Enhancing of nisin production in a bioreactor by co-culture of Lactococcus lactis and Yarrowia lipolytica

Nisin is the first FDA-approved food preservative produced by Lactococcus lactis at industrial scale. The negative effect of lactic acid produced by metabolism of Lactococcus lactis subsp. lactis, on nisin production, was removed by co-culture of Lactococcus lactis with Yarrowia lipolytica yeast. In the present study, the co-culture of Lactococcus lactis subsp. lactis and Yarrowia lipolyticawas performed for the first time inmolasses-based medium at 30°C, pH 6, 100 rpm, 0.15 vvm was applied in a laboratory scale bioreactor. Nisin production was measured as 920 IU/mL. The results showed that co-culture fermentation increased biomass and nisin production up to 63% and 78%, respectively. Other factors such as extracellular proteolytic activity of the yeast should be taken into consideration, which in turn make the culture nutrients more available to the bacterium.