The aim of the present study was to investigate the effect of nitrate pulse feeding on the cell growth and cell composition of Desmodesmus sp.F51.Under nitrate pulse-feeding cultivation,the protein content of cells of Desmodesmus sp.FS1 decreased from (560 ± 16) mg/g to (456 ± 17) mg/g,while the contents of carbohydrate and lipid increased from (209 ± 13) mg/g to (310 ± 12) mg/g and (98 ± 3) mg/g to (120 ± 4) mg/g,respectively.By investigating the changes in carotenoid,lipid and carbohydrate compositions,it appeared that nitrate pulse feeding could promote β-carotene biosynthesis and enhance the bioconversion of α-carotene to lutein.Lutein accumulation was positively associated with polyunsaturated fatty acid formation.Desmodesmus sp.F51 tended to accumulate carbohydrate as an energy storage product after 3 days of cultivation under nitrate pulse-feeding conditions,and the major accumulated monosaccharide was glucose (75.7 ±1.4)％.Therefore,the nitrate-pulse feeding strategy is a highly promising approach to simultaneously produce lutein and carbohydrate in Desmodesmus sp.F51.%考察脉冲式添加氮源培养对耐温微藻Desmodesmus sp.F51细胞生长和细胞组成的影响.结果表明,在脉冲式添加氮源培养过程中,藻株FSI的蛋白质含量由(560±16) mg/g降低至(456±17) mg/g,而碳水化合物和油脂含量则分别由(209±13) mg/g和(98±3) mg/g提高至(310±12) mg/g和(120±4) mg/g.另外,对色素和油脂的具体组成变化进行分析,发现脉冲式添加氮源培养可增强β-胡萝卜素的生物合成,以及促进α-胡萝卜素生物转化为叶黄素,同时还可发现叶黄素积累与多不饱和脂肪酸含量变化呈正相关性.而在碳水化合物的具体组成分析中,发现碳水化合物为藻株F51主要的储能物质,当脉冲式添加氮源培养时间为3d时,其葡萄糖占总碳水化合物的质量分数可明显提高至(75.7±1.4)％.采用脉冲式添加氮源培养策略可明显同时促进藻株F51叶黄素和碳水化合物的生产.
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