Overexpression of Malonyl-CoA: ACP Transacylase in Schizochytrium sp. to Improve Polyunsaturated Fatty Acid Production

Abstract

Polyunsaturated fatty acids (PUFAs) have been widely applied in the food and medical industry. In this study, malonyl-CoA: ACP transacylase (MAT) was overexpressed through homologous recombination to improve PUFA production in Schizochytrium. The results showed that the lipid and PUFA concentration were increased by 10.1 and 24.5% with MAT overexpression, respectively. Metabolomics analysis revealed that the intracellular tricarboxylic acid cycle was weakened and glucose absorption was accelerated in the engineered strain. In the mevalonate pathway, intracellular carotene content was decreased, and the carbon flux was then redirected toward PUFA synthesis. Furthermore, a glucose fed-batch fermentation was finally performed with the engineered Schizochytrium. The total lipid yield was further increased to 110.5 g/L, 39.6% higher than the wild strain. Docosahexaenoic acid and eicosapentaenoic acid yield were enhanced to 47.39 g/L and 1.65 g/L with an increase of 81.5 and 172.5%, respectively. This study provided an effective metabolic engineering strategy for industrial PUFA production.

Integration of proteome and transcriptome refines key molecular processes underlying oil production in Nannochloropsis oceanica

“…improvement of light quantum yield by reducing antenna size [65], increasing NADPH supply for FA synthesis [66]. Furthermore, ACCase and MCMT, catalyzing the rst steps of FA synthesis in chloroplast did not increase or even decrease even after 48 h. Interestingly, overexpression of MCMT increases total lipid production in N. oceanica [67] and ACCase in P. tricornutum [68]. Therefore, overexpression of ACCase may enhance lipid production in N. oceanica, too.…”

Potential and Challenges of Improving Photosynthesis in Algae

“…Saturated and mono-unsaturated C 14 -C 20 fatty acids from microalgae are exploited for renewable liquid biofuel production, while the engineering biosynthesis of long chain-polyunsaturated fatty acids (LC-PUFAs), important components of the human diet, might become a viable option in the market of high-value food additives [114]. Metabolic engineering reports for redirecting carbon fluxes toward fatty acid production in microalgae, included the up-regulation of key biosynthetic enzymes: (i) acetyl-CoA carboxylase, catalysing the first step for fatty acid biosynthesis, was successfully over-expressed in the chloroplast of P. tricornutum [115]; (ii) malonyl-CoA ACP transacylase enzyme, which catalyses the formation of malonyl-ACP, was over-expressed in both N. oceanica and Schizochytrium spp., resulting in 31% and 39.6% total lipid increase with respect to the control genotype, respectively [116,117]; (iii) acyl-ACP thioesterases (TE), involved in the last step of fatty acids biosynthesis, was heterologously expressed in different strains of microalgae [118,119]. In Dunaliella tertiolecta, a combinational expression platform involving plant lauric acid-TE (C12TE) and medium-chain fatty acid-specific ketoacyl-ACP synthase was recently engineered, and resulted in a significant increase in lauric acid (C12:0) and myristic acid (C14:0) accumulation [120].…”

Metabolic Engineering Strategies for the Enhanced Microalgal Production of Long‐Chain Polyunsaturated Fatty Acids (LC‐PUFAs)

“…Overexpression of the G6PDH‐encoding gene using a constitutive actin promoter in the heterotrophic marine microalgae Aurantiochytrium sp. was reported to enhance the fraction of LC‐PUFAs relative to total fatty acids, particularly docosapentaenoic acid (DPA, 20:5Δ) and DHA, by 25% and 12.5%, respectively . Malic enzyme (ME) is another well‐known enzyme for generating NADPH when converting malate into pyruvate.…”

“…Thanks to their great health benefits, the global demand for LC‐PUFAs has increased in the last few years. Representative LC‐PUFAs include arachidonic acid (ARA, 20:4Δ), eicosapentaenoic acid (EPA, 20:5Δ), and docosahexaenoic acid (DHA, 22:6Δ). Sustainable production of LC‐PUFAs using heterologous production hosts has been receiving considerable attention due to a gradual decline in the supply of fish oil and environmental issues in recent years.…”