Selective fengycin production in a modified rotating discs bioreactor.

Production of lipopeptides fengycin and surfactin in rotating discs bioreactor was studied. The effects of rotation velocity and the addition of agitators between the discs on volumetric oxygen transfer coefficient k L a were firstly studied in model media. Then the production of lipopeptides was also studied at different agitation conditions in the modified bioreactor (with agitators). The effect of agitation on dissolved oxygen, on submerged and immobilized biomass, on lipopeptide concentrations and yields and on the selectivity of the bioreaction was elucidated and discussed. The proposed modified rotating discs bioreactor allowed to obtain high fengycin concentrations (up to 787 mg L(-1)), but also better selectivity of the bioreaction towards fengycin (up to 88%) and better yields of fengycin per glucose (up to 62.9 mg g(-1)), lipopeptides per glucose (up to 71.5 mg g(-1)), fengycin per biomass (up to 309 mg g(-1)) and lipopeptides per biomass (up to 396 mg g(-1)) than those reported in the literature. Highest fengycin production and selectivity were obtained at agitation velocity of 30 min(-1). The proposed non-foaming fermentation process could contribute to the scale-up of lipopeptide fermentors and promote the industrial production of fengycin. The proposed bioreactor and bioprocess could be very useful also for the production of other molecules using bioprocesses requiring bubbleless oxygen supply.