Transcript Biofilms

Utilisation of bacteria for
anti-fouling biofilm able to
avoid the settlement and
growth of micro&macro
organisms
Fouling mechanism
• 1: adherence of
bact. Colony (Van
der Waals)
• 2: anchoring (pilis)
• 3: polysaccharide
matrix
• 4: M.O. Attachment
• 5: More fouling
State of research...
• Study of inhibitory effect of various bact.
strains on various M.O.
• Characterization of attachment
mechanism of fouling agents
• Characterization of inhibiting extracellular
products
Advantages/drawbacks
+
Up to 90 % inhibition of
MO
No toxic paint on hulls
Many different MO types
→ effect limited to spec.
species
Mutations: cancel inhib.
effect
Feasibility
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Genetically: ?
Sea: very complex medium
Need significant upstream research
(surface materials, )
Need experimental validation of
designed bacteria with many different
conditions → more time than actual
engineering ?
Lots of economical interest in this
Bacteria used
• Alteromonas
• Pseudoalteromonas : extensively studied
for its anti-fouling activity
=> Inhibit the settlement and growth of a
large number of organisms
Anti-fouling substance produced
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Protein or peptide
Thermostable
Hydrophilic
>3500 daltons in molecular size
 Inhibition of settlement by 2 ways:
- direct: induce lysis in cultures
- Indirect: emission from the bacteria of chemical
products which inhibit growth and settlement
Two possibilities
1. Continuous secretion of a given molecule
which will avoid the deposit of molluscs
on the hull
1. Secretion in response to a given input
(e.g. shear stress)
Description of the bioparts
1. Input: when bacteria sense an external
input, triggering of the production of a
certain molecule to avoid the deposit of
plants and mollusc, for example in
response to pressure
=> possibility to use luxR for example for
the modelisation = inducible promoter,
normally off, which turn on in response to
an external input
Description of the bioparts
2. Output: the bacteria can produce a
molecule in order to kill molluscs attached or
to prevent the adhesion.
=> possibility to use something like GFP as
an output in our modelisation
Description of the bioparts
• 3. Filter: need to avoid the noise
coherent feedforward loop with AND-gate.
Input  fast degrading primary messenger
 stable secondary messenger  ANDgate