素食者产雌马酚肠道菌生长条件优化

Growth Characteristics of Equol-Producing Bacterial Strains from the Intestinal Tract of Vegetarians and Optimization of Culture Conditions for Enhanced Equol Production

以菌落数和光密度值以及雌马酚含量为评价指标,测定两株肠道菌的生长曲线,考察金属盐Mn SO4、Zn SO4、Ca Cl2、Na2CO3、KNO3对其生长状况的影响,筛查其对不同碳源(葡萄糖、麦芽糖、蔗糖、果糖、乳糖)的利用情况。其次采用单因素试验和正交试验对生长条件进行优化。结果表明:LJ-G1和LJ-Q2两株菌的生长规律为在37℃厌氧条件下,培养6h后进入指数期、21h后进入生长平稳期、39h后为衰亡期。金属盐对菌株生长均有抑制作用,作用最强的为Mn SO4;葡萄糖对肠道菌的生长有促进作用。生长最优条件为:培养基中葡萄糖质量浓度7g/L、p H7.2、Na Cl质量浓度2g/L,雌马酚的产量较高为11.89μg/m L。

Two anaerobes isolated from the feces of female vegetarians, LJ-G1 and LJ-Q2, were demonstrated to capable of metabolizing soybean isoflavones to produce equol. The number of colonies, optical density and equol production was plotted against culture period for either of the two strains. The impact of Mn SO4, Zn SO4, Ca Cl2, Na2CO3 and KNO3 on bacterial growth was explored. Meanwhile, the utilization of different carbon sources such as lactose, maltose, sucrose, corn starch and glucose by the anaerobic strains was screened. The culture conditions for equol production were optimized by single factor and orthogonal array designs. The results showed that LJ-G1 and LJ-Q2 were preferred to grow at 37 ℃under anaerobic conditions. Their growth was at the exponential phase after 6 h of cultivation, the stationary phase after 21 h and the decline phase after 39 h. All investigated metal salts could inhibit the growth of the strains, with Mn SO4 being the strongest inhibitor, whereas glucose had a positive effect on the growth of these intestinal strains. The optimized culture conditions that provided a higher equol production of 11.89 μg/m L were 7 g/L glucose and 2 g/L Na Cl in the medium withan initial p H of 7.2.