促进裂殖壶菌发酵产二十碳五烯酸的两阶段控温和低溶氧策略

Two-Stage Temperature Control and Low-Dissolved-Oxygen Strategy for Efficient Eicosapentaenoic Acid Production by Schizochytrium

二十碳五烯酸(EPA)是一种具有重要生理功能的n3-多不饱和脂肪酸,在保健食品、药品、饲料等行业具有广阔的商业前景,传统的鱼油来源难以满足EPA日益增长的市场需求。文中以裂殖壶菌为出发菌株,通过单因素实验在摇瓶水平优化了发酵温度,在5 L发酵罐中进一步研究变温时间和溶氧对裂殖壶菌产EPA发酵性能的影响,建立了两阶段控温和低溶氧发酵策略,并研究了发酵过程中脂肪酸各组分的变化情况。结果表明,裂殖壶菌在阶段控温(28℃(0~24 h)→34℃(24~120 h))培养时,EPA含量最高,达到8.35%;在5 L发酵罐中确定了最佳变温时间为24 h,不同溶氧研究表明,中高溶氧(10%DO和25%DO)有利于裂殖壶菌的生长和油脂积累,但低溶氧(2%DO)更利于EPA的积累,EPA含量分别是中、高溶氧水平的2.05倍和4.98倍;建立了一种两阶段控温和低溶氧发酵策略,发酵至96 h时生物量、油脂产量、EPA含量和EPA产量分别达到56.60 g/L、9.62 g/L、12.50%和1.14 g/L,与优化前相比,EPA的含量和产量分别提高了14.5倍和6.1倍。

Eicosapentaenoic acid(EPA)is a kind of n3-polyunsaturated fatty acid with important physiological functions.It has broad commercial prospects in health food,medicine,feed and other industries.However,the deep-sea fish oil as the traditional source of EPA cannot meet the increasing market demand.In this paper,Schizochytrium was taken as the original strain,and a two-stage temperature and low-dissolved-oxygen(TST-LDO)strategy is proposed.The effect of fermentation temperature was optimized by single factor experiment at the shaking flask level,and the effects of two-stage temperature change time and dissolved oxygen on the fermentation performance of EPA production in Schizochytrium were studied in a 5 L fermenter.The change of fatty acid components in the process of fermentation was studied.The results show that the highest EPA content(8.35%)is obtained at two-stage-temperature strategy(28℃(0~24 h)→34℃(24~120 h)).The optimal temperature change time is 24 h,which is determined in a 5 L fermenter.The results of different dissolved oxygen studies show that the medium and high dissolved oxygen(10%DO and 25%DO)are more conducive to the growth and lipid accumulation of Schizochytrium,but the low dissolved oxygen(2%DO)is more conducive to the accumulation of EPA,and the content of EPA is 2.05 times and 4.98 times of the medium and high dissolved oxygen level,respectively.When fermentation reached 96 h under TST-LDO strategy,the biomass,lipid yield,EPA content in total fatty acid and EPA yield reached 56.60 g/L,9.62 g/L,12.50%and 1.14 g/L,respectively.Compared with the pretreatment,EPA content and EPA yield increased by 14.5 times and 6.1 times,respectively.