Optimisation on the High-Density Culture of Lactobacillus sakei Based on Fermenter and Its Freeze-Dried Bacterial Powder Process
In order to obtain methods for high-density culture of Lactobacillus sakei and its freeze-dried bacterial powder preparation process,the fermentation medium,fermentation conditions of seed solution and fermentation tanks,centrifugation parameters and freeze-dried protectant were studied by designing single-factor and orthogonal experiments.The results determined that the medium is sucrose 30 g/L,yeast extract powder 35 g/L,manganese sulphate 0.25 g/L,dipotassium hydrogen phosphate 3.0 g/L,diammonium hydrogen citrate 3.0 g/L,sodium acetate 7.5 g/L,Tween 80 1.5 g/L,magnesium sulphate 0.87 g/L,culture temperature 30 ℃,shake flasks initial pH 7.5,the seed solution culture 10-20 h,fermentation tanks constant pH 6.0,stirring speed 50 r/min,non-aerated culture,adding 0.2％polyether defoamer,selecting 4 mol/L sodium hydroxide as neutraliser,replenishing 30％sucrose,centrifugation speed of 6000 r/min,centrifugation time of 10 min,and 10％honey as freeze-dried protectant,the biomass OD620 nm increased to 8.91 under this condition,and the number of viable bacteria,the survival rate,and the moisture content of the freeze-dried bacterial powder reached 6.27×1011 CFU/g,88.08％and 2.94％,respectively.In this study,the biomass of fermentation broth and bacterial powder was significantly increased by optimizing the high-density cultivation and bacterial powder preparation process of Lactobacillus sakei,which can lay the foundation for the industrial production of Lactobacillus sakei and its bacterial powder.
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