雪莲菌富硒条件优化及体外抗氧化活性分析

Optimization of Selenium Enrichment Procedure for Tibetan Kefir Grains with Antioxidant Activity

利用雪莲菌吸收和转化无机硒为有机硒,旨在通过优化富硒条件制备菌活性和有机硒占比较高的富硒雪莲菌。针对不同优化需求,确定不同优化指标,从而选择最佳的富硒条件。优化后富硒温度为28℃、富硒时间为24 h、亚硒酸钠添加时间为雪莲菌接种后3 h;通过摇床培养,进行梯度驯化富硒;以透析后总硒含量占比、生物量、富硒率(selenium enrichment rate,SER)和有机硒占比(organic selenium percentage,OSP)确定梯度富硒底物浓度为3、6、9、12、15μg/mL。在最优富硒条件下所制备的富硒雪莲菌的总硒含量(total selenium content,TSC)为(2 194.41±58.49)μg/g,有机硒占比为(84.57±1.45)%。通过抗氧化活性测定发现富硒雪莲菌的抗氧化活性极显著高于雪莲菌(P<0.001)。

Tibetan kefir grains(TKGs)were used to absorb and convert inorganic selenium to organic selenium.The selenium enrichment procedure was optimized to produce the selenium-enriched Tibetan kefir grains(Se-TKGs)with high microbial activity and organic selenium percentage(OSP).The optimal procedure was determined as selenium enrichment at 28℃for 24 h,with the addition of sodium selenite 3 h after the inoculation of TKGs.Shaking incubation was employed to enrich selenium by the concentration gradient domestication method.The total selenium percentage after dialysis,biomass,selenium enrichment rate,and OSP were used to determine the substrate concentration for selenium enrichment are 3,6,9,12,15μg/mL.The total selenium content of Se-TKGs prepared under the optimal selenium enrichment conditions was(2194.41±58.49)μg/g,containing(84.57±1.45)%organic selenium.Moreover,Se-TKGs had much higher antioxidant activity than TKGs(P<0.001).