Using fermentation, University of Alberta researchers have developed a method to produce higher amounts of punicic acid, a healthy fatty acid found mainly in pomegranates. The findings are published in the Journal of Agricultural and Food Chemistry.
The team worked with baker's yeast that initially contained none and created a new strain with high levels of punicic acid. This offers a sustainable way to produce both the fatty acid and yeast biomass, which serves as a supplemental protein source in food and animal feed industries.
Study co-author Guanqun (Gavin) Chen, an associate professor in the Faculty of Agricultural, Life & Environmental Sciences, stated, "This means we could produce this high-value lipid much more quickly and economically in the future, without needing to use arable land, and it also shows how we can develop and nutritionally enhance sustainable sources of specialty oil."
Punicic acid, derived from the seed oil of pomegranates, has several health benefits, including cholesterol-lowering, anti-inflammatory, and anti-carcinogenic properties. However, pomegranates have a low seed-to-fruit ratio and oil yield compared to other oilseed crops like canola, making them a more costly commodity.
Utilizing a gene-editing technique known as CRISPR-based gene shuffling, Chen and co-author Juli Wang integrated specific genes involved in punicic acid synthesis directly into the genome of baker's yeast. This marks the first use of CRISPR-based gene shuffling in engineering yeast to produce unusual fatty acids from plants.
Their approach allowed for the random addition of genes to create a library, which was then screened to identify the most effective combinations. Wang explained, "We get the screening out of the best strain first and then figure out what genes are transformed. This guarantees better performance in our results, because it tells us which genes work better with one another."
The experiments resulted in an 80-fold increase in punicic acid content, reaching 26.7%, the highest level reported in engineered microorganisms or plants to date, indicating potential for commercial-scale production.
The yeast strain produced maintains a stable punicic acid content, which is promising for large-scale applications. Wang noted, "For bioindustrial production, it means that the genes that get added into the yeast don't get lost from one batch of fermentation to the next."
The discoveries have led to a provisional patent application and build upon earlier research identifying dynamics of punicic acid content in yeast. The researchers plan to grow their high-yield strain in lab-scale fermentors as a step toward commercial production.
Furthermore, their CRISPR-based gene shuffling approach could be adapted to engineer baker's yeast for other valuable unusual fatty acids, such as those from castor oil, presenting exciting potential for developing additional bioproducts.