Increase in biomass productivity and protein content of Spirulina sp. LEB 18 (Arthrospira) cultivated with crude glycerol

Glycerol is a byproduct of biodiesel production. Purified, this compound has several applications; however, in its crude form, its commercial value is limited. An alternative use of crude glycerol is its application as an organic carbon source in microalgal cultures. This study aimed to investigate the different concentrations in crude glycerol influence productivity, biomass concentration, and biomolecules content in cultures ofSpirulinasp. LEB 18. Microalga was cultured in media supplemented with different glycerol concentrations in Erlenmeyer bioreactors during 15 days. The best glycerol concentration was 2.5 g L-1, which led to the maximum biomass productivity (0.43 g Lday(-1)). Proteins were the largest component of the biomass (75.7% w w(-1), 2.5 g L(-1)glycerol) and could be used to obtain high-added-value compounds. Carbohydrates ranged from 7.0 (control) to 8.9% (1.5 g L-1) w w(-1). Chlorophyll was reduced up to 47% (9.14 mg g(-1)) in the assay using 5 g L(-1)of glycerol. The lipids produced in this condition (8.3% w w(-1), 2.5 g L(-1)glycerol) presented interesting properties for biodiesel production because of their high content of saturated fatty acids (260.56 mg g(-1), 2.5 g L(-1)glycerol). Microalgae culture with crude glycerol could aggregate value to a biodiesel co-product through biocompounds production making the biofuel production process more sustainable.

Automated summary

This study investigated the effects of different concentrations of crude glycerol on the productivity, biomass concentration, and biomolecules content of Spirulina sp. LEB 18 cultures. The results showed that a glycerol concentration of 2.5 g L-1 led to the highest biomass productivity, with proteins being the main component that could be used to obtain high-added-value compounds. Additionally, the cultivation of microalgae with crude glycerol could contribute to a more sustainable biodiesel production process.