Characterization and Application of Marine Microbial Omega-3 Polyunsaturated Fatty Acid Synthesis.

The long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs) EPA (20:5n-3) and DHA (22:6n-3) are widely recognized as beneficial to human health and development. Select lineages of cosmopolitan marine prokaryotic and eukaryotic microorganisms synthesize these compounds via a unique fatty acid synthase/polyketide synthase mechanism that is distinct from the canonical desaturase/elongase-mediated pathway employed by the majority of eukaryotic single-cell microorganisms and metazoans. This "Pfa synthase" mechanism is highly efficient and has been co-opted for the large-scale industrial production of n-3 LC-PUFAs for commercial applications. Both prokaryotic and eukaryotic microbes containing this pathway can be readily isolated from marine environments and maintained in culture under laboratory conditions. Some strains are genetically tractable and have established methods for genetic modification. The discussion and methods presented here should be useful for the exploitation and optimization of n-3 LC-PUFA products from marine microorganisms.