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Abstract

Bioethanol production from ligno cellulosic biomass by Sachharomyces cerevisiae is a matter of great concern due to its inability to ferment xylose which is present in abundance in biomass. Saccharomyces cerevisiae has undoubtedly been the organism of choice for ethanol production owing to its robustness, ethanol tolerance, inhibitor tolerance but its inability to utilize xylose is a limiting factor for the overall efficiency of the process. Henceforth, we look forward to searching non-conventional strains that are capable of utilizing both glucose and xylose. We isolated two yeast strains from rotten apple-Meyerozyma and Lodderomyces, as were identified by ITS sequencing. Fermentation of mixed sugar substrate (2:1 Glucose: Xylose) was carried out for 96 hours. Both the microorganisms depleted glucose and more than 33% xylose was consumed within 24 h. Ethanol produced was 0.344 g g-1 and 0.327 g g-1 by Meyerozyma and Lodderomyces respectively with an efficiency of about 65%. Strains were tolerant to inhibitors like 5-hydroxymethyl furfural and furfural at concentrations commonly found in pre-treated hydrolysates. This is the first report elucidating the potential of Meyerozyma and Lodderomyces for mixed sugar utilization, thereby producing ethanol.

Keywords: Non-conventional; Mixed sugar; Fermentation process