Unexpected high production of biohydrogen from the endogenous fermentation of grape must deposits

The aim of this work was to assess the performances wine byproduct biomass for hydrogen production by dark fermentation. Grape must deposits from two grape varieties (Pinot Gris and Chardonnay) were considered, either with external microbial inoculum or without. We show that residues contain endogenous microflora, well adapted their environment, which can degrade sugars (initially contained in biomass) without any nutrient addition. Indeed, during fermentation is as efficient an heat-treated (2.5 ± 0.4 LH2.L−1reactor 1.61 0.41 molH2.mol−1consumed hexose, respectively) a lower energy cost. Hydrogen-producing bacteria selected microflora semi-batch bioreactor operation, shown T-RFLP profiles 16S rRNA sequencing, Clostridium spp. (butyricum, beijerinckii, diolis, roseum) identified major phylotype. Such efficiency opens new perspectives innovating valorization winery by-products.