초록
We investigated the conversion of hexoses and pentoses liberated from high osmotic pressure soybean hull hydrolysate (SHH) into ethanol by immobilized Saccharomyces cerevisiae, Candida shehatae, and Spathaspora arborariae, or their co-cultivations. Soybean hull was hydrolysed in a two-steps sulphuric acid-enzyme treatment using an enzymatic complex of Penicillium echinulatum S1M29, resulting in more than 72% of saccharification. In shaker cultivations, the bioconversion of SHH into ethanol showed yields (Y<SUB>P/S</SUB>) of 0.43, 0.47, and 0.38, in cultures of S. cerevisiae, C. shehatae, and S. arborariae, respectively. Co-cultures of S. cerevisiae and C. shehatae or S. cerevisiae and S. arborariae, produced Y<SUB>P/S</SUB> of 0.48 and 0.40, respectively. S. cerevisiae and C. shehatae were immobilized in Ca-alginate and cultivated in bioreactors to analyse the possibility of scaling up this process. Immobilized-cell cultures showed yields of 0.45 and 0.38, respectively. Results suggest the viability of acid-enzymatic saccharification of soybean hulls for second-generation ethanol production by immobilized yeast cells in bioreactors.