Effect of phosphorus level in culture medium on the growth and oil synthesis of Chlamydomonas reinhardtii under high carbon and low nitrogen conditions
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.
万方数据
维普
