Fed-Batch Fermentation of Yarrowia Lipolytica Using Defatted Silkworm Pupae Hydrolysate: A Dynamic Model-Based Approach for High Yield of Lipid Production

Lipid production by Yarrowia lipolytica W29 in fed-batch mode was investigated by using low-cost substitutable defatted silkworm pupae hydrolysate (DSWPH) as a feedstock. Based on the optimized lipid fermentation conditions, three media (i.e. yeast extract, DSWPH, yeast extract-DSWPH as N sources) were investigated in a batch fermentation process. The DSWPH medium displayed the optimal lipid accumulation ability with lipid yield raised by 16.13%, ratio of unsaturated fatty acids/saturated fatty acids (UFAs/SFAs) improved by 95.70%, and ratio of unsaturated fatty acids in total fatty acids (UFAs/TFAs) increased to 87.23%. The mathematical equations based on experimental data provided a good description of temporal variations such as dry cell weight, glucose consumption, and product formation in the fermentation process. The results showed that the Luedeking-Piret type equation successfully described glucose consumption and lipid accumulation in the batch culture process. A fed-batch fermentation process was then designed based on the model prediction. In the lag phase, rapid biomass growth and lipid accumulation were sequentially achieved with the adjustment of temperature, pH, and dissolved oxygen. Finally, the maximum biomass and lipid productivity were 24.01g/L and 2.76g/L/d, respectively. Thus, the DSWPH is a nice and substitutable N source for lipid production by Y. lipolytica W29 in the fed-batch mode.