Abstract:

The fermentation broth of Lactobacillus paracasei HD1.7 found in the Chinese sauerkraut contains bacteriocin Paracin 1.7, it has the potential to become a new type of food preservative depending on its broad spectrum of inhibition. This study aims to increase the yield of bacteriocin Paracin1.7. Using L. paracasei HD1.7 as the starting strain, high-density culture of fermenter was used to optimize single-factor fermentation conditions and conduct orthogonal design to increase the yield of bacteriocin Paracin1.7. The results showed that during the fermentation process, the optimal inoculum was 3%, the optimal inoculum age was 18 h, the optimal liquid volume was 2 L/3.7 L, the optimal initial pH value was pH 5.5, and the optimal aeration was 0 L/min, the optimal rotational speed was 400 r/min, the optimal culture temperature was 35℃, and the optimal culture time was 24 h. Under the above optimized conditions, the titer of bacteriocin Paracin 1.7 in the fermentation broth was increased from 863.01±39.77 AU/mL before optimization to 978.46±7.16 AU/mL, which was 1.13 times of the original, and the density of the bacteria reached 10¹⁰ CFU/mL. By optimizing the fermentation conditions, the biomass and bacteriocin production of L. paracasei HD1.7 can be significantly improved, and the experimental basis for designing and improving high-density cultured cells is laid.

Key words: Lactobacillus paracasei HD1.7, high-density culture, bacteriocin Paracin 1.7, single factor fermentation optimization, orthogonal test