The Production of Second-generation Bioethanol from Lignocellulosic Biomass using Two Strains of Sacharomyces cerevisiae

Abstract

Concerns about first generation bioethanol's impact on the food chain and biodiversity have shifted research to second generation (2G) bioethanol technologies. The 2G-bioethanol is made from lignocellulosic biomass, which is more sustainable and does not harm food security or the environment. This production process uses non-food crops, food crop residues, wood or food wastes, such as wood chips, skins, or pulp from fruit pressing. The present study examines the bioethanol production potential of three lignocellulosic biomass residues: corn cob, corn husk, and corn stem, as well as their physiochemical and mineral composition before and after fermentation. Before fermentation, the corn waste samples were hydrolyzed into sugar monomer and the hydrolysate was fermented separately to produce bioethanol for five days at 282oC using two Saccharomyces cerevisiae strains: typed yeast ATCC 3585 and Baker's yeast ATCC 204508/S288c. At one-day intervals, the pH, simple sugar and ethanol production were measured. ANOVA was used to find significant differences between the investigated organisms. The results showed that Saccharomyces cerevisiae ATCC 35858 produces more ethanol than the other strain (20.25±0.63). Corn cob also produced more ethanol than stem and husk. During fermentation, the typed yeasts outperformed the Baker's yeast in pH, reducing sugar, and specific gravity. Average dry yeast cell mass (ADM) of Saccharomyces cerevisiae ATCC 35858 and Saccharomyces cerevisiae ATCC 204508/S288c were 1.82±0.07 and 1.98±0.03, respectively. According to proximate composition, fermentation lost over 50% of the corn waste's nutrients (ash), while recovering over 50% of the minerals (nitrogen, phosphorus, and potassium). The ability of the two Saccharomyces cerevisiae strains to produce bioethanol was not significantly different at p value ≤ 0.05.