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In the present study the non-conventional yeast Wickerhamomyces anomalus X19, was evaluated as biocatalyst for direct, low cost bioethanol production, using natural date palm sap (DPS) as substrate. Initial experiments were conducted with synthetic media in order to characterize the strain in terms of its nitrogen requirements, the effect of initial substrate concentration on the ethanol yields and the main kinetic constants during alcoholic fermentation. Subsequently, the effect of aerobic or anaerobic conditions was assessed with DPS as substrate, in batch mode and the possible improvement of ethanol yields was further investigated via fed batch experiments. It was shown that W. anomalus X19 was not inhibited by low pH (<3) and high initial sugar concentrations (up to 160 g/L), leading in all cases to ethanol yields that exceeded 80% of the theoretically estimated values. The highest ethanol concentration from DPS fermentation was achieved in fed batch experiments, reaching 73.11 g/L and the ethanol yield was 0.46 g/g sugars, which corresponded to more than 90% of the theoretical maximum. • Date palm sap was assessed as renewable EtOH production feedstock via W. anomalus. • Batch and fed batch fermentations reached to high yields without pH adjustment. • EtOH max at fed-batch mode exceeded 73 g/L leading to 91% fermentation efficiency. [ABSTRACT FROM AUTHOR]

• The potential use of potato peels waste for bioethanol production was tested. • A newly isolated strain of W. anomalus was used for ethanol production. • Different methods were tested for saccharification. • The possibility of using lab-scale produced enzymes was also explored. • Different process schemes were evaluated for fermentation. The present study focuses on the exploration of the potential use of potato peels waste (PPW) as feedstock for bioethanol production, using a newly isolated yeast strain, Wickerhamomyces anomalus, via different saccharification and fermentation schemes. The saccharification of PPW was performed via thermal and chemical (acid, alkali) pretreatment, as well as via enzymatic hydrolysis through the use of commercial enzymes (cellulase and amylase) or enzymes produced at lab scale (alpha-amylase from Bacillus sp. Gb67), either separately or in mixtures. The results indicated that the enzymatic treatment by commercial enzymes led to a higher saccharification efficiency (72.38%) and ethanol yield (0.49 g/g consumed sugars) corresponding to 96% of the maximum theoretical. In addition, acid pretreatment was found to be beneficial for the process, leading also to high hydrolysis and ethanol yields, indicating that PPW is a very promising feedstock for bio-ethanol production by W. anomalus under different process schemes. [ABSTRACT FROM AUTHOR]