植物乳植杆菌的高密度培养工艺优化与发酵特性研究

Optimization of High-density Cultivation Process and Investigation of Fermentation Characteristics of Lactiplantibacillus plantarum

摘要:

【目的】针对益生菌传统培养技术发酵密度低、周期长、抗逆性弱等问题，优化益生菌发酵工艺、提升菌体密度并增强菌株抗逆性。【方法】利用植物乳植杆菌FMBL L23251 FJX进行高密度发酵，在采用单因素试验与响应面法优化发酵工艺的基础上，进一步探究其代谢特性与菌粉制备的抗逆性。【结果】在麦芽汁料液比250 g∶1 L、酵母提取物添加量40 g/L、无水乙酸钠添加量6 g/L、低聚半乳糖添加量14 g/L、接种体积分数6%、转速100 r/min、pH 6.5条件下，于37 ℃发酵24 h后，发酵液中植物乳植杆菌FMBL L23251 FJX的活菌数高达2.33×10¹² CFU/mL，冻干菌粉活菌数高达3.56×10¹³ CFU/g，其在模拟胃肠液消化后的存活率为76.75%。相较于MRS培养基，植物乳植杆菌FMBL L23251 FJX在大麦芽汁培养基中的ABTS⁺自由基、DPPH自由基、羟自由基和超氧阴离子自由基清除率分别提升了19.93%、29.26%、25.19%、29.32%；总酚和总黄酮质量浓度分别增加了51.96%和30.66%；有机酸、短链脂肪酸及氨基酸的总质量浓度分别提高了99%、89%、48%。【结论】该研究可为本土来源益生菌在食品加工和生物医药等领域的规模化应用提供数据支撑。

Abstract:

[Objective] The conventional probiotic cultivation techniques suffer from problems such as low fermentation density, long cycles, and weak stress resistance, this study aimed to optimize the probiotic fermentation process, increase bacterial density, and enhance strain stress resistance.[Method] Lactiplantibacillus plantarum (L. plantarum) FMBL L23251 FJX was used for high-density fermentation. The fermentation process was optimized through single-factor experiments combined with response surface methodology. On this basis, the metabolic characteristics and the stress resistance of the prepared bacterial powder were further characterized. [Result] Under the malt extract-liquid ratio of 250 g∶1 L, yeast extract addition of 40 g/L, anhydrous sodium acetate addition of 6 g/L, galactooligosaccharide addition of 14 g/L, inoculum volume fraction of 6%, rotation speed of 100 r/min, pH 6.5, and fermentation at 37 ℃ for 24 h, the viable cell counts of L. plantarum FMBL L23251 FJX in the fermentation broth and freeze-dried powder reached 2.33×10¹² CFU/mL and 3.56×10¹³ CFU/g, respectively. The survival rate of L. plantarum FMBL L23251 FJX in the simulated gastrointestinal fluid was 76.75%. Compared with that in the MRS medium, L. plantarum FMBL L23251 FJX in barley malt wort medium showed increases of 19.93%, 29.26%, 25.19%, and 29.32% in scavenging rates against ABTS⁺, DPPH, hydroxyl, and superoxide anion free radicals, respectively. In addition, the mass concentration of total phenols and total flavonoids increased by 51.96% and 30.66%, respectively, while the total mass concentration of organic acids, short-chain fatty acids, and amino acids increased by 99%, 89%, and 48%, respectively. [Conclusion] This study provides data support for the large-scale application of locally sourced probiotics in food processing, biomedicine, and other fields.