Abstract:

The effects of melatonin on the biomass and lipid production in Monoraphidium sp. FXY-10 under molasses wastewater were studied. The molasses wastewater was used as a growth media for the cultivation of Monoraphidium sp. FXY-10. Lipid content of algae was reached 68.69 % with 10^-3μmol/L melatonin-treated, which was increased by 1.15-fold. The biomass was 1.22g/L, representing 41.86% higher than that of single molasses wastewater. And the protein and carbohydrate contents were increased and decreased by 1.41- and 0.61-fold, respectively. The removal rate of COD, total nitrogen and total phosphorus in molasses waste mash reached 92.33%, 90.07% and 86.04%, respectively in the microalgae cultivation. Furthermore, the lipid biosynthesis-related enzyme activities correlated with the increased lipid accumulation. The ACCase, and ME activities were considerably up-regulated with PEPC activity but were significantly down-regulated by melatonin induction. The yield analysis indicated that 1kg dried biomass of Monoraphidium sp. FXY-10 might produce about 535.8g of biodiesel. These low cost findings demonstrated that exogenous melatonin could promote the biomass and lipid production in microalgae under molasses wastewater, and provide a theoretical basis for the large-scale microalgae cultivation.

Key words: molasses wastewater, melatonin, Monoraphidium sp. FXY-10, biomass, lipid

摘要：

研究褪黑素对糖蜜酒精废醪液中单针藻Monoraphidium sp. FXY-10生长和油脂积累的影响。结果表明，以糖蜜酒精废醪液为基础培养基，添加10^-3μmol/L的褪黑素，微藻中的油脂含量达到68.69%，是对照组的1.15倍，且最高生物量为1.22g/L，相比对照组提高了41.86 %。与对照组相比，藻细胞内蛋白质和碳水化合物含量分别是对照组的0.61和1.41倍。在微藻培养过程中，糖蜜废醪液中的COD、总氮及总磷的清除率分别达到92.33%、90.07%和86.04%。此外，外源褪黑素的添加提高了乙酰辅酶A羧化酶（acetyl coenzyme A carboxylase，ACCase）、苹果酸酶（malic enzyme，ME）的活性，而降低了磷酸烯醇式丙酮酸羧化酶（phosphoenolpyruvate carboxylase，PEPC）的活性。初步技术经济分析表明，1kg单针藻Monoraphidium sp. FXY-10的干燥粉可以制备535.8g生物柴油。研究表明，褪黑素可以促进糖蜜酒精废醪液中微藻的生长和油脂的积累，降低培养成本，为微藻扩大化生产提供了新的理论基础。

关键词: 糖蜜酒精废醪液, 褪黑素, 单针藻Monoraphidium sp. FXY-10, 生物量, 油脂