富硒酵母的分离鉴定及富硒条件的优化

富硒酵母生产发酵食品是补充硒元素的有效方法，以实验室保存的酵母菌为材料，通过选择培养基平板稀释法，分离纯化得 到四株富硒酵母，经形态学和分子生物学鉴定，初步鉴定菌株Z4、Z5、Z7、Z9均为库德毕赤酵母（Pichia kudriavzevii）。 通过对比四株菌 的生长曲线及富硒能力，发现Z5菌株生长状况最好，选取接种量、碳源（葡萄糖）和氮源（蛋白胨）添加量作为单一因素，通过单因素 试验和正交试验，探究各影响因素对菌株Z5富硒能力的影响。 结果表明，Z5菌株的最佳富硒发酵条件为接种量10%，葡萄糖2.4%，蛋 白胨1.8%。 在此最佳条件下，菌株Z5生物量为9.63 g/L，总硒含量可达到862 μg/g。

Isolation and identification of selenium-enriched yeast and optimization of selenium-enriched conditions

Fermented food produced by selenium-enriched yeast is an effective method for supplementing selenium. Four selenium-enriched yeasts were isolated from the yeast stored in the laboratory and purified by selective medium dilution method, after morphology and molecular biology iden- tification, the results showed that strain Z4, Z5, Z7 and Z9 were identified as Pichia kudriavzevii. The strain Z5 with good growth condition was obtained by comparing the growth curves and selenium enrichment capacities of the four strains. The inoculum, carbon source (glucose) and nitrogen source (peptone) addition were selected as single factors, and the effect of each influencing factors on selenium-enriching ability of the strain Z5 was investi- gated by single factor and orthogonal experiments. The results showed that the optimal selenium-enriched conditions of strain Z5 were inoculum 10%, glucose 2.4% and peptone 1.8%. Under the optimal conditions, the biomass and total selenium content of strain Z5 was 9.63 g/L and 862 μg/g, respectively.