Isolation and Characterization of Thraustochytrium Trk-23 Producing Docosahexaenoic Acid from North Kalimantan, Indonesia.

Abstract

<b>Background and Objective:</b> The mangrove forest located in Tarakan Bay, North Kalimantan Province, Indonesia is geographically distant from human settlement and industrial activities. Thus, it remains unaffected by the presence of human-generated waste and industrial pollutants. This study aims to isolate and characterize the microalgae Thraustochytrids from this location, which can produce docosahexaenoic acid (DHA, C22:6, n-3). It is anticipated that these microalgae possess the potential for commercial production of DHA. <b>Materials and Methods:</b> The fallen leaf sample was collected from the mangrove forest, then isolated and purified by scratching technique until a single colony state. The pure isolate then be identified by 18S rDNA. The sequences were then analyzed for similarities using the Basic Local Alignment Search Tool (BLAST). The phylogenetic trees were carried out using the MEGA 6 program. The choice of phylogenetic trees was based on maximum likelihood. <b>Results:</b> The identification 18S rDNA gene, a strain namely Trk-23, was identified as <i>Thraustochytrium</i> sp. In the optimization of the cell growth of this strain, it was found that <i>Thraustochytrium</i> Trk-23 has maximum growth at 6.0% glucose, 1.0% yeast extract and 50% natural seawater, at a pH of 5.0 and a temperature of 30°C. The maximum lipid content is 6.0 g and the DHA proportion is 41.6% of the total fatty acid content with a DHA yield is 2.5 g L<sup>1</sup>. <b>Conclusion:</b> Some places in North Kalimantan are still free from industrial pollution and rich with <i>Thraustochytrium</i> sp., which is why it can find <i>Thraustochytrium</i> Trk-23. Due to its potency, <i>Thraustochytrium</i> Trk-23 is the promising candidate microalgae strain for producing DHA commercially.