Open AccessDynamic 13 C‐tracer study of storage carbohydrate pools in aerobic glucose‐limited Saccharomyces cerevisiae confirms a rapid steady‐state turnover and fast mobilization during a modest stepup in the glucose uptake rate
Author(s) -
Aboka Fredrick O.,
Heijnen Joseph J.,
Van Winden Wouter A.
Publication year - 2009
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1111/j.1567-1364.2008.00465.x
Subject(s) - chemostat , glycogen , glycolysis , trehalose , biology , biochemistry , saccharomyces cerevisiae , dilution , steady state (chemistry) , flux (metallurgy) , carbohydrate , metabolism , biophysics , chemistry , yeast , bacteria , genetics , physics , organic chemistry , thermodynamics
In this research, two dynamic 13 C‐labeling experiments confirmed turnover and rapid mobilization of stored glycogen and trehalose in an aerobic glucose‐limited chemostat ( D =0.05 h −1 ) culture of Saccharomyces cerevisiae . In one experiment, the continuous feed to an aerobic glucose‐limited chemostat culture of S. cerevisiae was instantaneously switched from naturally labeled to fully 13 C labeled while maintaining the same feed rate before and after the switch. The dynamic replacements of naturally labeled intracellular glycolytic intermediates and CO 2 (in the off‐gas) with their 13 C‐labeled equivalents were measured. The data of this experiment suggest that the continuous turnover of glycogen and trehalose is substantial ( c . 1/3 of the glycolytic flux). The second experiment combined the medium switch with a shiftup in the glucose feeding rate (dilution rate shiftup from 0.05 to 0.10 h −1 ). This experiment triggered a strong but transient mobilization of storage carbon, that was channelled into glycolysis, causing a significant disruption in the dynamic labeling profile of glycolytic intermediates. The off‐gas measurements in the shiftup experiment confirmed a considerable transient influx of 12 C‐carbon into glycolysis after the combined medium switch and dilution rate shiftup. This study shows that for accurate in vivo kinetic interpretation of rapid pulse experiments, glycogen and trehalose metabolism must be taken into account.