Physiological evaluation of yeast strains under anaerobic conditions using glucose, fructose, or sucrose as the carbon source

Abstract

The aim of this study was to evaluate the physiology of 13 yeast strains by assessing their kinetic parameters under anaerobic conditions. They included Saccharomyces cerevisiae CAT-1 and 12 isolated yeasts from different regions in Brazil. The study aimed to enhance understanding of the metabolism of these strains for more effective applications. Measurements included quantification of sugars, ethanol, glycerol, and organic acids. Various kinetic parameters were analyzed, such as specific substrate utilization rate (q_S), maximum specific growth rate (μ_max), doubling time, biomass yield, product yield, maximum cell concentration, ethanol productivity (P_Eth), biomass productivity, and CO₂ concentration. S. cerevisiae CAT-1 exhibited the highest values in glucose for μ_max (0.35 h⁻¹), q_S (3.06 h⁻¹), and P_Eth (0.69 gEth L⁻¹ h⁻¹). Candida parapsilosis Recol 37 did not fully consume the substrate. In fructose, S. cerevisiae CAT-1 stood out with higher values for μ_max (0.25 h⁻¹), q_S (2.24 h⁻¹), and P_Eth (0.60 gEth L⁻¹ h⁻¹). Meyerozyma guilliermondii Recol 09 and C. parapsilosis Recol 37 had prolonged fermentation times and residual substrate. In sucrose, only S. cerevisiae CAT-1, S. cerevisiae BB9, and Pichia kudriavzevii Recol 39 consumed all the substrate, displaying higher P_Eth (0.72, 0.51, and 0.44 gEth L⁻¹ h⁻¹, respectively) compared to other carbon sources.