Avaliação dos parâmetros cinéticos de Saccharomyces cerevisiae CAT-1 e de 4 leveduras isoladas da região centro-oeste em diferentes substratos como fonte única de carbono em anaerobiose

Abstract

The objective of the work was to compare the physiology of the industrial yeast Saccharomyces cerevisiae CAT-1 with 4 strains of yeasts isolated from the Midwest region as the kinetic parameters and formation of metabolites obtained in cultivation with different sugars as sole carbon under anaerobic conditions. The strains were grown in sterile mineral medium, pH 6.0 and carbon source (10 g L-1), incubated at 30°C with continuous injection of nitrogen gas (N2). The cultivation flasks were connected with a second flask with sodium hydroxide (2M NaOH), which was used for carbon dioxide (CO2) analysis. Sugars, ethanol, glycerol and acetate were separated by ultra performance liquid chromatography (UPLC). The kinetic parameters measured were substrate is specific consumption rate (μS), maximum specific growth rate (μmax), doubling time (DT), cell substrate conversion factor (YX/S), substrate conversion products rate (YP/S) (ethanol, glycerol and acetate) and maximum concentration of cells formed (Xmax), in addition to ethanol productivity (PEth), biomass productivity (PX) and CO2 concentration. As results, Candida parapsilosis Recol 37 was the only isolated strain that did not efficiently grow (the higher μmax obtained was 0.09 h-1) on the substrates studied. C. glabrata Recol 43 was distinguished from other isolates in glucose and fructose cultivations (PEth = 0.57 e 0.54 gEth.L-1.h-1, respectively), showing good adaptation to these substrates. However, in sucrose cultivation it was not able to develop. In this condition only the Saccharomyces cerevisiae CAT-1 and BB9 were able to adapt.