Genomic Pathway Analyses of Fungal-like Marine Protists for Understanding their Biotechnological Potential and Ecological Function

Thraustochytrids are unicellular fungal-like marine protists. They have long been considered as a key player in ocean carbon cycling and also known to produce diverse interesting high-valued bioproducts (e.g. docosahexaenoic acid (DHA)). However, the genomic features for these interesting marine microbes remain largely unexplored. In this context, two thraustochytrid strains were isolated from the coastal waters of Pearl River Delta for Miseq and PacBio analyses. Genomic analyses indicated they were closely related to Aurantiochytrium_limacinum with the genome size less than 60 Mbp. Pathway analyses confirmed the existence of two fatty acid biosynthesis pathways, i.e., Standard (elongase-desaturase) and PUFA (PKS) synthase pathways, in their genomes. Several gene clusters encoding hydrolytic enzymes related to nutrient cycling (e.g., carbon and nitrogen) were also identified in the genomes of these two strains. This study provides the first-hand genomic information for deciphering fatty acid biosynthesis and better understanding ecological functions of these interesting marine microbes.