Sustainable production of lipids from cocoa fatty acid distillate fermentation driven by adaptive evolution in Yarrowia lipolytica.

Single cell oil production using oleaginous yeasts is a promising alternative to animal and plant-derived lipids. But substrate costs for microbial fermentation are a major bottleneck. Using side streams as alternative to substrates like glucose, for growing yeast, is a potential cost-effective solution. By combining a previously reported process of growing yeasts on a solid cocoa fatty acid distillate side stream with adaptive evolution techniques, the growth of oleaginous yeast Yarrowia lipolytica was improved by 2-fold. The lipid titre was also boosted by more than 3-fold. Using transcriptomics, key genes were identified that are possibly involved in tailoring of lipid composition, side stream utilisation and enhancement of lipid titres. Candidate genes were also identified that might enable efficient growth and utilization of fatty acids and triacylglycerides found in cocoa fatty acid distillate. In summary, this research has improved the understanding of side stream utilisation for lipid production in oleaginous yeast.

Single cell protein and oil production from solid cocoa fatty acid distillates co-fed ethanol.

The use of solid lipid sidestreams have been overlooked as a feedstock for the production of microbial biomass for food and feed applications and little to no recent work has examined the utilization of solid fatty acid distillates (FADs), which are a significant residue from vegetable oil processing. Yarrowia lipolytica and Rhodosporidium toruloides cultivated on cocoa fatty acid distillates (CFAD) generated final cell dry weight values > 40 g/L, with strong productivity (3.3 g/L·h) and rich protein (>45%) and lipid content (>25%). Interestingly, microbial oils were > 65% unsaturated fatty acids, compared < 20% unsaturated content in FAD. Importantly, to overcome mass-transfer limitations associated with bioconversion of solid lipid residues, ethanol was applied as a co-substrate to solubilize FAD residues. Here, FAD residues from cocoa deodorization have been demonstrated to be high energy feedstocks that represent an attractive substrate for the production of both single cell protein and oil (SCPO).