  This work is related to the setup of overflowing exponential fed-batch
cultures (O-EFBC) derived from carbon limited EFBC dedicated to the production
of mycosubtilin, an antifungal lipopeptide belonging to the iturin family.
O-EFBC permits the continuous removal of the product from the bioreactor
achieving a complete extraction of mycosubtilin. This paper also provides a
dynamical Monod-based growth model of this process that is accurate enough to
simulate the evolution of the specific growth rate and to correlate it to the
mycosubtilin specific productivity. Two particular and dependant phenomena
related to the foam overflow are taken into account by the model: the outgoing
flow rate of a broth volume and the loss of biomass. Interestingly, the biomass
concentration in the foam was found to be lower than the biomass concentration
in the bioreactor relating this process to a recycling one. Parameters of this
model are the growth yield on substrate and the maximal specific growth rate
estimated from experiments led at feed rates of 0.062, 0.071 and 0.086 h --1.
The model was extrapolated to five additional experiments carried out at feed
rates of 0.008, 0.022, 0.040, 0.042 and 0.062 h --1 enabling the correlation of
the mean specific growth rates with productivity results. Finally, a feed rate
of 0.086 h --1 corresponding to a mean specific growth rate of 0.070 h --1
allowed a specific productivity of 1.27 mg of mycosubtilin g --1 of dried
biomass h --1 .
