Produção de biomassa de Saccharomyces cerevisiae em meios de cultivo à base de melaço de cana-de-açúcar: avaliação de regimes de alimentação e aeração

Abstract

The growing demand for sustainable alternatives for the valorization of agro-industrial by- products has stimulated the development of biotechnological processes aimed at microbial biomass production. In this context, sugarcane molasses stands out as a low-cost and widely available carbon source that can be employed for yeast cultivation, generating biomass with potential applications in animal nutrition. The present study evaluated biomass production by industrial strains of Saccharomyces cerevisiae cultivated on commercial sucrose and sugarcane molasses, with emphasis on the effects of different operational strategies on metabolic regulation and substrate-to-biomass conversion efficiency. Initially, a physiological screening of five industrial strains (Y904, PE-2, PhibroADY, Ethanol Red, and FT858) was performed in batch cultures, leading to the selection of strain FT858 for subsequent experiments. Cultivations were then carried out in a bench-scale bioreactor under different feeding regimes, aeration conditions, and oxygen supply conditions. The results demonstrated that oxygen availability was the most influential factor affecting the physiological performance of the selected strain. Replacing compressed air with pure oxygen increased biomass yield by 301%, from 0.069 to 0.277 g·g−1. In cultures conducted with sugarcane molasses using pure oxygen, increasing the aeration from 0.5 to 1.67 vvm improved biomass yield from 0.157 to 0.255 g·g−1 while reducing ethanol formation. Conversely, fed-batch strategies that promoted residual sugar accumulation intensified the Crabtree effect, decreasing the efficiency of substrate conversion into biomass. Under the selected cultivation conditions, the biomass exhibited a crude protein content of 40.5 ± 1.9% on a dry-weight basis, highlighting its potential for application in animal feed formulations. Overall, the findings demonstrate that the simultaneous control of carbon availability and oxygen supply is essential to maximize biomass production by strain FT858 when cultivated on sugarcane-derived substrates.