Orange waste as a biomass for 2G-ethanol production using low cost enzymes and co-culture fermentation

The successful conversion of orange waste into a mixture of fermentable sugars was achieved using low cost enzymes obtained from the citrus-canker bacterium Xanthomonas axonopodis pv. citri strain 306 (IBSBF 1594). Then, fermentable sugars were converted into 2G-ethanol using Saccharomyces cerevisiae in combination with one of the two isolated yeast strains, Candida parapsilosis strains IFM 48375 and NRRL Y-12969 (ATCC 2219), in independent submerged co-culture fermentations. The co-culture fermentations enabled reducing fermentation time to 6 h. Pure ethanol in excellent yield with C-6 sugars conversion of 98.9% was obtained. Therefore, diminished costs of enzyme biomass processing and reduced fermentation time could make the 2G-ethanol production from orange waste even more feasible, cost-effective and an environmentally friendly process.