Colin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, Shandong, People's Republic of China.
Lett Appl Microbiol. 2022 Dec;75(6):1617-1627. doi: 10.1111/lam.13829. Epub 2022 Sep 28.
Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) are important dietary components due to their health benefits and preventative role in cardiovascular disease. Fish-based and plant seed oils are rich in stearidonic acid (SDA; 18:4, n-3), which are readily metabolized into ω-3 PUFAs such as eicosapentaenoic acid. However, these natural sources of SDA are generally low yielding and are unlikely to meet global demands, so new sustainable microbial fermentative sources of SDA need to be identified. Expression of delta15-desaturase in the oleaginous filamentous fungus Mucor circinelloides (McD15D) has been used to construct a recombinant SDA-producing McD15D strain that produces 5·0% SDA levels using submerged fermentation conditions. Switching to solid-state fermentation conditions in the same medium with submerged fermentation resulted in this engineered strain producing significantly higher amounts of SDA. A Box-Behnken design of response surface methodology approach has been used to identify optimal glucose and ammonium tartrate concentrations and temperature levels to maximize SDA production. The use of these optimal solid-state fermentation conditions resulted in the spores and mycelium of the recombinant McD15D producing 19·5% (0·64 mg g ) and 12·2% (1·52 mg g ) SDA content, respectively, which represents an overall increase in SDA yield of 188·0% compared with SDA yields produced using submerged fermentation conditions.
ω-3 多不饱和脂肪酸（PUFAs）是重要的膳食成分，因为它们具有健康益处，并在心血管疾病的预防中发挥作用。鱼类和植物种子油富含 stearidonic 酸（SDA；18:4，n-3），可轻易转化为 EPA 等 ω-3 PUFAs。然而，这些 SDA 的天然来源产量一般较低，不太可能满足全球需求，因此需要确定新的可持续微生物发酵 SDA 来源。在产油丝状真菌 Mucor circinelloides（McD15D）中表达 δ15-去饱和酶，构建了 SDA 生产型 McD15D 重组菌株，在液体发酵条件下可产生 5.0%的 SDA。在相同培养基中切换至固态发酵条件，可使该工程菌株产生更高水平的 SDA。采用 Box-Behnken 设计的响应面法来确定最佳葡萄糖和酒石酸铵浓度以及温度水平，以实现 SDA 的最大产量。采用这些最佳固态发酵条件，重组 McD15D 的孢子和菌丝体的 SDA 含量分别达到 19.5%（0.64mg/g）和 12.2%（1.52mg/g），与液体发酵条件相比，SDA 产量总体提高了 188.0%。
