Evolutionary scenario for the origin of Crabtree effect in <i>Saccharomycetales</i> yeast.

<p>This figure illustrates the capacity of central carbon metabolic pathways for the metabolic groups of yeast (as designated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116942#pone.0116942.t001" target="_blank">Table 1</a>), when grown on C₆-sugars such as glucose. Biomass formation rates have been left out, since no significant differences amongst groups could be observed (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116942#pone.0116942.s013" target="_blank">S2 Table</a>). <b>(A)</b> Purely respiring yeasts, including <i>Pichia</i>, <i>Debaromyces, Eremothecium</i> and a majority of <i>Kluyveromyces</i> exhibited low glycolytic flux (GF), without any overflow metabolism (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116942#pone.0116942.s010" target="_blank">S10B Fig.</a>). <b>(B)</b> Yeast that separated from the <i>Eremothecium</i> lineage, including some <i>Kluyveromyces</i>, and all <i>Lachancea, Torulaspora, Zygotorulaspora</i> and the majority of WGD yeasts possessed a greater glycolytic flux than respiratory flux (RF) capacity, what results in overflow metabolism. The upregulation of the anaerobic glycolysis has provided this group of yeast with a greater energy producing apparatus that can consume glucose more rapidly under aerobic conditions (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116942#pone.0116942.s010" target="_blank">S10C Fig.</a>). <b>(C)</b> Our results can be interpreted as that traits such as overconsumption of glucose, and excess of energy producing capacity has enabled the development of a third metabolic group (including a majority of <i>Kazachstania</i> and <i>Saccharomyces</i>) that exhibit a trade-off between ethanol and energy production efficiency (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116942#pone.0116942.s010" target="_blank">S10D Fig.</a>).