Mobilization of endogenous glycogen and trehalose of industrial yeasts

Abstract

The fermentation of yeast reserve carbohydrates, glycogen and trehalose is a procedure to increase protein level of yeast cells and improve ethanol production. This work studied on the degradation kinetics of glycogen and trehalose carried out with two industrial strains of Saccharomyces cerevisiae (PE-2 and SA-1) and the effect of different temperatures (38º, 40º, 42º and 44ºC) on degradation rate. Endogenous fermentation was carried out in a yeast suspension at 20% (w/v) based on wet weight, suspended in fermented media with 3.0 to 4.5 % (v/v) of ethanol. The degradation of the carbohydrate reserves at 40ºC followed first-order kinetics, showing that its rate is mainly dependent on the carbohydrate concentration in the cell. The degradation rate (k) ranged from 0.0387 to 0.0746 h -1 . Analyzing other parameters at 40ºC, it was observed that viability and dry and wet yeast biomass were reduced while cell protein, ethanol, glycerol and nitrogen in the medium increased. Glycogen and trehalose degradation at different temperatures (38º, 40º, 42º e 44ºC) showed that at 38ºC the degradation rate was slow and from 42ºC on the degradation of glycogen stopped after few hours of incubation. Thus, from a practical point of view, the best incubation temperature is around 40ºC. The application of the Arrhenius equation showed that activation energy from 40º to 42ºC was 165.90 and 107.94 kcal. o K -1 .mol -1 for trehalose and glycogen respectively for PE-2 strain, and 190.64 and 149.87 kcal. o K -1 .mol -1 respectively for SA-1 strain.

Ethanol production in Brazil: a bridge between science and industry

“…Trehalose and glycogen are reserve carbohydrates for additional energy when cells are starved for sugars 44, 45. Moreover, trehalose is a protecting compound to membrane that helps cells to tolerate dehydration and high ethanol concentrations as well as other industrial stressing factors 46, 47.…”

Very High Gravity Bioethanol Revisited: Main Challenges and Advances

“…Furthermore, these isolates showed to accumulate superior concentrations of trehalose, glycogen, and sterols when compared to the laboratory strains, which may explain the superior stress tolerance and fermentation performance. Trehalose and glycogen are energy reserve carbohydrates used by cells under sugar starvation conditions [27,28]. On a recent chemostat study, it was observed that the accumulations of trehalose and glycogen were strongly dependent of the cultivation temperature, with the highest glycogen accumulation at 12 • C and the highest trehalose accumulation at 39 • C [29].…”

Avaliação de condições operacionais na fermentação alcoólica VHG empregando diferentes cepas de Saccharomyces cerevisiae

“…Trealose e glicogênio são carboidratos de reserva para energia adicional quando as células estão famintas por açúcares (FERREIRA et al, 1999;PAULILLO et al, 2003). Além disso, a trealose é um composto protetor da membrana que ajuda as células a tolerar a desidratação e altas concentrações de etanol, bem como outros fatores estressantes industriais (PANEK et al, 1990;D'AMORE et al, 1991 horas com uma taxa de alimentação de 40 g de açúcar por hora proporcionou a maior eficiência de produção de etanol.…”