Genome analysis of the heterotrophic microalga Thraustochytrium sp. TN22 to identify genes involved in exopolysaccharide and carotenoid biosynthesis pathways

Abstract

In this study, the genome of Thraustochytrium sp. TN22, a heterotrophic marine microalga, was sequenced, assembled and annotated using the Illumina NovaSeq 6000, PacBio RS II and MinION platform to identify genes and EPS and carotenoid biosynthesis pathways. The genome of Thraustochytrium sp. TN22 consists of 38,842,079 bp with a G + C content of 66.52% and reached 90.7% gene completeness. In total, 15,208 genes were annotated, among which 14,236 genes were identified using the NCBI-nr, KEGG, GO, COG and InterProScan databases. Pathway analysis showed that EPS biosynthesis in Thraustochytrium sp. TN22 follows an ABC-dependent pathway. The carotenoids of Thraustochytrium TN22 are predicted to be synthesized via the mevalonate pathway, and the conversion of β-carotene to xanthophyll proceeds through β-cryptoxanthin and zeaxanthin intermediates. Our results will be useful for improving high-value coproducts for industrial application of thraustochytrids.

Keywords: Carotenoid; Exopolysaccharide; Genome; Next generation sequencing; Thraustochytrium sp. TN22.