Ethanol Production from Seaweed, Enteromorpha intestinalis, by Separate Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF) with Saccharomyces cerevisiae

Abstract

Ethanol productions were performed by separate hydrolysis and fermentation (SHF) and simultaneous saccha-rification and fermentation (SSF) processes using seaweed, Enteromorpha intestinalis (sea lettuce). Pretreatment condi-tions were optimized by the performing thermal acid hydroly-sis and enzymatic hydrolysis for the increase of ethanol yield. The pretreatment by thermal acid hydrolysis was carried out with different sulfuric acid concentrations in the range of 25 mM to 75 mM H 2 SO 4 , pretreatment time from 30 to 90 min-utes and solid contents of seaweed powder in the range of 10~ 16% (w/v). Optimal pretreatment conditions were determined as 75 mM H 2 SO 4 and 13% (w/v) slurry at 121 o C for 60 min. For the further saccharification, enzymatic hydrolysis was per-formed by the addition of commercial enzymes, Celluclast 1.5 L and Viscozyme L, after the neutralization. A maximum reducing sugar concentration of 40.4 g/L was obtained with 73% of theoretical yield from total carbohydrate. The ethanol concentration of 8.6 g/L of SHF process and 7.6 g/L of SSF process were obtained by the yeast, Saccharomyces cerevisiae KCTC 1126, with the inoculation cell density of 0.2 g dcw/L.