Effect of Photoperiod and Glycerol Supplementation on the Biomass Productivity and Protein Production of Spirulina sp. LEB 18 Cultures

Changes in nutritional and lighting conditions to obtain compounds of interest and biomass via microalgal cultures are among the main foci of studies in algal biotechnology. Growth medium supplementation using organic compounds, such as glycerol, is a promising approach for increasing biomass productivity and the viability of microalgal cultivation and adding value to byproducts of the biodiesel industry. In this study, the influence of crude glycerol on Spirulina sp. LEB 18 was investigated via culturing using different photoperiods, and its effect on biomass composition and cell growth was evaluated. The microalgae were subjected to three photoperiods (continuous light, 24:0; 12 h light and 12 h dark, 12:12; and no illumination, 0:24) and crude glycerol supplementation (2.5 g L−1); better productivity and biomass concentrations were obtained in cultures with a 12:12 photoperiod (28.36 mg L−1 h−1 and 1.24 g L−1, respectively). Under this condition, the highest protein yield was achieved (647.3 mg L−1, 52.2% w w−1), and the obtained biomass showed favorable characteristics for applications in animal feed enrichment.