Biomanufacturing of value‐added products from oils or fats: A case study on cellular and fermentation engineering of Yarrowia lipolytica

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 converts waste oils or fats into a series of value‐added products. Our research employs the oleaginous yeast Yarrowia lipolytica as a case study for citric acid (CA) production from waste oils. First, we conducted the computational fluid dynamics (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, the 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 CA formation by overexpressing and deleting the MHY1 gene in the wild type Y. lipolytica ATCC20362. Fairly good linear correlations (R2 > 0.82) were achieved between cell morphology and productivities of biomass, lipid, and CA. Finally, fermentation kinetics with both glucose and oil substrates were compared and the oil fermentation process was carefully evaluated. Our study suggests that waste oils or fats can be economical feedstocks for biomanufacturing of many high‐value products. Plant oils/animal fats can be economical feedstocks suitable for biomanufacturing a series of high‐value products by the oleaginous yeast Yarrowia lipolytica. Fermentation engineering was conducted by CFD‐guided bioreactor design and optimization of operating conditions to improve extracellular mixing and mass transfer of oils/fats in aqueous medium. The effect of cell morphology on both intracellular fatty acid assimilation and extracellular uptake of oils/fats was also studied. The research results will help establish a new biomanufacturing platform that uses any hydrophobic substrates.