Exploitation of spoilage dates as biomass for the production of bioethanol and polyhydroxyalkanoates
Fathia Madi, Ridha Hachicha, Jesus Enrique Rodriguez Gamero, Ameya Pankaj Gupte, Nicoletta Gronchi, Mansour Haddad, Lorenzo Favaro, Sergio Casella, Marina Basaglia
Abstract
The exploitation of agri-food wastes is of great importance for environmental and economic reasons. Date wastes are attractive biomasses that could be used as a carbon source for the growth of microorganisms to obtain added-value products. In this work, spoilage date syrup, containing 102.01 and 101.00 g/L of glucose and fructose, respectively, was assessed as a feedstock for the production of bioethanol and polyhydroxyalkanoates (PHAs) by Saccharomyces cerevisiae MEL2 and Cupriavidus necator DSM 545, respectively. The waste date syrup was first evaluated as a carbon source for microbial growth and resulted to sustain the growth of both strains. 47.95 g/l of ethanol, corresponding to the 93.52% of the theoretical yield, were obtained from the fermentation of date syrup by S. cerevisiae MEL2, here adopted as a proficient bioethanol yeast strain. Furthermore, C. necator DSM 545, a well-known PHAs-producer, was able to accumulate up to 79.20 % (w/w on dry mass) of PHAs. This study demonstrates that bioethanol and PHAs can be obtained from date wastes, contributing to developing cost-effective exploitation of these residues with economic and environmental advantages.