scholarly journals Engineering cytoplasmic acetyl-CoA synthesis decouples lipid production from nitrogen starvation in the oleaginous yeast Rhodosporidium azoricum

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Silvia Donzella ◽  
Daniela Cucchetti ◽  
Claudia Capusoni ◽  
Aurora Rizzi ◽  
Silvia Galafassi ◽  
...  
Keyword(s):  
Lipid Content ◽  
Nitrogen Starvation ◽  
Neutral Lipids ◽  
Lipid Production ◽  
Industrial Process ◽  
Wild Type ◽  
Lipid Concentration ◽  
Atp Citrate Lyase ◽  
Acetyl Coa ◽  
Engineered Strain

Abstract Background Oleaginous yeasts are able to accumulate very high levels of neutral lipids especially under condition of excess of carbon and nitrogen limitation (medium with high C/N ratio). This makes necessary the use of two-steps processes in order to achieve high level of biomass and lipid. To simplify the process, the decoupling of lipid synthesis from nitrogen starvation, by establishing a cytosolic acetyl-CoA formation pathway alternative to the one catalysed by ATP-citrate lyase, can be useful. Results In this work, we introduced a new cytoplasmic route for acetyl-CoA (AcCoA) formation in Rhodosporidium azoricum by overexpressing genes encoding for homologous phosphoketolase (Xfpk) and heterologous phosphotransacetylase (Pta). The engineered strain PTAPK4 exhibits higher lipid content and produces higher lipid concentration than the wild type strain when it was cultivated in media containing different C/N ratios. In a bioreactor process performed on glucose/xylose mixture, to simulate an industrial process for lipid production from lignocellulosic materials, we obtained an increase of 89% in final lipid concentration by the engineered strain in comparison to the wild type. This indicates that the transformed strain can produce higher cellular biomass with a high lipid content than the wild type. The transformed strain furthermore evidenced the advantage over the wild type in performing this process, being the lipid yields 0.13 and 0.05, respectively. Conclusion Our results show that the overexpression of homologous Xfpk and heterologous Pta activities in R. azoricum creates a new cytosolic AcCoA supply that decouples lipid production from nitrogen starvation. This metabolic modification allows improving lipid production in cultural conditions that can be suitable for the development of industrial bioprocesses using lignocellulosic hydrolysates.

scholarly journals Valorization of Brewers’ Spent Grain for the Production of Lipids by Oleaginous Yeast

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3052 ◽  
Author(s):  
Alok Patel ◽  
Fabio Mikes ◽  
Saskja Bühler ◽  
Leonidas Matsakas
Keyword(s):  
Lipid Content ◽  
Oleaginous Yeast ◽  
Lipid Production ◽  
Enzymatic Saccharification ◽  
Dry Weight ◽  
Lipid Concentration ◽  
Microwave Assisted ◽  
Spent Grain ◽  
Synthetic Media ◽  
By Products

Brewers’ spent grain (BSG) accounts for 85% of the total amount of by-products generated by the brewing industries. BSG is a lignocellulosic biomass that is rich in proteins, lipids, minerals, and vitamins. In the present study, BSG was subjected to pretreatment by two different methods (microwave assisted alkaline pretreatment and organosolv) and was evaluated for the liberation of glucose and xylose during enzymatic saccharification trials. The highest amount of glucose (46.45 ± 1.43 g/L) and xylose (25.15 ± 1.36 g/L) were observed after enzymatic saccharification of the organosolv pretreated BSG. The glucose and xylose yield for the microwave assisted alkaline pretreated BSG were 34.86 ± 1.27 g/L and 16.54 ± 2.1 g/L, respectively. The hydrolysates from the organosolv pretreated BSG were used as substrate for the cultivation of the oleaginous yeast Rhodosporidium toruloides, aiming to produce microbial lipids. The yeast synthesized as high as 18.44 ± 0.96 g/L of cell dry weight and 10.41 ± 0.34 g/L lipids (lipid content of 56.45 ± 0.76%) when cultivated on BSG hydrolysate with a C/N ratio of 500. The cell dry weight, total lipid concentration and lipid content were higher compared to the results obtained when grown on synthetic media containing glucose, xylose or mixture of glucose and xylose. To the best of our knowledge, this is the first report using hydrolysates of organosolv pretreated BSG for the growth and lipid production of oleaginous yeast in literature. The lipid profile of this oleaginous yeast showed similar fatty acid contents to vegetable oils, which can result in good biodiesel properties of the produced biodiesel.

