KINETIC MODEL OF COMMERCIAL GLUCOSE-AFFECTED GROWTH AND MICROBIAL OIL PRODUCTION OF OLEAGINOUS YEAST Pseudozyma parantarctica CHC28

Abstract

This research proposed to study the effect of commercial glucose concentration in a nitrogen-limiting medium on the growth of Pseudozyma parantarctica CHC28 and to estimate the kinetic parameters of fermentation. The biomass, microbial oil, biomass production rate (Q_x), and oil production rate (Q_p) increased dramatically and reached 22.10±1.95 g/L, 10.99±1.31 g/L, 0.184±0.016 g/L h, and 0.092±0.011 g/L h, respectively, when glucose concentration was increased to 100 g/L (C/N ratio = 333). In contrast, these results showed a decrease when glucose and C/N ratio were higher than 100 g/L and 333, respectively. Concurrently, the oil content showed a continuous rise as the glucose and C/N ratio increased. Furthermore, the maximum specific growth rate (μ_max) declined sharply when P. parantarctica was cultivated under high glucose concentration. It was therefore suggested that the glucose concentration could affect the growth of oleaginous yeast because of osmotic pressure and C/N ratio. For the bioreactor scale, biomass, microbial oil, and oil content were enhanced to 29.92 g/L, 15.13 g/L, and 50.57 %w/w, respectively, at 120 hrs of cultivation. The mathematical models could describe the effect of glucose concentration on both yeast growth and microbial oil production. Thus, the kinetic model satisfactorily fitted the experimental data relating to oleaginous growth, microbial oil production, and substrate consumption.