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

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 (qS), maximum specific growth rate (µmax), doubling time, biomass yield, product yield, maximum cell concentration, ethanol productivity (PEth), biomass productivity, and CO2 concentration. S. cerevisiae CAT-1 exhibited the highest values in glucose for µmax (0.35 h-1), qS (3.06 h-1), and PEth (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 µmax (0.25 h-1), qS (2.24 h-1), and PEth (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 PEth (0.72, 0.51, and 0.44 gEth L-1 h-1, respectively) compared to other carbon sources.

Physiology of yeast strains isolated from Brazilian biomes in a minimal medium using fructose as the sole carbon source reveals potential biotechnological applications.

The aim of this study was to evaluate the kinetic parameters and the production of metabolites of 13 novel yeasts isolated from a distillery and fruits, and Saccharomyces cerevisiae CAT-1, cultivated in fructose-based medium. The yeasts with the highest µ max were obtained from must, Pichia kudriavzevii BB2, P. kudriavzevii BB1, and S. cerevisiae BB9 (0.47-0.49 h-1). S. cerevisiae CAT-1 (3.02 g gDCM-1 h-1), S. cerevisiae BB9 (3.01 g gDCM-1 h-1), and Candida glabrata Recol 41 (2.52 g gDCM-1 h-1) stood out in terms of µ S. C. parapsilosis Recol 29, and Rhodotorula mucilaginosa Recol 03 strains showed the highest Y X/S (0.30 and 0.28 gDCM g-1, respectively). C. glabrata Recol 10 and S. cerevisiae BB9 strains stood out for their higher substrate conversion rates into ethanol (0.44 and 0.41 gEth gS-1, respectively). R. mucilaginosa Recol 03 presented the poorest performance in substrate consumption (0.87 g gDCM-1 h-1), while the strains isolated from must and C. glabrata Recol 10 showed the highest ethanol production and the C. parapsilosis Recol 29 showed the highest biomass conversion.