Investigation and production of omega 3 oil rich in docosahexaenoic acid by native strain of Aurantiochytrium TA4

Omega 3 fatty acids play an important role in human health. Docosahexaenoic acid is the most important of polyunsaturated fatty acids that is supplied through the consumption of fish oil. Consequently، there is a need for new alternative sources like as single cell oils، because of possibility of heavy metal contamination in fish oil. In this research، the samples were collected from mangrove forests in the Persian Gulf and Oman Sea. The strains of marine protist were isolated in GYP medium. Oil-producing strains were screened by fluorescence microscopy. Selected strain was identified by sequencing 18s rRNA gene and polyunsaturated fatty acids profile was determined by gas chromatography. More than 20 marine protist strains were isolated. Triacylglycerol granules were detected in strain TA4 by orange fluorescent. Dyad، tetrad، octad cells and zoospore were observed in cell cycle. 18s rRNA gene sequence of this strain (1730 bp) was similar more than 97 % to Aurantiochytrium strain (Accession number: KJ938302). Its oil content is 46 % of CDW. The quantity of DHA، DPA and EPA fatty acids was 105، 46 and 26 mg per liter، respectively. Their contents were 16، 7 and 4 % of the total fatty acids، respectively. Discussion and Thraustochytrids strains have a unique ability to produce polyunsaturated fatty acids، especially DHA and can be an alternative to these valuable compounds. These strains can be used for production of omega 3 oils due to their potential for production of DHA.