富硒酵母发酵工艺的优化

以富硒酿酒酵母（Saccharomyces cerevisiae）SY2为发酵菌种，利用5 L发酵罐培养富硒酵母。以富硒酵母生长及硒转化率为评价指标，优化其发酵工艺条件，比较溶氧反馈补料与拟指数补料两种方式对富硒酵母生长、硒转化率等的影响。结果表明，富硒酵母最适发酵条件为：初始pH 5.0，发酵温度30℃，接种量8%，硒添加量30 mg/L，发酵时间24 h。在此优化条件下，富硒酵母生物量为9.8 g/L，硒转化率为77.5%。在拟指数补料方式下，培养周期为34 h，富硒酵母得率为0.252 g/g，硒含量为1 920.5μg/g，硒的转化率为82.7%；在溶氧反馈补料方式下，培养周期为46 h，富硒酵母得率为0.317 g/g，硒含量为1 759.5μg/g，硒转化率为90.1%。结果显示，拟指数补料培养周期短，生产强度、酵母硒含量较高，是适宜补料方式。

Optimization of fermentation technology of selenium-riched yeast

Using Saccharomyces cerevisiae SY2 as fermentation strain, the selenium-enriched yeast was fermented in a 5 L fermenter. Using the growth and selenium conversion rate of selenium-enriched yeast as evaluation indexes, the fermentation conditions were optimized, and the effects of dissolved oxygen feedback feeding and quasi-exponential feeding on the growth and selenium conversion rate of selenium-enriched yeast were compared. The results showed that the optimal fermentation conditions of selenium-enriched yeast were initial pH 5.0, fermentation temperature 30 ℃, inoculum 8%, selenium addition 30 mg/L and time 24 h. Under the optimized conditions, the biomass of selenium-enriched yeast was 9.8 g/L, and the selenium conversion rate was 77.5%. Under the quasi-exponential feeding method, the fermentation time was 34 h, the yield of selenium-enriched yeast was 0.252 g/g, the content of selenium was 1 920.5 μg/g, and the selenium conversion rate was 82.7%. Under the dissolved oxygen feedback feeding method, the fermentation time was 46 h, the yield of selenium-enriched yeast was 0.317 g/g, the content of selenium was 1 759.5 μg/g, and the selenium conversion rate was 90.1%. The results shown that the quasi-exponential feeding with short culture cycle, high production intensity and high yeast selenium content was the optimal feeding method.