ethanol production from saccharina japonica using an optimized extremely low acid pretreatment followed by simultaneous saccharification and fermentation

an extremely low acid (ela) pretreatment using 0.06% (w/w) sulfuric acid at 170 °c for 15 min was employed to extract non-glucan components from saccharina japonica, a brown macroalgae. subsequent simultaneous saccharification and fermentation (ssf) was conducted using saccharomyces cerevisiae dk 410362 and cellulase (15 fpu/g-glucan) and ß-glucosidase (70 pnpgu/g-glucan). deionized water was used for making fermentation suspension. after the ela pretreatment, a glucan content of 29.10% and an enzymatic digestibility of 83.96% was obtained for pretreated s. japonica. these values are 4.2- and 2.4-fold higher, respectively, than those of obtained with untreated s. japonica. in ssf, a bioethanol concentration of 6.65 g/l was obtained, corresponding to a glucose equivalent concentration of 13.01 g/l, which indicated an ssf yield of 67.41% based on the total available glucan of the pretreated s. japonica. the remaining separated liquid hydrolysate, which contains mannitol and alginate-derived oligosaccharides can be applied to other fermentations.