Process optimization for the production of high-concentration ethanol with Scenedesmus raciborskii biomass.

Scenedesmus raciborskii WZKMT was subjected to fed-batch enzymatic hydrolysis and fermentation to facilitate the saccharification of high-solid-loading substrate for high-concentration ethanol. In this work, process factors affecting enzymatic hydrolysis, including enzyme loading, temperature, pH, and solid loading, were optimized. Results showed that 58.03 g L-1 glucose, 12.57 g L-1 xylose, and 1.45 g L-1 cellobiose were obtained after the enzymatic hydrolysis of 330 g L-1 substrates under the optimal conditions of 30 FPU g-1 enzyme loading, 50 °C, and pH 5.5. Meanwhile, 89.60% yield and 30.43 g L-1 content of ethanol were obtained after the fermentation of 330 g L-1 hydrolysate. The maximum ethanol concentration of 79.38 g L-1 could be achieved through repeated fed-batch process, indicating that S. raciborskii WZKMT is a promising feedstock for ethanol production.