The low-cost carbon source, acetate, was utilized to feed a linoleic acid-rich for microalgal biomass and lipid accumulation. Remarkably high tolerance capability to high acetate dosage up to 30 g/L was observed, with heterotrophy being the preferred trophic mode for algal growth and lipogenesis when supplemented 20 g/L acetate. Transcriptome analysis revealed a marked activation of pathways involved in acetate bioconversion and lipogenesis upon exposure to high-level of acetate. However, the enhancement of photorespiration inhibited photosynthesis, which ultimately led to a decrease in biomass and lipid under mixotrophy. Heterotrophic acetate-feeding generated more superior amino acid profiling of algal biomass and a predominant linoleic acid content (50 %). Heterotrophic repeat fed-batch strategy in 5 L fermenter significantly increased the growth performance and lipid titer, with the highest levels achieved being 23.4 g/L and 7.0 g/L, respectively. This work provides a viable approach for bio-products production through acetate-based heterotrophic algal cultivation.

中文翻译：

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使用高醋酸剂量异养培养富含亚油酸的产油微藻 Chlorella sorokiniana 同时生产藻类生物质和脂质

低成本的碳源乙酸盐被用来供给富含亚油酸的微藻生物量和脂质积累。观察到对高达 30 g/L 的高乙酸盐剂量具有显着的高耐受能力，当补充 20 g/L 乙酸盐时，异养是藻类生长和脂肪生成的首选营养模式。转录组分析显示，暴露于高水平的乙酸盐后，涉及乙酸盐生物转化和脂肪生成的途径显着激活。然而，光呼吸的增强抑制了光合作用，最终导致混合营养下生物量和脂质的减少。异养乙酸盐喂养产生了更优异的藻类生物质氨基酸谱和主要亚油酸含量（50%）。 5 L 发酵罐中的异养重复补料分批策略显着提高了生长性能和脂质滴度，最高水平分别为 23.4 g/L 和 7.0 g/L。这项工作为通过基于醋酸盐的异养藻类培养生产生物产品提供了一种可行的方法。