Acetyl-CoA is produced by the citrate synthase homology module of ATP-citrate lyase

2021 ◽  
Author(s):  
Kenneth Verstraete ◽  
Koen H. G. Verschueren ◽  
Ann Dansercoer ◽  
Savvas N. Savvides
Keyword(s):  
Citrate Synthase ◽  
Atp Citrate Lyase ◽  
Acetyl Coa ◽  
Citrate Lyase ◽  
Homology Module

A new strategy to improve ramie degumming based on removal of the xylan branched structure

2021 ◽  
pp. 004051752110449
Author(s):  
Huihui Wang ◽  
Tong Shu ◽  
Pandeng Li ◽  
Yun Bai ◽  
Mengxiong Xiang ◽  
...  
Keyword(s):  
Removal Rate ◽  
Natural Fibers ◽  
Green Manufacturing ◽  
Operating Conditions ◽  
Ramie Fiber ◽  
Wild Type ◽  
Acetyl Xylan Esterase ◽  
Degumming Process ◽  
Main Component ◽  
Engineered Strain

Ramie fiber is known as the “king of natural fibers,” and the key to its wide application is efficient and green manufacturing. Microbial degumming has gradually become a hot area of research due to its environmental protection and mild operating conditions. However, some gummy materials remain after microbial degumming. Xylan is the main component of residual gums; its acetylated branched chains create the space barrier that makes the removal of hemicellulose difficult during ramie degumming. An acetyl xylan esterase (AXE) was obtained from Bacillus pumilus and characterized to solve this problem. Its optimum temperature and pH were 35°C and 8.0, respectively, and it had good temperature and pH stability. These properties were consistent with the conditions of ramie degumming and they laid a foundation for the application of AXE in ramie degumming. Besides, an engineered strain with a high activity of AXE was constructed successfully on the basis of the wild-type degumming strain Pectobacterium carotovorum HG-49 and used for ramie degumming. The removal rate of hemicellulose and total gums by the engineered strain increased by 4.89% and 2.53%, respectively, compared with that of the wild-type strain. Moreover, the role of this AXE in ramie degumming was further proven by X-ray diffraction and scanning electron microscopy. This study showed that AXE played an important role in the removal of hemicellulose in the degumming process of ramie fibers, thus providing a promising degumming strategy for ramie and other bast fiber plants.

Abstract 15978: Acetyl-coa Catalysis by Atp-citrate Lyase is Essential for Myofibroblast Differentiation and Persistence

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Michael P Lazaropoulos ◽  
Andrew A Gibb ◽  
Anh Huynh ◽  
Kathryn Wellen ◽  
John W Elrod
Keyword(s):  
Histone Acetylation ◽  
Transcriptional Activation ◽  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Metabolic Reprogramming ◽  
Myofibroblast Differentiation ◽  
Atp Citrate Lyase ◽  
Acetyl Coa ◽  
Matrix Deposition ◽  
Citrate Lyase

