Quantification of metabolism in Saccharomyces cerevisiae under hyperosmotic conditions using elementary mode analysis

  • Jignesh H. Parmar
  • Sharad Bhartiya
  • K. V. Venkatesh
Systems Biotechnology

Abstract

Yeast metabolism under hyperosmotic stress conditions was quantified using elementary mode analysis to obtain insights into the metabolic status of the cell. The fluxes of elementary modes were determined as solutions to a linear program that used the stoichiometry of the elementary modes as constraints. The analysis demonstrated that distinctly different sets of elementary modes operate under normal and hyperosmotic conditions. During the adaptation phase, elementary modes that only produce glycerol are active, while elementary modes that yield biomass, ethanol, and glycerol become active after the adaptive phase. The flux distribution in the metabolic network, calculated using the fluxes in the elementary modes, was employed to obtain the flux ratio at key nodes. At the glucose 6-phosphate (G6P) node, 25% of the carbon influx was diverted towards the pentose phosphate pathway under normal growth conditions, while only 0.3% of the carbon flux was diverted towards the pentose phosphate pathway during growth at 1 M NaCl, indicating that cell growth is arrested under hyperosmotic conditions. Further, objective functions were used in the linear program to obtain optimal solution spaces corresponding to the different accumulation rates. The analysis demonstrated that while biomass formation was optimal under normal growth conditions, glycerol synthesis was closer to optimal during adaptation to osmotic shock.

Keywords

Yeast Central metabolism Hyperosmotic stress Elementary mode analysis Optimal feasible space 

Supplementary material

10295_2012_1090_MOESM1_ESM.doc (47 kb)
Supplementary material 1 (DOC 47 kb)

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Copyright information

© Society for Industrial Microbiology and Biotechnology 2012

Authors and Affiliations

  • Jignesh H. Parmar
    • 1
  • Sharad Bhartiya
    • 1
  • K. V. Venkatesh
    • 1
  1. 1.Department of Chemical EngineeringIndian Institute of Technology, BombayMumbaiIndia

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