Optimization of medium and pH control profile in biofilm fermentation for nisin production

In this study, biofilm reactor with Plastic Composite Support (PCS), made by high temperature extrusion of agricultural products and polypropylene, has been evaluated on nisin production using L. lactis NIZO 22186. High-biomass density characteristic of biofilm reactor was found to contribute in a significantly shorter lag time of nisin production. In comparison to glucose, sucrose significantly increased nisin production rate by 1.4-fold. However, obtained data also revealed a suppressing effect of high level of sucrose on nisin production and its stimulating effect on lactic acid production. High concentration of M_gSO₄7H₂O at 0.04% was found to reduce the nisin production, while concentration of KH₂PO ₄Of up to 3% did not have any significant effect on growth or nisin production. The optimal complex media for nisin production using PCS bio film reactor consisted of 4% sucrose, 0.02% MgSO₄JH₂O, and 0.1% KH₂PO⁴. Nisin production rate in biofilm reactor was significantly increased by 3.8-fold when using an optimized medium. Higher nisin could be obtained with a simple adjustment in the pH-control profile by allowing the pH to drop freely via autoacidification after 4 h of fermentation.