Green juice was obtained by grinding a second cut of early bloom Canadian alfalfa (Medicago sativa) for 5 min and by pressing it using a laboratory hydraulic press at pressure conditions comprised between 4 and 6 MPa for 2 min. Its physiochemical characterization reveals a sugar content of 4.60 g/L, a nitrogen content of 3.16 g/L and 2.00 g/L of phenolic compounds (Mechmech et al., 2015b). Hardwood hemicellulosic pre-hydrolysate obtained from a dissolving pulp mill was subjected to acid hydrolysis with sulfuric acid at 1.5% wt/wt, to convert the oligomeric sugars into monomers,
and then detoxified by flocculation using ferric sulfate with a final sugars concentration of 26.7 g/L (Mechmech et al., 2015a). Clostridium acetobutylicum ATCC 824 was obtained from the American Type Culture Collection (ATCC) and inoculum preparation was carried out as described previously by Mechmech et al.
(2015b).