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Team:Evry/Biology/Chassis/Motivation
From 2014.igem.org
A specific chassis for specific environments: Seas & Oceans
== A duo from the sea ==
As seen in the overview our biosensors should work optimally in native marine conditions (approximately 24-30 g/L NaCl). Moreover it has to attach to sponges and stick with them without disturbing the microbiome for as long as possible. Therefore it is necessary to use a bacterium naturally present on sponges, may it be an epibiont or a symbiont.
Unfortunately it is a condition for which no current chassis in iGEM is ready for. It is still worth noticing that an interesting first effort toward a marine chassis was initiated by UCL 2012.
To be up to the task the bacterium should:
- be massively present on the sponge surface / avoiding being in an unfavourable position for food competition.
- be found mainly in sponges / avoid spreading to species in contact with sponges.
- be the phenotypically closest possible to a known bacterium / avoid cell cultures difficulties.
To be up to the task the sponge should:
- be numerously present in the ocean / avoiding putting species in danger.
- be a natural host of the bacterium / avoid adapting its microbiome to the new epibiont.
- be easily grown in a laboratory / avoid sponge culture difficulties.
The closest combination sponge/bacterium that could fit these requirements is Spongia Officinalis / Pseudovibrio denitrificans
== Born to filter: Spongia officinalis ==
Spongia officinalis has been used for millennia and for various purposes: from the Greeks for bathing and lining their armours, to today's pharmaceutical attempts to produce anticonvulsant and other therapeutics, not even mentioning the use by Arabic physicians as early as 932 A.D of soaked sponges with narcotic drugs to place over the patient’s nose to provide a state of anesthesia. In a nutshell everyone knows the "bath sponge".
Spongia officinalis is a leuconoid sponge. A leuconoid sponge has a thick body wall, and the ostia open into incurrent canals that draw water into the sponge’s body. These incurrent canals open into chambers that are lined with choanocytes. Water flows from these chambers into excurrent canals that empty into a relatively small spongocoel. From there, water exits through an osculum.
Unlike asconoid and syconoid sponges, which are basically built around their spongocoels and oscula, a leuconoid sponge has a complex, irregularly-shaped body that may have several oscula. It allows a leuconoid sponge to grow to larger size.
It also provides them with powerful filtration capacity (approximately 1200 times its volume per day) which makes it a perfect host for our system. But as mentioned earlier our aim is to engineer an epibiont and not the sponge itself.
Following this introduction, we will both describe what Pseudovibrio denitrificans exactly is and how we turned it into a transformable/selectable-ready chassis.
