高碳低氮条件下培养基中磷水平对莱茵衣藻生长及油脂合成的影响Effect of phosphorus level in culture medium on the growth and oil synthesis of Chlamydomonas reinhardtii under high carbon and low nitrogen conditions

Abstract

为进一步提高莱茵衣藻的生物量和油脂含量，在前期已明确最佳碳氮水平的基础上，通过分析不同磷水平下莱茵衣藻生物量、油脂含量、叶绿素a和叶绿素b含量、油脂脂肪酸组成及含量、可溶性糖含量、可溶性蛋白含量等指标的变化，探究高碳低氮条件下培养基中磷水平（0P、1/8P、1/4P、 2/4P、4/4P、5/4P）对该藻生长及油脂积累的影响。结果表明：随着培养基中磷水平的增加，莱茵衣藻生物量、油脂含量和油脂产率呈先增加后降低的趋势，培养5 d，磷水平1/8P时的生物量、油脂含量和油脂产率最高，分别为2.27 g/L、43.35%和191.31 mg/（L·d)，分别比0P时提高9155%、13.09%和123倍；培养5 d，磷水平5/4P时叶绿素a和叶绿素b含量最高，分别达到515 mg/L和3.46 mg/L，分别比0P时高230倍和0.65倍;当磷水平为1/8P～5/4P时，莱茵衣藻油中各脂肪酸含量总体差异不显著，但其多不饱和脂肪酸含量均显著低于0P时的，饱和脂肪酸和单不饱和脂肪酸含量则显著高于0P时的；随培养基中磷水平的增加，可溶性糖含量呈上升趋势，而可溶性蛋白含量呈降低趋势。综上，在高碳低氮条件下，与常规磷水平培养基培养相比，适当降低培养基中磷水平可进一步提高莱茵衣藻的生物量和油脂含量，同时获得较高的可溶性糖和可溶性蛋白含量。To further increase the biomass and oil content of Chlamydomonas reinhardtii, based on the optimized carbon and nitrogen levels in previous research, the effects of various phosphorus(P) levels(0P, 1/8P, 1/4P, 2/4P, 4/4P, 5/4P) on the growth and oil accumulation were investigated under high carbon and low nitrogen conditions by analyzing the changes of biomass, oil content, fatty acid composition and content of oil, chlorophyll a and chlorophyll b contents, as well as soluble sugar and soluble protein contents. The results showed that the biomass, oil content and oil productivity of C. reinhardtii tended to increase and then decrease with the increase of P levels. The algal cells cultured for 5 d under 1/8P treatment displayed the highest biomass, oil content, and oil productivity of 2.27 g/L, 43.35%, and 191.31 mg/(L·d), which improved by 91.55%, 1309%, and 1.23 times in contrast with the 0P treatment, respectively. The maximal contents of chlorophyll a and chlorophyll b were achieved at 5/4P, with values of 5.15 mg/L and 3.46 mg/L, respectively. These values were 230 times and 0.65 times higher than those of 0P, respectively. When P levels ranged from 1/8P to 5/4P, the differences in the percentage of each fatty acid in the oil of C. reinhardtii were non-significant, but polyunsaturated fatty acid content were remarkably lower than those of the cultures grown in the 0P substrate. Meanwhile, the content of saturated and monounsaturated fatty acids were obviously higher than those in the 0P treatment. In addition, the increase in P levels was accompanied by a marked enhancement in soluble sugar content, while soluble protein levels declined. In conclusion, under high carbon and low nitrogen conditions, the biomass and oil content of C. reinhardtii can be further increased by reasonably lowering the P level in the medium compared with the cultured cells in the conventional P levels, simultaneously obtaining higher soluble sugar and soluble protein contents.

Keywords

• 莱茵衣藻；磷水平；微藻生物量；油脂；脂肪酸组成
• chlamydomonas reinhardtii; phosphorus level; microalgal biomass; oil; fatty acid composition