A feature of heart failure (HF) is excessive extracellular matrix deposition and cardiac remodeling by a differentiated fibroblast population known as myofibroblasts. Identifying mechanisms of myofibroblast differentiation in cardiac fibrosis could yield novel therapeutic targets to delay or reverse HF. Recent evidence suggests that myofibroblast differentiation requires metabolic reprogramming for transcriptional activation of the myofibroblast gene program by chromatin-dependent mechanisms. We previously reported that inhibition of histone demethylation blocks myofibroblast formation, however, whether histone acetylation (e.g., H3K27ac, a prominent mark associated with gene transcription) is involved in fibroblast reprogramming remains unclear. ATP-citrate lyase (ACLY) synthesizes acetyl-CoA and therein supplies acetyl-CoA to the nucleus, where it is used as a substrate by histone acetyltransferases (HATs). To define the role of acetyl-CoA metabolism in myofibroblast differentiation, we stimulated differentiation in mouse embryonic fibroblasts (MEFs) and adult mouse cardiac fibroblasts (ACFs) with the pro-fibrotic agonist transforming growth factor β (TGFβ) and treated cells with a pharmacological inhibitor of ACLY. ACLY inhibition decreased myofibroblast gene expression in ACF and MEFs in TGFβ-stimulated myofibroblast differentiation, in addition to decreasing the population of αSMA positive MEFs. Genetic deletion of ACLY in MEFs recapitulated the results observed with pharmacological inhibition. Encouragingly, the ACLY inhibitor was sufficient to revert fully differentiated myofibroblasts under continuous TGFβ stimulation to a quiescent, non-fibrotic phenotype. Altogether, our data indicate that ACLY activity is necessary for myofibroblast differentiation and persistence. We hypothesize that ACLY-dependent acetyl-CoA synthesis is necessary for histone acetylation and transcriptional activation of the myofibroblast gene program. Currently, we are examining mechanisms of ACLY-dependent chromatin remodeling in fibroblasts and the in vivo relevance of this mechanism in mutant mice. In summary, ACLY is a potential target to reverse cardiac fibrosis and lessen HF.

scholarly journals Skeletal muscle attenuation determined by computed tomography is associated with skeletal muscle lipid content

2000 ◽  
Vol 89 (1) ◽  
pp. 104-110 ◽  
Author(s):  
Bret H. Goodpaster ◽  
David E. Kelley ◽  
F. Leland Thaete ◽  
Jing He ◽  
Robert Ross
Keyword(s):  
Skeletal Muscle ◽  
Lipid Content ◽  
Ct Scans ◽  
Lipid Concentration ◽  
Muscle Lipid ◽  
Muscle Attenuation ◽  
Good Concordance ◽  
Type 2 Diabetic

The purpose of this investigation was to validate that in vivo measurement of skeletal muscle attenuation (MA) with computed tomography (CT) is associated with muscle lipid content. Single-slice CT scans performed on phantoms of varying lipid concentrations revealed good concordance between attenuation and lipid concentration ( r 2 = 0.995); increasing the phantom's lipid concentration by 1 g/100 ml decreased its attenuation by ∼1 Hounsfield unit (HU). The test-retest coefficient of variation for two CT scans performed in six volunteers was 0.51% for the midthigh and 0.85% for the midcalf, indicating that the methodological variability is low. Lean subjects had significantly higher ( P < 0.01) MA values (49.2 ± 2.8 HU) than did obese nondiabetic (39.3 ± 7.5 HU) and obese Type 2 diabetic (33.9 ± 4.1 HU) subjects, whereas obese Type 2 diabetic subjects had lower MA values that were not different from obese nondiabetic subjects. There was also good concordance between MA in midthigh and midcalf ( r = 0.60, P < 0.01), psoas ( r = 0.65, P < 0.01), and erector spinae ( r = 0.77, P < 0.01) in subsets of volunteers. In 45 men and women who ranged from lean to obese (body mass index = 18.5 to 35.9 kg/m2), including 10 patients with Type 2 diabetes mellitus, reduced MA was associated with increased muscle fiber lipid content determined with histological oil red O staining ( P = −0.43, P < 0.01). In a subset of these volunteers ( n = 19), triglyceride content in percutaneous biopsy specimens from vastus lateralis was also associated with MA ( r = −0.58, P = 0.019). We conclude that the attenuation of skeletal muscle in vivo determined by CT is related to its lipid content and that this noninvasive method may provide additional information regarding the association between muscle composition and muscle function.

