Team:Toulouse/Project/Spreading

From 2014.igem.org

(Difference between revisions)
Line 94: Line 94:
<p class="title1">Survival in the environment : proline auxotroph <i>B. subtilis</i></p>
<p class="title1">Survival in the environment : proline auxotroph <i>B. subtilis</i></p>
-
<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.  
+
<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.  
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/>  
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/>  
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>
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>
Line 114: Line 114:
<br>Considering this issue, we thought about a system to avoid such transfers : a toxin-antitoxin module. It involves the addition of two genes to the bacterium : a gene encoding for a toxin (for example <i>tse2</i>) and a gene encoding for the antitoxin (<i>tsi1</i>), placing them in an opposite way on the genome. The large space between them prevents simultaneous transfers : if the optimised bacterium transfers the gene encoding for the toxin, the probability that the gene encoding for the antitoxin may be transferred simultaneously is really low since they are located far away from each other.<br/>
<br>Considering this issue, we thought about a system to avoid such transfers : a toxin-antitoxin module. It involves the addition of two genes to the bacterium : a gene encoding for a toxin (for example <i>tse2</i>) and a gene encoding for the antitoxin (<i>tsi1</i>), placing them in an opposite way on the genome. The large space between them prevents simultaneous transfers : if the optimised bacterium transfers the gene encoding for the toxin, the probability that the gene encoding for the antitoxin may be transferred simultaneously is really low since they are located far away from each other.<br/>
Therefore, if the host bacterium receives the gene encoding for the toxin, it will be unable to survive since it will not have the antitoxin. If it receives the antitoxin only, it will not be useful for the bacterium, and will not affect it.<br/>
Therefore, if the host bacterium receives the gene encoding for the toxin, it will be unable to survive since it will not have the antitoxin. If it receives the antitoxin only, it will not be useful for the bacterium, and will not affect it.<br/>
-
To sum up, since a simultaneous transfer is dimly probable, the bacterium will either die because of the toxin or live while expressing the antitoxin (useless).  
+
To sum up, since a simultaneous transfer is dimly probable, the bacterium will either die because of the toxin or live while expressing the antitoxin.  
</p>
</p>

Revision as of 11:24, 13 October 2014