Continuous production of lacticin 3147 and nisin using cells immobilized in calcium alginate

Bacteriocinogenic strains, Lactococcus lactis subsp. lactis DPC 3147 and L. lactis DPC 496, producing lacticin 3147 and nisin, respectively, were immo bilized in double-layered calcium alginate beads. These beads were inoculat ed into MRS broth at a ratio of 1:4 and continuously fermented for 180 h. F ree cells were used to compare the effect of immobilization on bacteriocin production. After equilibrium was reached, a flow rate of 580 ml h(-1) was used in the immobilized cell (IC), and 240 ml h(-1) in free-cell (FC) biore actors. Outgrowth from beads was observed after 18 h. Bacteriocin productio n peaked at 5120 AU ml(-1) in both IC and FC bioreactors. However, FC produ ction declined after 80 h to 160 AU ml(-1) at the end of the fermentation. Results of this study indicate that immobilization offers the possibility o f a more stable and long-term means of producing lacticin 3147 in laborator y media than with free cells.