Influence of Temperature on Growth and Peak Oil Biosynthesis in a Carbon‐Limited Medium by Pythium irregulare

Kinetic analysis was investigated for a carbon‐limited medium (C/N ratio = 5.0) supporting the growth of the 5,8,11,14,17‐eicosapentaenoic acid (20:5; ω‐3) (EPA)‐accumulating fungal organism Pythium irregulare. The productivity and yield parameters at three temperatures, 14, 21, and 28°C, demonstrated growth‐coupled synthesis for lipid‐free biomass growth and lipid accumulation. For this system, the maximum specific growth rate and theoretical maximum biomass yield based on logistic growth kinetics were used to determine an activation energy of the growth process, Eg, of 36.5 kJ mol−1. At 14, 21, and 28°C, peak lipid yield occurred after culturing for 7, 4, and 3 days, respectively, with peak lipid yields of 8.14, 12.8, and 6.69 g lipid 100 g−1 glucose. At these peak yields, the maximum lipid‐free biomass productivity was achieved at the colder 14°C temperature as well as an increased concentration of EPA—10.9 wt%. Despite these enhancements, the maximum relative lipid production (PR(FA/B)) was achieved at 21°C—19.1%.