Effect of Carbon Sources and Fe<sup>3+</sup> on the Growth and Lipid Accumulation of <i>Monoraphidium</i> sp. FXY-10 under Mixotrophic Culture Condition

Abstract

Effects of different carbon source and Fe3+ for the growth and lipid accumulation of Monoraphidium sp. FXY-10 cultured mixotrophically was studied in our present work. The final cell density was reached to 2.626 g L-1 when glucose was the only carbon source, which is 1.43-fold to sodium acetate (1.834 g L-1), far higher than sucrose (0.251 g L-1) and xylitol (0.471 g L-1), but barely grow in other culture condition. Additionally, the highest algae lipid productivity (77.45 mg L-1 d-1) was obtained in 10 g L-1 glucose group, which indicated that glucose was the optimal carbon source for growth and lipid accumulation of Monoraphidium sp. FXY-10. Nevertheless, Monoraphidium sp. FXY-10 was grew slowly in BG-11 culture medium with the absence of Fe3+. The biomass was achieved at the top with 50μM Fe3+ added. With the increase of Fe3+ concentration, it showed no variation in the growth of microalgae. The highest biomass productivity (209.87 mg L-1 d-1) was reached when the Fe3+ concentration was at 150μM while highest lipid productivity (94.05 mg L-1 d-1) reached at 50μM, which indicated that Fe3+ was one of the most indispensable trace elements for the growth and lipid accumulation of Monoraphidium sp. FXY-10.