Integral valorization of vine shoots: Production of xylitol, butanol and 2,3-butanediol in a biorefinery context

Abstract

Vine shoots, a carbohydrate-rich lignocellulosic residue, represent a promising feedstock for producing xylitol, butanol, and 2,3-butanediol (2,3-BDO) in an integrated biorefinery. In this work, dilute sulfuric acid steam explosion (190 ◦C, 5 min, 1.6% w/v H2SO4) was used for the pretreatment of vine shoots. Xylitol was subse- quently produced from the vine shoots hemicellulosic hydrolysate using C. boidinii and C. guilliermondii; while butanol and 2,3-BDO were generated from the remaining solid fraction of vine shoots using C. beijerinckii and P. polymyxa, respectively. Furthermore, two process configurations for butanol and 2,3-BDO generation were evaluated: separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF), with comparisons conducted at high solids loadings (10% and 15% w/v). As a result, 8.4 g/L xylitol were achieved from the hemicellulosic fraction with C. boidinii. From the cellulosic fraction, the SHF configuration at the highest solids loading (15% w/v) yielded 8.8 g/L of butanol (corresponding to 12.4 g/L of total ABE) and 13.8 g/L of 2,3-BDO. Therefore, these results demonstrate the potential of vine shoots as a versatile feedstock for an integrated biorefinery