Effects of Trophic Modes on the Lipid Accumulation of Parachlorella kessleri TY

Abstract

Microalgae are considered to have great potential as a source of biodiesel. Currently, algae culture has three different trophic modes, i.e., autotrophic, heterotrophic, and mixotrophic, but not all kinds of algae are suitable for heterotrophic and mixotrophic cultivation. In this study, Parachlorella kessleri TY, screened from the soil of Shanxi Province, was heterotrophically and mixotrophically treated with glucose as an organic carbon source, and the physiological and biochemical levels of its growth and lipid accumulation were measured. The results showed that the highest biomass and biomass productivity (1.53 g·L−1 and 218.57 mg·L−1d−1) were attained by P. kessleri TY under mixotrophic cultivation. In comparison, the lowest (0.55 g·L−1 and 78.57 mg·L−1d−1) were attained under heterotrophic culture. Furthermore, heterotrophic and mixotrophic conditions could accumulate more lipids (total lipid contents: 39.85% and 42.92%, respectively), especially the neutral lipids. Additionally, the contents of fatty acids suitable for use as biodiesel raw materials in both heterotrophic and mixotrophic cultures increased, especially the content of C18:1. Moreover, due to the lower biomass of heterotrophic cultivation compared with that from mixotrophic cultivation, the total lipid productivity of heterotrophic conditions decreased. In summary, the conditions of mixotrophic cultivation are more conducive to the accumulation of lipids in P. kessleri TY.