Reaction of Sulfur and Sustainable Algae Oil for Polymer Synthesis and Enrichment of Saturated Triglycerides

There is growing interest in the bio-based production of lipids from algae. These lipids have a range of uses including nutritional supplements and precursors to biodiesel. Single-cell thraustochytrids are especially attractive in this regard in that they can produce over 50% of their weight as triglycerides. Furthermore, the distribution of saturated and unsaturated triglycerides can be modulated by changes in strain variation and modulation of fermentation conditions. Nonetheless, there remains a need for versatile downstream processing to enrich these so-called “single cell oils” into classes based on degree of unsaturation. In this study, we report a novel strategy for enriching saturated triglycerides produced in thraustochytrids. The method features direct reaction of elemental sulfur with the algae oil extract. The sulfur copolymerizes with >90% of the unsaturated triglycerides, providing a new route to a class of materials previously used in environmental remediation, Li-S battery cathodes, slow-release fertilisers, and insulation. The unreacted oil is enriched in saturated triglycerides, which can be isolated by extraction for potential use in biodiesel production. In this way, a single batch of sustainably produced algae oil can be converted into multiple useful products in a single step.