4. Conclusion
To the best of our knowledge, it is the first time that the functionality of the TCA cycle and glyoxylate shunt during wheat bread dough fermentation is studied. Despite various reports on the functionality of the reductive pathway of the TCA cycle during anaerobic fermentation, we found no evidence for activity in this pathway during dough fermentation. By contrast, deletion of the genes responsible for the oxidative pathway of the TCA cycle and the glyoxylate shunt strongly affected the fermentation rate of yeast and the succinic acid levels produced during dough fermentation. Although the TCA cycle genes are likely downregulated during dough fermentation due to the presence of high sugar levels and the apparent anaerobic conditions in dough, deletion of the genes responsible for important enzymes in this cycle led to significant changes in the level of succinic acid during dough fermentation, suggesting at least a basal level of activity in the TCA pathway.