Currently, there are only two known bacteria capable of synthesizing alginate:
1) P.aeruginosa 2) A.vinelandii.
The two pathways are similar, however:
P.aeruginosa (Bacteria 1)
- produces biofilms that are flexible even upon addition of calcium. For the purposes of this project, a rigid outer capsule will be needed. Therefore, the genes in this pathway cannot be cloned without modification.
- benefit is that P.aeruginosa is well characterised as it is a disease causing organism.
A.vinelandii (Bacteria 2)
- produces a more solid cyst around itself as part of its life cycle.
- is currently being studied for alginate gel poduction in bacteria.
Capsule coat vs. Exopolysaccharides
In the case of gram-negative bacteria, the precise linkage between capsular polysaccharides (CPS) and the outer membrane is not always known, but the processes involved in the biosynthesis and export of CPS and EPS are indistinguishable.