biofilms nontypeable Haemophilus influenzae otitis media pair correlation Microbiology QR1-502
spellingShingle	agent-based modeling biofilms nontypeable Haemophilus influenzae otitis media pair correlation Microbiology QR1-502 Jayajit Das Elaine Mokrzan Vinal Lakhani Lucia Rosas Joseph A. Jurcisek William C. Ray Lauren O. Bakaletz Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>
description	ABSTRACT Biofilms formed in the middle ear by nontypeable Haemophilus influenzae (NTHI) are central to the chronicity, recurrence, and refractive nature of otitis media (OM). However, mechanisms that underlie the emergence of specific NTHI biofilm structures are unclear. We combined computational analysis tools and in silico modeling rooted in statistical physics with confocal imaging of NTHI biofilms formed in vitro during static culture in order to identify mechanisms that give rise to distinguishing morphological features. Our analysis of confocal images of biofilms formed by NTHI strain 86-028NP using pair correlations of local bacterial densities within sequential planes parallel to the substrate showed the presence of fractal structures of short length scales (≤10 μm). The in silico modeling revealed that extracellular DNA (eDNA) and type IV pilus (Tfp) expression played important roles in giving rise to the fractal structures and allowed us to predict a substantial reduction of these structures for an isogenic mutant (ΔcomE) that was significantly compromised in its ability to release eDNA into the biofilm matrix and had impaired Tfp function. This prediction was confirmed by analysis of confocal images of in vitro ΔcomE strain biofilms. The fractal structures potentially generate niches for NTHI survival in the hostile middle ear microenvironment by dramatically increasing the contact area of the biofilm with the surrounding environment, facilitating nutrient exchange, and by generating spatial positive feedback to quorum signaling. IMPORTANCE NTHI is a major bacterial pathogen for OM, which is a common ear infection in children worldwide. Chronic OM is associated with bacterial biofilm formation in the middle ear; therefore, knowledge of the mechanisms that underlie NTHI biofilm formation is important for the development of therapeutic strategies for NTHI-associated OM. Our combined approach using confocal imaging of NTHI biofilms formed in vitro and mathematical tools for analysis of pairwise density correlations and agent-based modeling revealed that eDNA and Tfp expression were important factors in the development of fractal structures in NTHI biofilms. These structures may help NTHI survive in hostile environments, such as the middle ear. Our in silico model can be used in combination with laboratory or animal modeling studies to further define the mechanisms that underlie NTHI biofilm development during OM and thereby guide the rational design of, and optimize time and cost for, benchwork and preclinical studies.
format	article
author	Jayajit Das Elaine Mokrzan Vinal Lakhani Lucia Rosas Joseph A. Jurcisek William C. Ray Lauren O. Bakaletz
author_facet	Jayajit Das Elaine Mokrzan Vinal Lakhani Lucia Rosas Joseph A. Jurcisek William C. Ray Lauren O. Bakaletz
author_sort	Jayajit Das
title	Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>
title_short	Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>
title_full	Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>
title_fullStr	Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>
title_full_unstemmed	Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>
title_sort	extracellular dna and type iv pilus expression regulate the structure and kinetics of biofilm formation by nontypeable <italic toggle="yes">haemophilus influenzae</italic>
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/269d60c2a31d4aa6abd25f344b89f542
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Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable <italic toggle="yes">Haemophilus influenzae</italic>

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