Ethanol production from Agave tequilana leaves powder by Saccharomyces cerevisiae yeast applying enzymatic saccharification without detoxification

Abstract

The replacement of fossil resources with renewable biomass in a bioeconomy is seen as a major contribution to climate change mitigation. The transformation from a petrochemical-based economy to a bio-based economy necessitates the novel exploitation of cost-effective natural materials for both future biorefinery development and a range of value-added products of interest. The present investigation proposes the use of Agave tequilana Weber leaves, an agro-industrial residue with a huge potential to produce liquid biofuels. The objective of the present work is to evaluate the alcoholic fermentation by S. cerevisiae yeast in powdered A. tequilana leaves (dry-mill,100 °C, diameter ≤ 300 µm) pretreated with two enzymatic saccharification processes without detoxification and determine the highest yield bioconversion of sugars to ethanol. Alcoholic fermentation was evaluated using yeast at different times (0−42) h with an initial concentration of 34.06 ± 0.4 g/L reducing sugars. S. cerevisiae has the highest ethanol production 12.20 ± 0.3 g/L within 18 h obtained an ethanol yield of 0.41 g/g (81% of theoretical value), and volumetric ethanol productivity 0.68 ± 0.02 g/L/h. Yeast was able to consume the 86.4% reducing sugars and increase to 17.2-fold cell concentration in the presence of 80.30 ± 0.70 mg/L phenolic compounds. This biotransformation of waste has great potential and significant prospects for wider industrial and biotechnological applications, the results show the feasibility and efficiency to produce ethanol, is a clean source of energy and offers a solution for countries that produce agave or similar feedstocks. It is firmly believed by the author that, due to the large amounts of waste produced by the tequila industry, the best solution for this problem does not lie in this paper or implementation of a single treatment. On the contrary, a mix of some of the alternative treatments presented in other works would probably represent the most efficient option, from both an economic and environmental point of view.