高转化大豆异黄酮乳酸菌的筛选及在豆乳中的发酵特性

为提高大豆异黄酮生物活性及利用度,该研究以含七叶苷和柠檬酸铁的特殊培养基,从实验室保藏的人源乳酸菌中筛出产β-葡萄糖苷酶目标菌株,并采用高效液相色谱法测定其发酵豆乳转化大豆异黄酮的能力,分析持水力、产酸速率和发酵末活菌数。结果显示,从140株乳酸菌中筛出的12株目标菌株,菌株58和菌株m91发酵豆乳产大豆异黄酮苷元能力最强,总量分别达59.64、58.06 mg/L,均在原豆乳的8倍以上,显著高于其余乳酸菌(P<0.05)。在发酵豆乳基本特性研究中表明,菌株58发酵豆乳持水力为35.10%,发酵末活菌数为8.78 lg(CFU/mL),到达发酵终点用时11.50 h,并且产酸速率快。经16S rDNA测序及系统发育分析,优选菌株58为植物乳杆菌。

Screening of Lactic Acid Bacteria with High Conversion of Soybean Isoflavones and Fermentation Characteristics in Soybean Milk

In order to improve the biological activity and utilization of soybean isoflavone,the target strain producingβ-glucosidase was screened from human lactic acid bacteria preserved in the laboratory in a special medium containing aescin and iron citrate.The transformation ability of soybean isoflavone was determined by high performance liquid chromatography and the water holding capacity,acid production rate and the number of viable bacteria in the end of fermentation were analyzed.The results showed that among the 12 target strains screened out from 140 strains of lactic acid bacteria,strain 58 and strain m91 had the strongest ability to produce soybean isoflavone aglycones with the total amount of 59.64 mg/L and 58.06 mg/L,respectively,which were more than 8 times of that of the original soybean milk,significantly higher than that of other lactic acid bacteria(P<0.05).The results showed that the water holding capacity of strain 58 was 35.10%,the number of viable bacteria was 8.78 lg(CFU/mL),it took 11.50 h to reach the end of fermentation,and the acid production rate was fast. By 16S rDNA sequencing and phylogenetic analysis, the optimal strain 58 was Lactobacillus plantarum.