Sustainable and optimized bioethanol production using mix microbial consortium of Saccharomyces cerevisiae and Candida cantarelli

[Display omitted] •Herein, sustainable transformation of agro-waste into high-value fuel is reported.•Bioethanol was produced using mix microbial consortium of S. cerevisiae and C. cantarelli.•Three factor Box Behnken Design and regression analysis was employed for optimum ethanol yield.•Up to 92.5 g/L ethanol yield was obtained after 6 h fermentation using mix microbial consortium. Agro-industrial wastes, the most abundant, readily available, and economical materials are of supreme interest that supports sustainable transformation into high-value fuels. However, the low productivity of ethanol due to the inhibition from the degradation product is a significant concern. In the present study, this limitation has been overcome by fermentation of pre-treated saccharified corn stover (CS) with co-cultures of locally isolated and identified strains, i.e., Saccharomyces cerevisiae (FBL-01) and Candida cantarelli (FBL-01). Three factor Box Behnken Design (BBD) and regression analysis was employed for optimum yield of ethanol. The lignin content in residual solids was decreased to 3.95%, although 91.28% of lignin was decomposed in CS after pre-treatment with 1% (w/v) NaOH. HPLC analysis revealed that concentration of reducing sugars; mannose 21.7 g, fructose 15.08 g, glucose 24.5 g were present in saccharified CS whereas activities of β-glucosidase, endo-glucanase, and exo-glucanase were 46.8 ± 1.43, 53.5 ± 1.24 and 41.3 ± 1.31 U/mL, respectively. SEM analysis confirmed that every step, i.e., pre-treatment, saccharification, fermentation decreased crystallinity, and degree of polymerization of CS. After 6 h fermentation using 3:2 mL (S. cerevisae: C. cantarelli) inoculum size ratio at pH 6 and 35 °C, up to 92.5 g/L ethanol yield was obtained. The present study suggested that bioethanol production could be effectively enhanced by co-cultures of yeast using BBD from corn stover.