Kinetic modeling of photoautotropic growth and neutral lipid accumulation in terms of ammonium concentration in Chlamydomonas reinhardtii

Abstract

This study focuses on the cell growth and the neutral lipid production modeling of Chlamydomonas reinhardtii in terms of different ammonium concentrations. Autotrophy was maintained during growth in a double walled bioreactor, using Tris Phosphate (TP medium) with only CO(2) and NH(4)Cl as sole sources of carbon and nitrogen, respectively. Nitrogen depletion results in an increase in neutral lipid production with an indirect effect on the growth of algal cells. Modified Baranyi-Roberts and logistic equations were used to describe the cell growth whereas Luedeking-Piret equation was used for neutral lipid production kinetics. Sensitivity analysis shows that the model equations satisfactorily predict the cell growth and lipid production. Based on the mathematical model predictions, growing algal cells in higher ammonium containing medium initially and switching to low ammonium containing medium in a later stage may result in elevated amounts of lipid production, which may be used for scale up and commercialization.