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Extracellular DNA is essential for maintaining Bordetella biofilm integrity on abiotic surfaces and in the upper respiratory tract of mice.

Conover MS, Mishra M, Deora R - PLoS ONE (2011)

Bottom Line: We show that DNA is a significant component of Bordetella biofilm matrix.In conclusion, these results suggest that eDNA is a crucial structural matrix component of both in vitro and in vivo formed Bordetella biofilms.This is the first evidence for the ability of DNase I to disrupt bacterial biofilms formed on host organs.

View Article: PubMed Central - PubMed

Affiliation: Program in Molecular Genetics, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America.

ABSTRACT
Bacteria form complex and highly elaborate surface adherent communities known as biofilms which are held together by a self-produced extracellular matrix. We have previously shown that by adopting a biofilm mode of existence in vivo, the gram negative bacterial pathogens Bordetella bronchiseptica and Bordetella pertussis are able to efficiently colonize and persist in the mammalian respiratory tract. In general, the bacterial biofilm matrix includes polysaccharides, proteins and extracellular DNA (eDNA). In this report, we investigated the function of DNA in Bordetella biofilm development. We show that DNA is a significant component of Bordetella biofilm matrix. Addition of DNase I at the initiation of biofilm growth inhibited biofilm formation. Treatment of pre-established mature biofilms formed under both static and flow conditions with DNase I led to a disruption of the biofilm biomass. We next investigated whether eDNA played a role in biofilms formed in the mouse respiratory tract. DNase I treatment of nasal biofilms caused considerable dissolution of the biofilm biomass. In conclusion, these results suggest that eDNA is a crucial structural matrix component of both in vitro and in vivo formed Bordetella biofilms. This is the first evidence for the ability of DNase I to disrupt bacterial biofilms formed on host organs.

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Related in: MedlinePlus

Susceptibility of flow cell biofilms to DNase I.Representative z-reconstructions of RB50 biofilms grown under flow conditions for 6, 72, or 120h and imaged using CLSM for live GFP expressing cells (green) and eDNA stained with DDAO (red or yellow with co-localization). The image of untreated biofilms (left panels) were taken immediately prior to incubation with DNase I and the images of same biofilms treated with DNase I for 1.5h (left panels). Images shown here are representative of two independent experiments.
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pone-0016861-g005: Susceptibility of flow cell biofilms to DNase I.Representative z-reconstructions of RB50 biofilms grown under flow conditions for 6, 72, or 120h and imaged using CLSM for live GFP expressing cells (green) and eDNA stained with DDAO (red or yellow with co-localization). The image of untreated biofilms (left panels) were taken immediately prior to incubation with DNase I and the images of same biofilms treated with DNase I for 1.5h (left panels). Images shown here are representative of two independent experiments.

Mentions: At the early time point of biofilm formation, bacteria existed mainly in diffuse thin patches with large areas of coverslips remaining free of bacterial cells. At this time point, we were unable to detect significant levels of DNA (Fig. 5). At 72h, the biofilm increased in thickness and density with the emergence of some structural features in the form of thin closely clustered spikes or pillars. At this stage of biofilm formation, DNA was present in low but detectable levels. Dramatically at 120h of growth, the bacterial cells displayed attributes of highly structured biofilms with appearance of thick dome shaped pillar structures and water channels. Staining with DDAO revealed that this biofilm contained large amounts of DNA as indicated by yellow staining (Fig. 5). Unlike that observed with other bacteria, DNA did not appear to be localized at specific regions of the dome shaped biofilm structure [34], [36]. Instead DNA was found to be distributed throughout the biofilm. Note that these images are Z-reconstructions of multiple frames of the biofilms formed in the flow cell. Due to the compression and overlay of multiple images, colocalization of the red and green stains will occur. Thus, the yellow staining is indicative of eDNA closely associated with the GFP expressing bacteria.


Extracellular DNA is essential for maintaining Bordetella biofilm integrity on abiotic surfaces and in the upper respiratory tract of mice.

Conover MS, Mishra M, Deora R - PLoS ONE (2011)

Susceptibility of flow cell biofilms to DNase I.Representative z-reconstructions of RB50 biofilms grown under flow conditions for 6, 72, or 120h and imaged using CLSM for live GFP expressing cells (green) and eDNA stained with DDAO (red or yellow with co-localization). The image of untreated biofilms (left panels) were taken immediately prior to incubation with DNase I and the images of same biofilms treated with DNase I for 1.5h (left panels). Images shown here are representative of two independent experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037945&req=5

pone-0016861-g005: Susceptibility of flow cell biofilms to DNase I.Representative z-reconstructions of RB50 biofilms grown under flow conditions for 6, 72, or 120h and imaged using CLSM for live GFP expressing cells (green) and eDNA stained with DDAO (red or yellow with co-localization). The image of untreated biofilms (left panels) were taken immediately prior to incubation with DNase I and the images of same biofilms treated with DNase I for 1.5h (left panels). Images shown here are representative of two independent experiments.
Mentions: At the early time point of biofilm formation, bacteria existed mainly in diffuse thin patches with large areas of coverslips remaining free of bacterial cells. At this time point, we were unable to detect significant levels of DNA (Fig. 5). At 72h, the biofilm increased in thickness and density with the emergence of some structural features in the form of thin closely clustered spikes or pillars. At this stage of biofilm formation, DNA was present in low but detectable levels. Dramatically at 120h of growth, the bacterial cells displayed attributes of highly structured biofilms with appearance of thick dome shaped pillar structures and water channels. Staining with DDAO revealed that this biofilm contained large amounts of DNA as indicated by yellow staining (Fig. 5). Unlike that observed with other bacteria, DNA did not appear to be localized at specific regions of the dome shaped biofilm structure [34], [36]. Instead DNA was found to be distributed throughout the biofilm. Note that these images are Z-reconstructions of multiple frames of the biofilms formed in the flow cell. Due to the compression and overlay of multiple images, colocalization of the red and green stains will occur. Thus, the yellow staining is indicative of eDNA closely associated with the GFP expressing bacteria.

Bottom Line: We show that DNA is a significant component of Bordetella biofilm matrix.In conclusion, these results suggest that eDNA is a crucial structural matrix component of both in vitro and in vivo formed Bordetella biofilms.This is the first evidence for the ability of DNase I to disrupt bacterial biofilms formed on host organs.

View Article: PubMed Central - PubMed

Affiliation: Program in Molecular Genetics, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America.

ABSTRACT
Bacteria form complex and highly elaborate surface adherent communities known as biofilms which are held together by a self-produced extracellular matrix. We have previously shown that by adopting a biofilm mode of existence in vivo, the gram negative bacterial pathogens Bordetella bronchiseptica and Bordetella pertussis are able to efficiently colonize and persist in the mammalian respiratory tract. In general, the bacterial biofilm matrix includes polysaccharides, proteins and extracellular DNA (eDNA). In this report, we investigated the function of DNA in Bordetella biofilm development. We show that DNA is a significant component of Bordetella biofilm matrix. Addition of DNase I at the initiation of biofilm growth inhibited biofilm formation. Treatment of pre-established mature biofilms formed under both static and flow conditions with DNase I led to a disruption of the biofilm biomass. We next investigated whether eDNA played a role in biofilms formed in the mouse respiratory tract. DNase I treatment of nasal biofilms caused considerable dissolution of the biofilm biomass. In conclusion, these results suggest that eDNA is a crucial structural matrix component of both in vitro and in vivo formed Bordetella biofilms. This is the first evidence for the ability of DNase I to disrupt bacterial biofilms formed on host organs.

Show MeSH
Related in: MedlinePlus