Microalgae (Nannochloropsis salina) biomass to lactic acid and lipid

A method for lactic acid production and lipid extraction from microalgae (Nannochloropsis salina) biomass was investigated. Microalgae biomass was acid (5% H2SO4) hydrolyzed at 120 °C for 1 h, and subsequently treated with hexane at 40 °C and 200 rpm to separate lipid from the hydrolysate. The sugar (glucose plus xylose) yield reached 64.3% and remained the same until the biomass loading of 15% (w/v) after which, it dropped. Lipid free hydrolysate was neutralized and used as fermentation medium for Lactobacillus pentosus for lactic acid production. Lactic acid yield reached 92.8% at sugar 3–25 g/l, 30 °C and shaking speed 150 rpm under anaerobic condition. The acid hydrolysis facilitated lipid extraction from microalgae biomass, and lipid yields with and without acid hydrolysis were 85.6% and 48.7%, respectively. Results suggest that the developed method can be successfully applied in lipid extraction and lactic acid production from microalgae biomass.

► A method for lipid extraction and lactic acid production from microalgae biomass.
► The method gave 1.75-fold higher lipid yield.
► The microalgae biomass hydrolysate, a nutrients source for L. pentosus.
► Lactic acid yield reached 92.8%.