Enhanced ethanol production from stalk juice of sweet sorghum by response surface methodology

Abstract

Sweet sorghum (sugar sorghum, Sorghum bicolor) is one kind of non-grain energy crops. As a novel green regenerated high-energy crop with high utility value, high yield of biomass, the sweet sorghum is widely used and developed in China. Stalk juice of sweet sorghum was used as the main substrate for ethanol production by a Saccharomyces cerevisiae strain because of the high content of sugar. Effects of different medium compositions, including urea, KH₂PO₄ and MgSO₄, on ethanol production were studied by response surface methodology in this paper. A second-order model that related the concentration of ethanol was developed and thus the optimal medium composition was obtained, which was 4.75 g l^-1 urea, 3.58 g l^-1 KH₂PO₄, and 0.98 g l^-1 MgSO₄. Under this condition, the highest ethanol concentration reached 86.2 g l^-1.

Key words: Ethanol, sweet sorghum, stalk juice, medium composition, response surface methodology.