Efficient bioethanol production from date palm (Phoenix dactylifera L.) sap by a newly isolated Saccharomyces cerevisiae X19G2

Abstract In this research, 54 newly isolated strains of yeast from various microhabitats were screened in order to explore their potential for bioethanol production through bioconversion of date palm sap (DPS), as a renewable raw material. The highest ethanol concentration of 58.7 ± 0.23 g/L was achieved by the newly selected Saccharomyces cerevisiae strain X19G2 under anaerobic conditions. The effects of nitrogen supplementation, inoculum size and incubation temperature on bioethanol production from DPS by this strain were investigated. Bioethanol yield (0.43 ± 0.01 g/g consumed sugars) and ethanol productivity (1.49 ± 0.11 g/L·h) increased significantly when a mixture of ammonium sulfate and yeast extract (1:1) were used as nitrogen sources at 30 °C. Subsequently, batch and fed-batch (FB) fermentation were performed in a 2 L bioreactor. The highest ethanol yield was achieved in the FB experiment, reaching 0.48 g/g consumed sugars, which corresponded to over 90 % of the maximum theoretical yield. Based on these findings, the minimum bioethanol production potential using DPS was estimated to be approximately 11000 L per hectare of palm trees. This study indicated that DPS is a highly promising feedstock for bioethanol production by the yeast S. cerevisiae strain X19G2 with economic benefits for industrial scale production.