Mixotrophic cultivation of Chromochloris zofingiensis on glycerol, acetate, and vinasse

This study investigated the mixotrophic cultivation of the green microalga Chromochloris zofingiensis on glycerol, acetate, and vinasse, as low-cost substrates. The alga was cultivated on different concentrations of glycerol (0.5-8 g L-1), sodium acetate (0.01-1 g L-1), and vinasse (0.12-3.6 g L-1) (the green stages) in the presence of either air (0.04% CO2) or enriched air (2% CO2). Subsequently, the cells were subjected to stress (simultaneous high light intensity and nitrogen starvation, red stage). The final biomass concentrations and composition achieved at the end of green stages as well as the biochemical composition of biomass, the total carotenoid, astaxanthin, and canthaxanthin contents at the end of red stages were elucidated. Glycerol and acetate concentrations higher than 2 and 0.1 g L-1, respectively, did not enhance the final biomass concentration and vinasse concentrations higher than 1.2 g L-1 led to a reduction in final biomass concentration. Hence, the optimum concentrations of glycerol, acetate, and vinasse were found to be 2, 0.1, and 1.2 g L-1, respectively. Moreover, the application of stress on cells resulted in higher lipid and carbohydrate contents and increased dry weight. However, there was no significant difference in carotenoid, astaxanthin, and canthaxanthin contents of biomass among all cultivations. Therefore, cultivation on 1.2 g L-1 vinasse is proposed as a potential method for the production of carotenoid-rich cells of C. zofingiensis due to the ease of medium preparation (the medium contained only vinasse) and lower cost medium compared to Bold's Basal Medium.

Automated summary

This study found that the optimal cultivation concentrations for glycerol, acetate, and vinasse were 2, 0.1, and 1.2 g L-1, respectively. Applying stress to cells resulted in increased lipid and carbohydrate contents, but did not significantly affect carotenoid, astaxanthin, and canthaxanthin contents. Cultivation on 1.2 g L-1 vinasse is proposed as a potential method for producing carotenoid-rich cells of C. zofingiensis due to its ease of medium preparation and lower cost compared to traditional medium.