Avaliação do potencial biotecnológico de leveduras industriais

Abstract

Sacharomyces cerevisiae CAT-1 stands out as the strain with the highest fermentation capacity proven to date. However, S. cerevisiae FT858 was recently presented as a potential alcoholic fermenter. Thus, the aim of this work was to evaluate the physiology of S. cerevisiae FT858 in terms of substrate consumption, formation of extracellular metabolites, cell growth and invertase activity in different carbon sources to compare it with S. cerevisiae CAT-1. S. cerevisiae FT858 presented kinetic growth parameters very close to those obtained with S. cerevisiae CAT-1 under similar culture conditions (aerobiosis, temperature, agitation, substrate and concentration). However, there was a 10% increase in sucrose yield into ethanol obtained with S. cerevisiae FT858 when compared to S. cerevisiae CAT-1 at 37 °C. The concentration of the substrates directly interfered in the production of invertase for both S. cerevisiae FT858 and CAT-1. The enzymatic expression underwent strong regulation through the concentration of glucose in the culture medium. However, only S. cerevisiae CAT-1 showed a constitutive behavior for the enzyme invertase. In a second study, a total of 14 yeast strains, including S. cerevisiae CAT-1, were also evaluated in terms of kinetic parameters and compared. In general, yeasts of the genus Kluyveromyces showed greater respiratory potential while yeasts of the genus Saccharomyces had a greater fermentative capacity. Among other results, it is noteworthy that Kluyveromyces marxianus NRRLy 2415 was the largest producer of biomass (23.17 ± 0.000 C-X), while S. cerevisiae BG-1 was the smallest producer (3.05 ± 0.000 C-X).