Production of prostaglandins in transgenic Arabidopsis thaliana

Prostaglandin production by the microalga with heterologous expression of cyclooxygenase

Prostaglandins (PGs) are the physiologically active compounds synthesized from C20 polyunsaturated fatty acids (PUFAs) by cyclooxygenase (COX) and a series of PG synthases, and are utilized as pharmaceuticals. Currently, commercialized PGs are mainly produced by chemical synthesis under harsh conditions. By contrast, bioproduction of PGs can be an alternative, environmental-friendly, and inexpensive process with genetic engineering of model plants, although these conventional host organisms contain a limited quantity of PG precursors. In this study, we established an efficient PG production process using the genetically engineered microalga Fistulifera solaris which is rich in C20 PUFAs. A cox gene derived from the red alga Agarophyton vermiculophyllum was introduced into F. solaris. As a result, a transformant clone with high cox expression produced PGs (i.e., PGD₂ , PGE₂ , PGF_2α , and 15-ketoPGF_2α derived from arachidonic acid, and PGD₃ , PGE₃ , and PGF_3α derived from eicosapentaenoic acid) as revealed by liquid chromatography/mass spectrometry. The total content of PGs was 1290.4 ng/g of dry cell weight, which was higher than that produced in the transgenic plant reported previously. The results obtained in this study indicate that the C20 PUFA-rich microalga functionally expressing COX is a promising host for PG bioproduction.

Systematic genome analysis of a novel arachidonic acid-producing strain uncovered unique metabolic traits in the production of acetyl-CoA-derived products in Mortierellale fungi

The fungi in order Mortierellales are attractive producers for long-chain polyunsaturated fatty acids (PUFAs). Here, the genome sequencing and assembly of a novel strain of Mortierella sp. BCC40632 were done, yielding 65 contigs spanning of 49,964,116 total bases with predicted 12,149 protein-coding genes. We focused on the acetyl-CoA in relevant to its derived metabolic pathways for biosynthesis of macromolecules with biological functions, including PUFAs, eicosanoids and carotenoids. By comparative genome analysis between Mortierellales and Mucorales, the signature genetic characteristics of the arachidonic acid-producing strains, including Δ⁵-desaturase and GLELO-like elongase, were also identified in the strain BCC40632. Remarkably, this fungal strain contained only n-6 pathway of PUFA biosynthesis due to the absence of Δ¹⁵-desaturase or ω3-desaturase gene in contrast to other Mortierella species. Four putative enzyme sequences in the eicosanoid biosynthetic pathways were identified in the strain BCC40632 and others Mortierellale fungi, but were not detected in the Mucorales. Another unique metabolic trait of the Mortierellales was the inability in carotenoid synthesis as a result of the lack of phytoene synthase and phytoene desaturase genes. The findings provide a perspective in strain optimization for production of tailored-made products with industrial applications.