Comparative transcriptomic and lipidomic analyses indicate that cold stress enhanced the production of the long C18–C22 polyunsaturated fatty acids in Aurantiochytrium sp.

Abstract

Aurantiochytrium sp. belonging to Thraustochytrids are known for their capacity to produce long-chain polyunsaturated fatty acids (PUFAs). However, effects of cold stress accompanied with staged-temperature control on the fatty acid metabolism in Aurantiochytrium sp. were rarely studied. In this study, cold stress (15°C, 5°C) was applied for Aurantiochytrium sp., with the physiological responses (morphology, growth, fatty acid profiling) and gene expression related FA synthesis, lipid metabolism, and regulatory processes was observed. Results showed that there is a significant change for the lipid types under 5°C (251 species) and 15°C (97 species) treatment. The 5°C treatment was benefit for the C18–C22 PUFAs with the yield of docosahexaenoic acid (DHA) increased to 1.25 times. After incubation at 15°C, the accumulation of eicosadienoic acid (EA) (20:2) was increased to 2.00-fold. Based on transcriptomic and qPCR analysis, an increase in genes involved in fatty acid synthase (FAS) and polyketide synthase (PKS) pathways was observed under low-temperature treatment. With upregulation of 3-ketoacyl-CoA synthase (2.44-fold), ketoreductase (2.50-fold), and dTDP-glucose 4,6-Dehydratase (rfbB) (2.31-fold) involved in PKS pathway, the accumulation of DHA was enhanced under 5°C. While, FAS and fatty elongase 3 (ELO) involved in the FAS pathway were upregulated (1.55-fold and 2.45-fold, respectively) to accumulate PUFAs at 15°C. Additionally, glycerol-3-phosphate acyltransferase (GPAT), lysophospholipid acyltransferase (LPAT), phosphatidic acid phosphatase (PAP), phosphatidylserine synthase (PSS), and phosphatidylserine decarboxylase (PSD) involved in glycerophospholipid biosynthesis were upregulated at 5°C increasing the accumulation of phosphatidic acid (PA), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylinositol (PI). However, glycolysis and the TCA cycle were inhibited under 5°C. This study provides a contribution to the application of two-staged temperature control in the Aurantiochytrium sp. fermentation for producing cold stress-enhancing PUFAs, in order to better understand the function of the key genes for future genetic engineering.

Transcriptomics aids in uncovering the metabolic shifts and molecular machinery of Schizochytrium limacinum during biotransformation of hydrophobic substrates to docosahexaenoic acid

“…However, Aurantiochytrium sp. cultivated in cold stress (5 o C) for TAG accumulation was found to have 1.2 and 12-fold upregulation of GPAT and LPAT respectively [ 96 ]. Three isoforms of DGAT were found for SR21 i.e., schi_1281 , schi_0446 and schi_1268 .…”

A phospholipid:diacylglycerol acyltransferase is involved in the regulation of phospholipids homeostasis in oleaginous Aurantiochytrium sp.

“…There are two distinct pathways for TAG biosynthesis in nature, and almost all the genes involved in these pathways had been predicted in thraustochytrids [ 22 , 23 ]. In our recent study, we found four DGATs, which are the key and rate-limiting enzymes in Kennedy pathway, in thraustochytrid Aurantiochytrium sp.…”

“…At the cell growth phase, most of the synthesized PUFAs preferentially incorporated into PL [ 3 , 16 ], and the excess PLs may migrate into TAG catalyzed by Au PDAT. In thraustochytrids, low temperature enhanced the DHA accumulation [ 23 , 25 ], which could remodel membranes to response to cold stress by improving the fluidity and integrity of the membrane. Our previous study found the expression of Au PDAT was depressed at this condition [ 26 ], which may result in the PL accumulation.…”

Current advances for omics-guided process optimization of microbial manufacturing

“… To elucidate PBPs biosynthesis's potential association in the cell To provide a direction for subsequent fermentation optimization to improve PBPs yield Saini et al ( 2021 ) P. thermoglucosidasius To resolve a previously unclear bottleneck in anaerobic fermentation To identifying the minimal required supplemented nutrients needed to sustain anaerobic growth Mol et al ( 2021 ) Comparative transcriptomics and lipidomics Aurantiochytrium sp. To elucidate the effects of different temperatures (5 °C, 15 °C) treatments on the biosynthesis of long-chain polyunsaturated fatty acids The accumulation of DHA was increased under 5 °C, the yield of eicosadienoic acid (20:2) increased at 15 °C Song et al ( 2022 ) Genomics, comparative transcriptomics and proteomics Rhodosporidium toruloides To elucidate the molecular mechanism of nitrogen-limited starvation on the accumulation of oil which was helpful for the design of medium and process control during nitrogen-limited fermentation Zhu et al ( 2012 ) Transcriptomics, proteomics, metabolomics Rhodosporidium toruloides To elucidate the molecular mechanism of phosphate-limited starvation on the accumulation of lipids To provide new substances for nutritionally limited production Wang et al ( 2018 ) Proteomics, metabolomics Phaffia rhodozyma It found that succinate increased carotenoid production mainly due to increased acetyl-CoA utilization and cellular respiration rate As a reference for the production of carotenoids from non-fermentative carbon sources Martinez-Moya et al ( 2015 ) Transcriptomics, metabolomics C. zofingiensis To elucidate the molecular mechanism of 0.2 M NaCl maximize both TAG and astaxanthin contents It provided an accumulation of biodiesel in algae under salt stress theoretical basis Mao et al ( 2020 ) Methan...…”

“…under different temperatures (5 °C, 15 °C). The study found that the accumulation of docosahexaenoic acid (DHA) increased by 1.25-fold due to upregulated expression of genes involved in fatty acid synthase (FAS) and polyketide synthase (PKS) pathways under 5 °C, and the yield of eicosadienoic acid (20:2) increased by twofold due to upregulated FAS and fatty elongase 3 involved in the FAS pathway at 15 °C (Song et al 2022 ). Besides, Zhao et al studied the effects of low (16 °C) and high (32 °C) temperature treatments on the biosynthesis of carotenoids, lipids, and exopolysaccharides (EPSs) in oleaginous red yeast R. glutinis ZHK.…”