Han Lijie, Wang Weiliang, Wan Minxi, Shen Guomin, Yu Tao, Li Yuanguang
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.
Sheng Wu Gong Cheng Xue Bao. 2022 Dec 25;38(12):4756-4764. doi: 10.13345/j.cjb.210423.
Selenium (Se) is an essential trace element for organisms. Se deficiency will cause diseases such as Keshan disease and Kashin-Beck in human being, and huge loss to animal husbandry. Currently available Se supplements have such problems as low Se content, poor bioavailability, and poor safety. can produce bioavailable and safe organic Se under suitable conditions, which is thus a promising Se supplement. Therefore, in this study, we tried to improve the Se tolerance and accumulation of by directional adaptation. To be specific, we gradually increased the concentration of NaSeO in medium to domesticate and optimized the adapting time and concentration gradient of NaSeO during the adaptation. The results showed that the adapted was more tolerant to Se and had stronger Se enrichment ability. In 5 L fermenter, the adapted strains could tolerate 40 mg/L NaSeO and the synthesis rate of organic Se was 175.6% higher. Then, Se addition method in the 5 L fermenter was optimized. The result demonstrated that addition of NaSeO at 40 mg/L during heterotrophic culture achieved the final dry weight of cells at 106.4 g/L, content of organic Se at 1 227 mg/kg, and synthesis rate of organic Se at 1.36 mg/(L·h). Compared with the reported highest cell density of 75 g/L and the highest organic Se content of 560 mg/kg, the corresponding figures in this study were 41.9% and 119.1% higher, respectively. In conclusion, directional adaptation can remarkably improve the Se tolerance and enrichment of .
硒（Se）是生物体必需的微量元素。缺硒会导致人类患上克山病和大骨节病等疾病，并给畜牧业造成巨大损失。目前可用的硒补充剂存在硒含量低、生物利用度差和安全性差等问题。在合适的条件下能够产生具有生物利用度且安全的有机硒，因此是一种有前景的硒补充剂。所以，在本研究中，我们试图通过定向驯化来提高其对硒的耐受性和积累能力。具体而言，我们在培养基中逐渐增加亚硒酸钠（NaSeO）的浓度来驯化它，并在驯化过程中优化亚硒酸钠的适应时间和浓度梯度。结果表明，驯化后的对硒更具耐受性且具有更强的硒富集能力。在5升发酵罐中，驯化后的菌株能够耐受40毫克/升的亚硒酸钠，有机硒的合成速率提高了175.6%。然后，对5升发酵罐中的硒添加方法进行了优化。结果表明，在异养培养期间添加40毫克/升的亚硒酸钠，细胞的最终干重达到106.4克/升，有机硒含量为1227毫克/千克，有机硒合成速率为1.36毫克/（升·小时）。与报道的最高细胞密度75克/升和最高有机硒含量560毫克/千克相比，本研究中的相应数值分别高出41.9%和119.1%。总之，定向驯化能够显著提高其对硒的耐受性和富集能力。
