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ABSTRACT Hydrophobic feedstocks such as waste cooking oil have recently been considered for microbial biotransformation due to their abundance, low cost, and unique advantage for lipid‐derived fermentation products. Most fermentations with hydrophobic substrates are conducted at the tube or flask scale (less than 1 L total volume) or with the hydrophobic substrate comprising a small fraction of the media. Low substrate concentrations require additional feeding. Alternatively, high concentrations do not require significant dilution of the oil feedstock, which reduce volumetric requirements for larger scale fermentations. However, high‐oil‐density fermentations complicate efficient mixing and mass transfer challenges which are exacerbated at larger scales. To address this, computational fluid dynamics (CFD) models were explored to simulate three‐phase (hydrophobic, hydrophilic, and gaseous) bench (3 L) and pilot scale (4000 L) bioreactors, highlighting challenges and potential considerations. Bioreactor fermentations ofYarrowia lipolyticastrain L36DGA1 with substrate loadings of 5%, 10%, 20%, 30%, 40%, and 50% (v/v) waste cooking oil were also conducted, representing one of the highest concentrations in the reported literature. This work supports future research into and implementation of high‐oil‐density fermentations at the bench and pilot bioreactor scale.
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Biomanufacturing of value‐added products from oils or fats: A case study on cellular and fermentation engineering of Yarrowia lipolytica
Abstract 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 yeastYarrowia lipolyticaas 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 theMHY1gene in the wild typeY. lipolyticaATCC20362. 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.
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- Award ID(s):
- 1911480
- PAR ID:
- 10235913
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Biotechnology and Bioengineering
- Volume:
- 118
- Issue:
- 4
- ISSN:
- 0006-3592
- Format(s):
- Medium: X Size: p. 1658-1673
- Size(s):
- p. 1658-1673
- Sponsoring Org:
- National Science Foundation
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