Characterization and PUFA production of Aurantiochytrium limacinum BUCHAXM 122 isolated from fallen mangrove leaves

Aurantiochytrium limacinum BUCHAXM 122, a strain of thraustochytrid microorganism is potentially an alternative source of essential nutrients for commercial products. In this study, the strain was screened for its characterization and determination of polyunsaturated fatty acid (PUFA) production. Cells were isolated from fallen mangrove leaves, and grown in a glucose-yeast extract-peptone (GYP) medium. Their morphology, life cycle, biomass, fatty acid, extracellular enzymes and major elements were also investigated. Colonies occurred prominently on the fourth day of cultivation, appearing opaque white in color and containing large numbers of amoeboid cells. These thraustochytrids were observed to have a multi-stage life cycle, developing through zoospore, vegetative and zoosporangium stages with a life span of approximately 24 h. Zoospores developed into vegetative cells within 10-12 h and vegetative cells developed into zoosporangia, releasing zoospores, within approximately 10-15 h. Results showed that A. limacinum BUCHAXM 122 produced highest biomass at 108 h, with 23.85 +/- 1.02 g/l dry weight. The isolates had high content of docosahexaenoic acid (DHA; 30.31 +/- 5.88% of total fatty acids), indicating that they could serve as a fatty acid source for human consumption and aquaculture feeds. Major elemental analysis showed that cells contained 57% carbon, 29% oxygen, 9% hydrogen, 4% nitrogen and 1% sulfur. Extracellular degradative enzymes including protease, lipase, urease, alpha-glucosidase and phosphatase activities were also detected.