裂殖壶菌是替代深海鱼油产业化生产二十二碳六烯酸(docosahexaenoic acid, DHA)油脂的极具潜力的微生物。该研究采用1株裂殖壶菌DP-16发酵产油脂,以葡萄糖为碳源,以酵母浸粉和谷氨酸钠为氮源,以KH2PO4为磷源,探究了氮、磷源浓度对菌体生长、葡萄糖消耗和油脂积累的影响。结果显示,在正常氮、磷源浓度下培养菌体,0~24 h为细胞增殖期,24~84 h为油脂积累期,在84 h油脂产量和油脂含量分别达到14.1 g/L和33.5%,84~96 h进入油脂反耗期。改变氮、磷源浓度,低磷条件下72 h的油脂产量和油脂含量分别达到14.8 g/L和44.3%,比对照组分别提高了5.0%和32.2%,而高氮、低氮、高磷等条件均不利于裂殖壶菌产油脂。研究结果表明,氮、磷源浓度对裂殖壶菌细胞生长和油脂积累产生重要影响,油脂产量取决于菌体生物量和细胞内油脂含量的乘积,为提高油脂产量,需要在获得高细胞浓度(生物量)和达到高油脂含量之间找到一个合适的平衡,以确定适宜的氮、磷源浓度。该研究对促进裂殖壶菌发酵产DHA油脂具有重要参考意义。
Schizochytrium sp. is now considered as a promising microorganism to replace marine fish oil for commercial production of DHA-rich lipid. In this study, effects of nitrogen source (yeast extract and monosodium glutamate) and phosphorus source (KH2PO4) concentration on the cell growth, glucose consumption and lipid accumulation in fermentation by Schizochytrium sp. DP-16 were investigated. The fermentation process in control medium containing normal nitrogen and phosphorus source concentration was analyzed. Stage 1 (0-24 h) was cell growth and proliferation stage; stage 2 (24-84 h) was lipid accumulation phase, and the lipid production and lipid content at 84 h reached 14.1 g/L and 33.5% respectively; stage 3 (84-96 h) was lipid turnover stage. Under low KH2PO4 concentration of 1 g/L, the lipid production and lipid content at 72 h reached 14.8 g/L and 44.3% respectively, increased by 5.0% and 32.2% respectively compared with the control group. However, high nitrogen, low nitrogen, high phosphorus and other conditions are not conducive to lipid production. The results showed that the concentration of nitrogen and phosphorus sources had an important effect on the cell growth and lipid accumulation of Schizochytrium sp. Therefore, to control the appropriate concentration of nitrogen and phosphorus source for efficient lipid production, an optimal balance needs to be found between attaining a high concentration of the biomass and a high lipid content in the biomass. This study provides valuable guidance for promoting DHA-rich lipid production by Schizochytrium sp.
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