Optimization of High-density Culture and Lyoprotectant for Lactobacillus plantarum BF_15 from Breast-fed Infants

ZHANG Na; ZHOU Yue; ZHU Weihong; HE Fuqiang; ZHANG Baoshi; TIAN Chunhao; PAN Yuhan; TIAN Hongtao; MIAO Xiaoyan; ZHAO Lina; JIAO Yulan

doi:10.13982/j.mfst.1673-9078.2025.11.1210

Abstract：In order to promote the industrialization of Lactobacillus plantarum BF_15 with multiple probiotic properties(such as immune regulation and cholesterol reduction)from breast-fed infants with clear genetic background.In this study,the medium components and culture conditions were optimized through single-factor combined with orthogonal experiments,and the lyoprotectants were optimized through single-factor experiments combined with specific formulation ratios.The results showed that the viable cell count of BF_15 in MRS Medium was 2.30×109 CFU/mL.The optimal medium composition obtained through single-factor combined orthogonal experiments was:fructooligosaccharides,30 g/L;nitrogen source(soy protein peptone:yeast extract=3:1),30 g/L;sodium acetate anhydrous,6 g/L;manganese sulfate,75 mg/L.Under these conditions,the viable cell count of BF_15 reached 6.93×109 CFU/mL.The optimal culture conditions:inoculation volume fraction,5%;incubation temperature,33℃;initial pH value 7.0;dissolved oxygen level,0 r/min.Under such conditions,a viable cell count of 8.92×109 CFU/mL was achieved,which was 3.88 times that before optimization.The optimal lyoprotectant formulation was:skim milk,100 g/L;bovine serum,10 ml/L;sucrose,80 g/L;sodium glutamate,20 g/L;yeast extract powder,15 g/L;Tween 80,10 ml/L.Under these conditions,the survival rate of BF_15 was 90.57%,with a viable cell count of 2.45×1010 CFU/mL.After a storage at 4℃for 56 days,the survival rate of the freeze-dried bacterial powder was 82.35%,with a viable cell count of 2.02×1010 CFU/mL.Following the gastrointestinal fluid treatment,the survival rate was 69.70%,with a viable cell count of 1.41×1010 CFU/mL.In summary,the high-density culture of Lactobacillus plantarum BF_15 was realized and highly viable bacteria preparations were obtained,which provides solid theoretical support for accelerating the industrialization process.