A strategy of phosphorus feeding for repeated fed-batch fermentation of penicillin G

The critical “withdraw and fill” procedure is adopted for the efficient industrial fermentation of Penicillium chrysogenum to produce penicillin G. In order to maintain the elemental balance of the growing mycelia and to provide optimal conditions for penicillin G biosynthesis, a novel strategy of phosphorus feeding is reported. The required phosphorus to feed was calculated by the mass flow distribution and the phosphorus composition of the growing mycelia. The optimal amount of supplied phosphorus was experimentally determined for repeated fed-batch process. Initially, inorganic phosphorus source, such as KH2PO4, was effective. But, a combination of inorganic KH2PO4 with organic phosphorus, such as corn steep liquor, showed the best results. Feeding KH2PO4 together with corn steep liquor after the first withdrawal improved the penicillin titers by 16.1% on average. Our fermentation experiments and validation processes showed that feeding phosphorus was an efficient way to improve the production of penicillin G. This phosphorus feeding strategy might also be useful to improve the fermentation processes of other industrial biological products.