Fei Yongtao, Huang Li, Wang Hong, Liang Jinglong, Liu Gongliang, Bai Weidong
Guangdong Provincial Key Laboratory of Lingnan Specialty Food Science and Technology Zhongkai University of Agriculture and Engineering Guangzhou China.
College of Light Industry and Food Science Zhongkai University of Agriculture and Engineering Guangzhou China.
Food Sci Nutr. 2022 Feb 23;10(5):1548-1563. doi: 10.1002/fsn3.2779. eCollection 2022 May.
L6 isolated from naturally fermented tofu-whey was characterized as potential probiotics. To give insight into the adaptive mechanism of L6 in soymilk, the gene-expression profiles of this strain and changes of chemical components in fermented soymilk were investigated. The viable counts of L6 in soymilk reached 10 CFU/mL in the stationary phase (10 hr). The main sugars reduced gradually while the acidity value significantly increased from 45.33° to 95.88° during fermentation. About 50 genes involved in sugar metabolization and lactic acid production were highly induced during soymilk fermentation. The concentration of total amino acid increased to 668.38 mg/L in the logarithmic phase, and 45 differentially expressed genes (DEGs) in terms of nitrogen metabolism and biosynthesis of amino acid were detected. Other genes related to lipid metabolism, inorganic ion transport, and stress response were also highly induced. Besides, the concentration of isoflavone aglycones with high bioactivity increased from 14.51 mg/L to 36.09 mg/L during the fermentation, and the expression of 6-phospho--glucosidase gene was also synchronously induced. This study revealed the adaptive mechanism of L6 in the soymilk-based ecosystem, which gives the theoretical guidance for the application of this strain in other soybean-derived products.
从天然发酵的豆腐乳清中分离出的L6被鉴定为潜在的益生菌。为深入了解L6在豆浆中的适应机制，研究了该菌株的基因表达谱以及发酵豆浆中化学成分的变化。豆浆中L6的活菌数在稳定期（10小时）达到10⁸ CFU/mL。发酵过程中主要糖类逐渐减少，而酸度值从45.33°显著增加到95.88°。约50个参与糖代谢和乳酸产生的基因在豆浆发酵过程中被高度诱导。总氨基酸浓度在对数期增加到668.38 mg/L，检测到45个在氮代谢和氨基酸生物合成方面差异表达的基因（DEGs）。其他与脂质代谢、无机离子转运和应激反应相关的基因也被高度诱导。此外，具有高生物活性的异黄酮苷元浓度在发酵过程中从14.51 mg/L增加到36.09 mg/L，6-磷酸-β-葡萄糖苷酶基因的表达也被同步诱导。本研究揭示了L6在豆浆生态系统中的适应机制，为该菌株在其他大豆衍生产品中的应用提供了理论指导。
