弗氏柠檬酸杆菌富硒发酵工艺优化

Optimization of Selenium-Enriched Fermentation by CitrobacterFreundii

纳米硒作为一种安全高效的材料,在食品、医药、半导体等领域受到广泛应用。由于生物相容性高的优点,生物合成纳米硒也成为研究热点。从福建省富硒土壤中筛选出一株具有较高还原亚硒酸钠能力的菌株,转化率48 h高达75%,并对该菌株进行理化性质等分析,结果表明该菌为弗氏柠檬酸杆菌(Citrobacter freundii)。为增加菌丝生物量,提高转化率,以柠檬酸杆菌光密度为指标,通过单因素试验和Box-Behnken试验,对菌株的培养工艺进行优化。结果表明,最佳培养条件为酵母提取物24.49 g/L、酪蛋白胨13.15 g/L、K_(3)PO_(4)1 g/L、NaCl 10 g/L、pH6.4,在此优化条件下,菌丝生物量达到1.51 g/L,转化速率提高2.40倍,24 h可转化89%的亚硒酸钠。

As a safe and efficient material,nano selenium has been widely used in food,medicine,semiconductor and other fields.Due to the advantages of high biocompatibility,the bio-synthesis of nano-selenium has also become a research hotspot.A strain with a high reduction ability of sodium selenite was screened from selenium-rich soil in Fujian province.The conversion rate could reach 75%after 48 h.The physical and chemical properties of the strain were analyzed,and the results indicated that the strain was Citrobacter freundi.In order to increase the mycelial biomass and conversion rate,the optical density of Citrobacter was used as an index to optimize the culture process of Citrobacter by single factor experiment and Box-Behnken experiment.The results showed that under the optimal conditions with yeast extract 24.49 g/L,casein peptone 13.15 g/L,K_(3)PO_(4)1 g/L,NaCl 10 g/L and the pH value 6.4,the mycelium biomass reached 1.51 g/L,the transformation rate increased by 2.40 times,and 89%of sodium selenitecouldbetransformed in 24h.