Novel potential functions of amoeboid cells in thraustochytrids revealed by Aurantiochytrium limacinum BL10

Sulfo-phospho-vanillin method for screening Aurantiochytrium strains with high docosahexaenoic acid levels

Aurantiochytrium are protists found in marine and estuarine environments, known for producing high quantities of omega-3 fatty acids, particularly docosahexaenoic acid (DHA). The commercial viability of this species is currently hindered by the lack of reliable screening methods for the rapid identification of strains with high DHA content. This study developed a high-throughput screening platform based on the sulfo-phospho-vanillin (SPV) reaction, which produces a pink chromophore upon reacting with C-C double bonds in lipids. Analysis of 200 strains derived through the UV mutagenesis of the Aurantiochytrium limacinum strain BL10 revealed 7 strains that exhibited significantly elevated SPV reactivity, compared to the naïve strain (P < 0.01). Gas chromatography-mass spectrometry analysis revealed that in 4 of the 7 strains, DHA levels were significantly higher than those of the naïve strain. Among those 4 strains, the SPV reactivity values of two strains were precisely correlated with their DHA/DPA content. The SPV reaction protocol proposed in this paper has considerable potential for the high-throughput screening of Aurantiochytrium strains particularly those derived through UV mutagenesis.

Transcriptional, post-transcriptional, and post-translational regulation of polyunsaturated fatty acid synthase genes in Aurantiochytrium limacinum strain BL10: Responses to nitrogen starvation

Under nitrogen deficient conditions, the Aurantiochytrium limacinum strain BL10 greatly increases the production of docosahexaenoic acid (DHA) and n-6 docosapentaenoic acid. Researchers have yet to elucidate the mechanism by which BL10 promotes the activity of polyunsaturated fatty acid synthase (Pfa), which plays a key role in the synthesis of polyunsaturated fatty acid (PUFA). Analysis in the current study revealed that in nitrogen-depleted environments, BL10 boosts the transcription and synthesis of proteins by facilitating the expression of pfa genes via transcriptional regulation. It was also determined that BL10 adjusts the lengths of the 5'- and 3'-untranslated regions (suggesting post-transcriptional regulation) and modifies the ratio of two Pfa1 isoforms to favor PUFA production via post-translational regulation (ubiquitination). These findings clarify the exceptional DHA production of BL10 and provide additional insights into the regulatory mechanisms of PUFA biosynthesis in Aurantiochytrium.

Emerging prospects of microbial production of omega fatty acids: Recent updates

Healthy foods containing omega-3/omega-6 polyunsaturated fatty acids (PUFAs) have been in great demand because of their unique dietary and health properties. Reduction in chronic inflammatory and autoimmune diseases has shown their therapeutic and health-promoting effects when consumed under recommended ratio 1:1-1:4, however imbalanced ratios (>1:4, high omega-6) enhance these risks. The importance of omega-6 is apparent however microbial production favors larger production of omega-3. Current research focus is prerequisite to designing omega-6 production strategies for better application prospects, for which thraustochytrids could be promising due to higher lipid productivity. This review provides recent updates on essential fatty acids production from potential microbes and their application, especially major insights on omega research, also discussed the novel possible strategies to promote omega-3 and omega-6 accumulation via engineering and omics approaches. It covers strategies to block the conversion of omega-6 into omega-3 by enzyme inhibition, nanoparticle-mediated regulation and/or metabolic flux regulation, etc.