Valorization of Macroalgal Hydrolysate for the Production of Lipids and DHA by Marine Microbes.

Abstract

The present study aimed to explore the potential of macroalgal hydrolysate to serve as an economical substrate for the growth of the oleaginous microbes Aspergillus sp. SY-70, Rhizopus arrhizus SY-71 and Aurantiochytrium sp. YB-05 for lipid and DHA production under laboratory conditions. The macroalgal hydrolysate was used at three concentrations 20, 40 and 80 g/L as a sole carbon source or in combination with 10 g/L of either acetic acid, glycerol, glucose, or sugarcane molasses. Glucose was used as a positive control at four different concentrations: 10, 20, 40, and 80 g/L. Out of the 19 carbon sources tested for the three microbes, 80 g/L macroalgae + 10 g/L molasses was the best source for Aspergillus sp. SY-70 (27.4 g/L DW and 9.73 g/L lipid) and R. arrhizus SY-71 (49.76 g/L DW and 16.88 g/L lipid), whereas 20 g/L macroalgae + 10 g/L glucose afforded the best source for Aurantiochytrium sp. YB-05 (27.93 g/L DW and 11.07 g/L lipid). Among the 19 carbon sources used for the growth of Aurantiochytrium sp. YB-05, we determined the fatty acid profile of the best four carbon sources that gave the highest biomass and lipid percentage. Among the four sources, 20 g/L macroalgal hydrolysate + glucose gave the highest DHA percentage (2.31 g/L), followed by 80 g/L pure glucose (1.68), 80 g/L macroalgal hydrolysate + glycerol (1.64), and 40 g/L macroalgal hydrolysate + molasses (1.52). The three carbon sources can replace pure glucose for the lipid, DPA, and DHA production using Aurantiochytrium sp. YB-05. The results of the current study suggest that we could use macroalgal hydrolysate in combination with molasses or glucose for the production of single-cell oil.