Team:Toulouse/Project/Spreading

From 2014.igem.org

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<p class="title1">Survival in the environment</p>
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<p class="title1">Survival in the environment : proline auxotroph <i>B. subtilis</i></p>
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<p class="texte">SubtiTree will live in sap tree, thus we use one endophyte <I>Bacillus subtilis</I> strain. In order to contain our bacteria in this area during a short period of time, we modified some of its survival characteristics.First of all, the control of synthetic bacterium location concerned us,that is why we border it inside the plane tree. Sap tree is known to contain a certain quantity of proline which could allow bacterial growth whereas the soil is composed by only trace of this amino acid. Thus, we decided to delete the proline production pathway to make an auxotrophic bacterium for this amino acid.  
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<p class="texte">SubtiTree will live in sap tree, thus we use one endophyte <I>Bacillus subtilis</I> strain.In order to contain our bacteria in this area during a short period of time, we modified some of its survival characteristics. To make the bacterium dependant on the tree and to avoid its spreading in the environment, it should be preferable to use a strain of <i>B.subtilis</i> which is auxotroph to a particular amino acid. The bacterium should be unable to synthesize one essential amino acid, and should find it in its environment. The proline could be a good example since it is wide-spread in the phloem sap. It is the amino acid which is present in highest concentration in the phloem sap. If our bacterium is unable to synthesize the proline, it will be obliged to take it in its close environment, that is to say the phloem sap.
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Thus, if the bacterium is in the sap, it can grow normally without any deficiency since it uses the proline present in the sap ; but if it escapes from the tree and <i>a fortiori</i> from the sap, it will not be able to survive for a long time. Indeed, proline is found in low quantities in the ground. This system should guarantee that the bacterium develops only in the tree and not elsewhere in the surroundings of the tree.<br/>
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Auxotroph <i>B.sutbilis</i> strains already exist and are indexed in databases as BGSC (Bacillus Genetic Stock Center), therefore it is easy to find.</p>
<p class="title1">Preventing sporulation of <i>B. subtilis</i></p>
<p class="title1">Preventing sporulation of <i>B. subtilis</i></p>
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<p class="texte">These two first characteristics of SubtiTree show that it is an annual bacterium, which can only grow in sap tree. By combinind them, they prevent any long term colonization of an ecological niche by SubtiTree against wild type bacteria. These prevent a long term effect.</p>
<p class="texte">These two first characteristics of SubtiTree show that it is an annual bacterium, which can only grow in sap tree. By combinind them, they prevent any long term colonization of an ecological niche by SubtiTree against wild type bacteria. These prevent a long term effect.</p>
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<p class="title1">Using a glutamin auxotroph <i>B. subtilis</i> strain</p>
 
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<p class="texte">
 
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To make the bacterium dependant on the tree and to avoid its spreading in the environment, it should be preferable to use a strain of <i>B.subtilis</i> which is auxotroph to a particular amino acid. The bacterium should be unable to synthesize one essential amino acid, and should find it in its environment. The glutamine could be a good example since it is wide-spread in the phloem sap. It is the amino acid which is present in highest concentration in the phloem sap. If our bacterium is unable to synthesize the glutamine, it will be obliged to take it in its close environment, that is to say the phloem sap.
 
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Thus, if the bacterium is in the sap, it can grow normally without any deficiency since it uses the glutamine present in the sap ; but if it escapes from the tree and <i>a fortiori</i> from the sap, it will not be able to survive for a long time. Indeed, glutamine is found in low quantities in the ground. This system should guarantee that the bacterium develops only in the tree and not elsewhere in the surroundings of the tree.<br/>
 
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Auxotroph <i>B.sutbilis</i> strains already exist and are indexed in databases as BGSC (Bacillus Genetic Stock Center), therefore it is easy to find. 
 
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</p>
 
<p class="title1">Using a toxin-antitoxin system</p>
<p class="title1">Using a toxin-antitoxin system</p>

Revision as of 10:18, 13 October 2014