Marine fungoid producers of DHA, EPA and carotenoids from central and southern Chilean marine ecosystems

Declining fishing yields have pushed the search for sustainable alternative sources for polyunsaturated fatty acids (PUFAs). Thraustochytrids and marine yeasts (marine fungoid protists) are potential commercial sources of lipids and carotenoids. It was determined the capacity of a collection of 41 strains of marine fungoid isolated in the Humboldt Current System, to produce DHA (docosahexanoic acid), EPA (eicosapentanoic acid) and CT (total carotenoids) in commercial growing media (MS) and alternative growing mediums (PDB, GAM, BAM and MCM). The media MS and PDB exhibited the highest growth rate (0.02 h^-1), at 16 and 37°C, respectively. Thirteen of the studied strains showed high capacity to produce DHA (up to 23% dry weight) and CT (up to 18% dry weight), comparable to levels observed in Schizochytrium sp. KH105 and Rhodosporidium toruloides. Additionally, all studied strains produce small amounts of EPA (up to 0.3% of dry weight). Scanning electron microscopy reveals that strain C36 is morphologically consistent with yeasts, while partial sequencing of the 18s ribosomal gene shows 97% similarity to the genus Rhodotorula, which has not been reported until now as a producer of DHA and EPA. Finally, the strains C36, C22 and C4 offer promising potential for upscaling their production for commercial use for enriching human food and animal and larval fish feed with omega-3 and carotenoids, as well as being a source for food dyes for salmon and other products.