Difference between revisions of "Part:BBa K802000"

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	The 3D constructions are obtained with IMARIS software.</p>		The 3D constructions are obtained with IMARIS software.</p>
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Revision as of 20:22, 21 September 2012

Lysostaphin generator for B. subtilis

This part associates the Bacillus subtillis Constitutive Promoter (PVeg) with the lysostaphin gene. Lysostaphin is a bacterial biocide isolated from Staphylococcus simulans and which specifically cleaves the pentaglycine cross bridges found in the staphylococcal peptidoglycan. It contains the necessary RBS to work. With this part, Bacillus subtillis strains cause the lysis of Staphylococcus aureus cells.

Characterization

Following results show that this part enables to B. subtillis 168 strains to kill the S. aureus and epidermidis cells.

In our plasmid collection, this part is named pBK23 in the backbone Chloramphenicol and pBK28 in the shuttle vector E. coli – B. subtillis (Part BBa_K802003). The corresponding negative control is the shuttle vector (pBK25 in our collection). We worked with the plasmid pBK28 for the tests and we tried two different genetic backgrounds: the strain NM522 to make test in E. coli and the strain Bs 168 to make test in Bacillus subtillis.

In you have any question on the following experiments, don’t forget that all the informations relative to our strains, plasmids and protocols are on our wiki notebook.

Confocal Microscopy

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Biofilms are formed by the S. aureus fluorescent strain RN4220 pALC2084 expressing GFP. It is a nonmotile laboratory strain, used to form biofilm in 96-well microscopic-grade microtiter plate.

Bacillus subtillis 168 transformed by pBK28 (lysostaphin in the shuttle vector) and by pBK25 (the shuttle vector without gene to have a negative control) were grown on LB medium supplemented with erythromycin (15µg/mL).
After 24h of culture at 30°C without shaking, biofilm were observed under a time-lapse confocal microscope.
Cells expressing GFP were excited at 488 nm with an argon laser, and fluorescent emission was collected on a detector in the range of 500-600 nm using an oil-immersion objective with a magnification of 63x. The overall three-dimensional structures of the biofilms were scanned from the solid surface to the interface with the growth medium, using a step of 1 µm.
The 3D constructions are obtained with IMARIS software.

S.aureus biofilm no treated (Blank)

S.aureus biofilm treats by the strain with the part

SDS-PAGE Protein gel

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OD(600nm) Test

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Usage and Biology

This part was designed to be used in a motile strain like Bacillus subtillis 168 or Bacillus thuringiensis in order to cause the lysis of the Staphilococcus aureus cells. The motility of the strain make easier his penetration inside the biofilm.

Sequence and Features