Interaction of storage carbohydrates and other cyclic fluxes with central metabolism: A quantitative approach by non-stationary 13C metabolic flux analysis

• Published in: Metabolic engineering communications Vol. 3; pp. 52 - 63
• Main Authors: Suarez-Mendez, C.A., Hanemaaijer, M., ten Pierick, Angela, Wolters, J.C., Heijnen, J.J., Wahl, S.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2016; Elsevier
• Subjects: Amino acids; exports; extracellular space; Flux estimation; glucose; Glycogen; metabolic flux analysis; metabolism; Non-stationary 13C labeling; Saccharomyces cerevisiae; Trehalose; FBA; GPM; GLN; DO; Flux estimation; PRO; S7P; UTP; GLU; X5P; PFK; FBP; GLY; E4P; SUC; UDP; F6P; IDMS; GAPDH&PGK; G6PDH; METH; 2PG; AK; DHAP; 6PG; OUR; OAA; T6P; PGI; TCA; CoA; GAP; PGM; MAL; SER; Trehalose; Ribu5P; RPE; G1P; ENO; Amino acids; RPI; PPP; Rib5P; Iso-Cit; TPP; α-KG; TPS; ASP; FUM; G6P; FMH; UDPG; PYK; Glycogen; LYS; Non-stationary 13C labeling; PYR; 3PG; ACO; PMI; ALA; PEP; LEU
• ISSN: 2214-0301; 2214-0301
• DOI: 10.1016/j.meteno.2016.01.001

13C labeling experiments in aerobic glucose limited cultures of Saccharomyces cerevisiae at four different growth rates (0.054; 0.101, 0.207, 0.307h−1) are used for calculating fluxes that include intracellular cycles (e.g., storage carbohydrate cycles, exchange fluxes with amino acids), which are rearranged depending on the growth rate. At low growth rates the impact of the storage carbohydrate recycle is relatively more significant than at high growth rates due to a higher concentration of these materials in the cell (up to 560-fold) and higher fluxes relative to the glucose uptake rate (up to 16%). Experimental observations suggest that glucose can be exported to the extracellular space, and that its source is related to storage carbohydrates, most likely via the export and subsequent extracellular breakdown of trehalose. This hypothesis is strongly supported by 13C-labeling experimental data, measured extracellular trehalose, and the corresponding flux estimations. •Cyclic fluxes between large metabolite pools and central C-metabolism are studied.•Cyclic fluxes are rearranged depending on growth rate.•Impact of storage carbohydrate recycle is more significant at low growth rates.•Impact of exchange fluxes with amino acids is more significant at high growth rates.•Trehalose export and degradation seem to play a major role in glucose recycle.