Investigation of autotrophic, heterotrophic, and mixotrophic modes of cultivation on lipid and biomass production in Chlorella vulgaris

Abstract

Background: The cultivation mode plays a great role in biomass production and composition in the green microalga Chlorella vulgaris. Aims and Objectives: The effects of three different cultivation modes including autotrophic, heterotrophic, and mixotrophic growth conditions on the biomass and lipid production and also on the biomass composition in the unicellular photosynthetic microalga C. vulgaris were investigated. Materials and Methods: BG-11 culture medium was used for preservation and analysis of the studied microalgal strain. Effects of three different cultivation strategies including autotrophic, heterotrophic, and mixotrophic modes of cultivation were investigated on biomass and lipid production in C. vulgaris. Results: The maximum amount of cell dry weight was obtained in mixotrophic mode (3.91 g L−1) while autotrophic and heterotrophic modes achieved a final cell dry weight of 2.47 g L−1 and 1.52 g L−1, respectively. Besides, the biomass production in mixotrophic was increased 158% and 257% in 21 days, compared with autotrophic and heterotrophic conditions. The heterotrophic cultivation mode achieved the highest lipid contents (48.68%) which was 110.01% and 143.13% times higher than the mixotrophic (44.25%) and autotrophic (34.01%) conditions. The protein accumulation in autotrophic mode with 41.7% had the highest value. Conclusion: Considering the biomass produced in mixotrophic condition in the studied microalgal strain, this cultivation mode is recommended for lipid production which can be used for green energy production.