abacterial extracellular dna inhibits settling of motile...
TRANSCRIPT
A bacterial extracellular DNA inhibits settling of motile progeny
cells within a biofilm
Cecile Berne, David T. Kysela and Yves V. BrunMolecular Microbiology (2010) 77(4), 815‐829
Speaker: Fang‐Yi ChuAdvisor: Ching‐Tsan Huang, Ph.D.
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Biofilm• An aggregate of microorganisms• Attachment on a surface
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Impact of biofilm
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Biofilm resistance
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Resistance gene
Biofilm formation• Biofilms : extracellular matrix (great resistance)• Detachment• Dispersal: deterioration of habitat
‐ planktonic phase
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Extracellular DNA• eDNA stabilized biofilm
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Tetz et al, DNA AND CELL BIOLOGY (2010)
Listeria monocytogenes
Harmwen et al, APPLIED AND ENVIRONMENTAL MICROBIOLOGY, (2010)
Caulobacter crescentus• An innocuous oligotrophic ‐proteobacterium• colonizes streams, rivers, and water pipes • strongest adhesion force of any known natural material
‐‐PNAS (2006) 103: 5764‐5768 • biodegradable surgical adhesive
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Swarmer cell
Stalked cell
holdfast
Motile swarmer cell and stalked cell
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Electron micrograph of Caulobacter crescentus
Rationale
• The role of eDNA within C. cresentus biofilm• The balance between biofilm and dispersal
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In this paper….
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Structure
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How does the eDNA work?
Where does the eDNA come from?
What role does eDNA play in C.crescentus?
DNase I recovered the inhibition of biofilm formation.
12→eDNA inhibited biofilm formation.
The eDNA in the spent medium
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M eDNA M
Lower molecular weight DNA fragments inhibited biofilmformation.
∆ digested genomic DNAО eDNA
spend medium
Addition of digested gDNAhad the same inhibition as spend medium.
500 bp
Structure
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How does the eDNA work?
Where does the eDNA come from?
What role does eDNA play in C.crescentus?
Correlation between cell death, eDNArelease and biofilm inhibition
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eDNA was released during cell death.
Structure
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How does the eDNA work?
Where does the eDNA come from?
What role does eDNA play in C.crescentus?
The inhibition in pili and flagellum mutant
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70% decreaseBlank: no gDNA/eDNABlack: digested gDNA (wt)Stripe: digested gDNA (∆pulA)Dot: digested gDNA (∆flgE)
The biofilm inhibition was not due to interaction between eDNAand pili or eDNA and flagellum.
Later attachment with eDNA
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w/ eDNA
w/o eDNA
Holdfast‐deficient
eDNA prevented the attachment of swimming cells by holdfast.
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Colocalization of eDNA and holdfast
eDNA inhibited biofilm formation by binding to holdfast.
Summary
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Discussion (I)
21Whitchurch et al, Science (2002)
Pseudomonas aeruginosa Staphylococcus epidermidis
Qin, et al, Microbiology (2007)
The addition of DNase I inhibited biofilm formation and dissolved established biofilm.
Previous studies: eDNA stabilized biofilm formation
The addition of Dnase I
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Biofilm formation within DNase I (red)
Effect of DNase I (red) on established biofilms.
Dnase I did not inhibit biofilm formation and dissolve established biofilms. Therefore, eDNA did not stabilize biofilm of C. crescentus.
Discussion (II)
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Harmwen et al, APPLIED AND ENVIRONMENTAL MICROBIOLOGY, (2010)
Grande et al, Applied Microbiology (2010)
eDNA stabilized biofilm in previous studies: 20~30KbeDNA inhibited biofilm formation in this paper: 500bp
M eDNA M
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high‐molecular‐weight DNA (20~30Kb): stabilitylow‐molecular‐weight DNA (500bp): inhibition
Listeria monocytogenes.
Dnase I
Digested gDNA
gDNA by PCR
The size of eDNA is probably a key factor of decision between stability and inhibition.
Harmwen et al, APPLIED AND ENVIRONMENTAL MICROBIOLOGY, (2010)
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eDNA
Caulobacter crescentus
M eDNA M
Thanks for your attention!
Special thanks for Professor Ching‐TsanHuang
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