Using an efficient fermenting yeast enhances ethanol production from unfiltered wheat bran hydrolysates.

Wheat bran, an abundant residue of the flour milling industry, is a promising feedstock for bioethanol production. The first objective of the present study was to define the optimised hydrolysis conditions for wheat bran that gave both high sugars concentration and little or no inhibitors formation. This low-cost material was subjected to acid treatment and then hydrolysed using increasing dosages of commercial enzymes. With the aim of selecting a robust yeast suitable for industrial ethanol production, new Saccharomyces cerevisiae yeasts were isolated. Among the strains having remarkable ethanol yields from glucose in a minimal broth with high sugars concentrations, S. cerevisiae MEL2 was selected to be used for wheat bran fermentation. The strain produced ethanol levels higher than the benchmark industrial yeast S. cerevisiae DSM70449, exhibiting an outstanding ethanol yield of 96% of the theoretical and also showing promising fermentative activity on the whole unfiltered hydrolysates. This study demonstrated that dilute acid pre-treatment and the use of a properly selected yeast had a great impact on the overall ethanol yield from wheat bran