Fermentative lactic acid production from Sotol bagasse (Dasylirion spp.): Optimization of microwave-assisted biomass pre-treatment

The valorization of industrial byproducts is a crucial step towards sustainable production. Sotol bagasse, a lignocellulosic residue from Sotol spirit production, is a promising feedstock for biorefineries. This study aimed to optimize microwave-assisted pre-treatment of sotol bagasse biomass for fermentative lactic acid production using a microbial consortium from cow manure. Microwave irradiation was employed to hydrolyze the complex structure of the Sotol bagasse, releasing fermentable sugars. Notably, these pre-treatments were more selective than traditional acid hydrolysis, minimizing the formation of inhibitory compounds like hydroxymethylfurfural. Instead, microwave pre-treatments promoted levulinic acid formation through autohydrolysis driven by steam explosions, a valuable chemical platform for various industrial applications. The optimal microwave pre-treatment conditions that led to almost pure glucose attaining a 3 % w/w efficiency in converting lignocellulose to glucose resulted in a maximum lactic acid production of 9.6 g/L. This study demonstrates the potential of Sotol bagasse as a sustainable feedstock for lactic acid production, contributing to a more circular economy.