Yeast-filamentous fungi co-culture: A circular bioeconomy approach for distillation stillage treatment and revalorization

Abstract

Tequila vinasses are a waste generated during tequila production, common among all distilled products, that causes environmental issues such as eutrophication and soil toxicity. To promote the sustainable management of tequila industry waste, this study proposes a systems-based approach centered on the bioconversion of vinasse using microbial consortia. The objective is to develop a process that, besides mitigating environmental impact, generates a high-nutritional value byproduct for animal feed, thereby closing the production cycle and fostering a circular economy in the region. This study conducted various aerobic treatments in both mono-cultures and co-cultures, using six different strains: C. utilis, R. mucilaginosa, K. marxianus, A. niger, A. oryzae, and R. oligosporus or contaminant removal while developing added value products such as high-protein biomass production and contaminant removal. The C. utilis and A. oryzae co-culture showed the best results at the tube-scale cultures and was subsequently scaled up along with the respective mono-cultures. Kinetic studies over 72 h demonstrated removal efficiencies of up to 63.52 % for TN, 86.87 % for P, 46.21 % for COD, and −1.46 % increase in total phenols concentration. Co-culture biomass quantity at steady state was modeled using the biphasic Zwietering-modified Gompertz model, with ${\mu }_{\max 1}$ = 0.0758 and ${\mu }_{\max 2}$ = 0.0827, reaching 4.25 g L⁻¹ after 150 h. Biomass achieves a high-value protein content of 47.27 g kg⁻¹.