Marine heterotrophic dinoflagellate Crypthecodinium cohnii is an aerobic oleaginous microorganism that accumulates intracellular lipid with high content of 4,7,10,13,16,19-docosahexaenoic acid (DHA), a polyunsaturated ω−3 (22:6) fatty acid with multiple health benefits. C. cohnii can grow on glucose and ethanol, but not on sucrose or fructose. For conversion of sucrose-containing renewables to C. cohnii DHA, we investigated a syntrophic process, involving immobilized cells of ethanologenic bacterium Zymomonas mobilis for fermenting sucrose to ethanol. The non-respiring, NADH dehydrogenase-deficient Z. mobilis strain Zm6-ndh, with high ethanol yield both under anaerobic and aerobic conditions, was taken as the genetic background for inactivation of levansucrase (sacB). SacB mutation eliminated the levan-forming activity on sucrose. The double mutant Zm6-ndh-sacB cells were immobilized in Ca alginate, and applied for syntrophic conversion of sucrose to DHA of C. cohnii, either taking the ethanol-containing fermentation medium from the immobilized Z. mobilis for feeding to the C. cohnii fed-batch culture, or directly coculturing the immobilized Zm6-ndh-sacB with C. cohnii on sucrose. Both modes of cultivation produced C. cohnii CCMP 316 biomass with DHA content around 2–3 % of cell dry weight, corresponding to previously reported results for this strain on glucose.

海洋异养鞭毛藻Crypthecodinium cohnii是一种好氧产油微生物，可在细胞内积累高含量的 4,7,10,13,16,19-二十二碳六烯酸 (DHA)，一种多不饱和 ω-3 (22:6) 脂肪酸，具有多种对健康的益处。C. cohnii可以在葡萄糖和乙醇上生长，但不能在蔗糖或果糖上生长。为了将含蔗糖的可再生能源转化为C. cohnii DHA，我们研究了一个同养过程，该过程涉及产乙醇细菌运动发酵单胞菌的固定细胞，用于将蔗糖发酵成乙醇。非呼吸的，NADH脱氢酶缺陷型运动发酵单胞菌株Zm6- NDH，在厌氧和有氧条件下均具有高乙醇产量，被视为果聚糖蔗糖酶 ( sacB )失活的遗传背景。SacB突变消除了对蔗糖的果聚糖形成活性。双突变体Zm6- NDH -的sacB固定化细胞在藻酸钙，并申请了到的DHA蔗糖互养转化C.甲藻，无论是采取从固定在含有乙醇的发酵培养基运动发酵单胞用于馈送到C.甲藻补料分批培养，或直接共培养固定Zm6- NDH -的sacB与C.甲藻在蔗糖上。两种培养模式都产生了C. cohnii CCMP 316 生物量，其 DHA 含量约为细胞干重的 2-3%，与之前报道的该菌株对葡萄糖的结果一致。