Use of sweet sorghum juice for lipid production by Schizochytrium limacinum SR21

Stalk juice from sweet sorghum grown in Southern Illinois, USA, was examined for lipid production through microalgal fermentation. Juice concentrations at 100%, 75%, 50%, and 25% led to different biomass, lipid, and docosahexaenoic acid (DHA) production by Schizochytrium limacinum SR21. Biomass dry weight as 9.4 g/l at 50% juice concentration was similar to that from pure glucose (10.9 g/l). But with a 73.4% lipid content, this dose resulted in higher lipid and DHA production than those from pure glucose. Major fatty acids in cells grown on juice were identical to those fed by other substrates. Among the three sugars - glucose, fructose, and sucrose in sorghum juice, only glucose was utilized for growth. Spent medium after algal removal may be further processed for white sugar production in a traditional way since sucrose content remained the same throughout the algal fermentation process. Algal cells or lipids harvested can be utilized as fish meal, human nutrition supplements, or for biodiesel purpose.