Kinetics of growth and product formation during fermentation (bacterion biosynthesis) and bioconversion (enzymatic conversion of cis-epoxysuccinate to L(+)-tartaric acid) processes in filtration culture.

For efficient cell-related product formation via fermentation or bioconversion, a high cell yield is necessary, a high productivity must be achieved, it is desirable to work continuously, to keep a long-term stability, and to easily performthe downstream processing. By means of a filtration culture, this is a fermenter or bioreactor coupled to a filtrationmodule (for instance a hollow fibre module), equipped with membranes of an appropriate molecular mass cut off,problems such as a too low cell yield, substrate and/or product inhibition, etc. can be avoided. In a membranerecirculation reactor the cells are recycled via the membrane module, and returned to the reactor; part of the medium(inhibitory or toxic end products included) is withdrawn via the membranes.Two model systems will be studied. On the one hand a fermentation process, namely the biosynthesis of thebacteriocin amylovorin L471 produced by Lactobacillus amylovorus DCE 471, and a bioconversion process, namelythe enzymatic conversion of ci~epoxysuccinate to L(+) tartaric acid with Rhodococcus rhodochrous cells. Filtrationculture will allow to prolong the active growth phase, to improve the cell yield and to perform product formation athigh cell densities.