The United States produces more than 10 million tons of waste oils and
fats each year. This paper aims to establish a new biomanufacturing
platform that convert waste oils or fats into a series of value-added
products. Our research employs the oleaginous yeast Yarrowia lipolytica
as a case study for citrate production from waste oils. First, we
conducted the CFD simulation of the bioreactor system and identified
that the extracellular mixing and mass transfer is the first limiting
factor of an oil fermentation process due to the insolubility of oil in
water. Based on the CFD simulation results, bioreactor design and
operating conditions were optimized and successfully enhanced oil uptake
and bioconversion in fed-batch fermentation experiments. After that, we
investigated the impacts of cell morphology on oil uptake, intracellular
lipid accumulation, and citrate formation by overexpressing and deleting
the MHY1 gene in the wild type Y. lipolytica. Fairly good correlations
were achieved between cell morphology and productivities of biomass,
lipid, and citrate. Finally, fermentation kinetics with both glucose and
oil substrates were compared and the oil fermentation process was
carefully evaluated. Our research results suggest that waste oils or
fats can be economical feedstocks for biomanufacturing of many
high-value products.