scholarly journals miR-15b negatively correlates with lipid metabolism in mammary epithelial cells

2018 ◽  
Vol 314 (1) ◽  
pp. C43-C52 ◽  
Author(s):  
Meiqiang Chu ◽  
Yong Zhao ◽  
Shuai Yu ◽  
Yanan Hao ◽  
Pengfei Zhang ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Epithelial Cells ◽  
Steroid Hormones ◽  
Lipid Content ◽  
Mammary Epithelial Cells ◽  
Lipid Production ◽  
Fatty Acid Synthetase ◽  
Lipid Synthesis ◽  
Mammary Epithelial ◽  
Lipid Formation

Mammary epithelial cells are regulated by steroid hormones, growth factors, and even microRNAs. miR-15b has been found to regulate lipid metabolism in adipocytes; however, its effects on lipid metabolism in mammary epithelial cells, the cells of lipid synthesis and secretion, are as yet unknown. The main purpose of this investigation was to explore the effect of miR-15b on lipid metabolism in mammary epithelial cells, along with the underlying mechanisms. miR-15b was overexpressed or inhibited by miRNA mimics or inhibitors; subsequently, lipid formation in mammary epithelial cells, and proteins related to lipid metabolism, were investigated. Through overexpression or inhibition of miR-15b expression, the current investigation found that miR-15b downregulates lipid metabolism in mammary epithelial cells and is expressed differentially at various stages of mouse and goat mammary gland development. Inhibition of miR-15b expression increased lipid content in mammary epithelial cells through elevation of the lipid synthesis enzyme fatty acid synthetase (FASN), and overexpression of miR-15b reduced lipid content in mammary epithelial cells with decreasing levels of FASN. Moreover, the steroid hormones estradiol and progesterone decreased miR-15b expression with a subsequent increase in lipid formation in mammary epithelial cells. The expression of miR-15b was lower during lactation and negatively correlated with lipid synthesis proteins, which suggests that it may be involved in lipid synthesis and milk production. miR-15b might be a useful target for altering lipid production and milk yield.

scholarly journals The Use of Urea and Kelp Waste Extract is A Promising Strategy for Maximizing the Biomass Productivity and Lipid Content in Chlorella sorokiniana

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 463 ◽  
Author(s):  
Ali Nawaz Kumbhar ◽  
Meilin He ◽  
Abdul Razzaque Rajper ◽  
Khalil Ahmed Memon ◽  
Muhammad Rizwan ◽  
...  
Keyword(s):  
Lipid Content ◽  
Fossil Fuels ◽  
Fossil Fuel ◽  
Lipid Production ◽  
Total Lipid Content ◽  
Biomass Productivity ◽  
Chlorella Sorokiniana ◽  
Biofuel Production ◽  
Promising Strategy ◽  
Waste Extract

The decline in fossil fuel reserves has forced researchers to seek out alternatives to fossil fuels. Microalgae are considered to be a promising feedstock for sustainable biofuel production. Previous studies have shown that urea is an important nitrogen source for cell growth and the lipid production of microalgae. The present study investigated the effect of different concentrations of urea combined with kelp waste extract on the biomass and lipid content of Chlorella sorokiniana. The results revealed that the highest cell density, 20.36 × 107 cells−1, and maximal dry biomass, 1.70 g/L, were achieved in the presence of 0.5 g/L of urea combined with 8% kelp waste extract. Similarly, the maximum chlorophyll a, b and beta carotenoid were 10.36 mg/L, 7.05, and 3.01 mg/L, respectively. The highest quantity of carbohydrate content, 290.51 µg/mL, was achieved in the presence of 0.2 g/L of urea and 8% kelp waste extract. The highest fluorescence intensity, 40.05 × 107 cells−1, and maximum total lipid content (30%) were achieved in the presence of 0.1 g/L of urea and 8% kelp waste extract. The current study suggests that the combination of urea and kelp waste extract is the best strategy to enhance the biomass and lipid content in Chlorella sorokiniana.

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