Engineering triacylglycerol production from sugars in oleaginous yeasts

Kamineni, Annapurna; Shaw, J. F.

doi:10.1016/j.copbio.2019.12.022

Cited by 28 publications

(17 citation statements)

References 76 publications

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“…Metabolic engineering of the native pathway has improved lipid production in Y. lipolytica to nearly the theoretical maximal yield of 0.27 g lipid/g glucose [ 9 , 18 – 22 ], when taking into account synthesis of non-lipid yeast biomass. Engineering strategies include overexpressing genes directly implicated in TAG synthesis [ 8 , 19 , 23 , 24 ], rerouting glucose flux toward lipid precursor production [ 18 ] and deleting genes involved in lipid degradation [ 18 , 25 ] and by-product formation [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

“…Another strategy to improve glucose-to-lipid production involves rewiring central carbon metabolism to improve yield of the biosynthetic lipid precursor acetyl-CoA, the redox cofactor NADPH, or both [ 22 , 27 – 30 ]. This increases the theoretical maximum yield of the pathway and usually involves introducing heterologous enzymatic activities and creating new pathways in the organism [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

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Increasing lipid yield in Yarrowia lipolytica through phosphoketolase and phosphotransacetylase expression in a phosphofructokinase deletion strain

Kamineni

Consiglio

MacEwen

et al. 2021

Biotechnol Biofuels

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Background Lipids are important precursors in the biofuel and oleochemical industries. Yarrowia lipolytica is among the most extensively studied oleaginous microorganisms and has been a focus of metabolic engineering to improve lipid production. Yield improvement, through rewiring of the central carbon metabolism of Y. lipolytica from glucose to the lipid precursor acetyl-CoA, is a key strategy for achieving commercial success in this organism. Results Building on YB-392, a Y. lipolytica isolate known for stable non-hyphal growth and low citrate production with demonstrated potential for high lipid accumulation, we assembled a heterologous pathway that redirects carbon flux from glucose through the pentose phosphate pathway (PPP) to acetyl-CoA. We used phosphofructokinase (Pfk) deletion to block glycolysis and expressed two non-native enzymes, phosphoketolase (Xpk) and phosphotransacetylase (Pta), to convert PPP-produced xylulose-5-P to acetyl-CoA. Introduction of the pathway in a pfk deletion strain that is unable to grow and accumulate lipid from glucose in defined media ensured maximal redirection of carbon flux through Xpk/Pta. Expression of Xpk and Pta restored growth and lipid production from glucose. In 1-L bioreactors, the engineered strains recorded improved lipid yield and cell-specific productivity by up to 19 and 78%, respectively. Conclusions Yields and cell-specific productivities are important bioprocess parameters for large-scale lipid fermentations. Improving these parameters by engineering the Xpk/Pta pathway is an important step towards developing Y. lipolytica as an industrially preferred microbial biocatalyst for lipid production.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Increasing lipid yield in Yarrowia lipolytica through phosphoketolase and phosphotransacetylase expression in a phosphofructokinase deletion strain

Kamineni

Consiglio

MacEwen

et al. 2021

Biotechnol Biofuels

Self Cite

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“…After the synthesis of citrate by TCA cycle in the mitochondria, it is exported to the cytosol and converted to acetyl-CoA by ACL [ 29 , 30 ]. Acetyl-CoA carboxylase (ACC1) catalyzes the conversion of malonyl-CoA from acetyl-CoA [ 31 ]; then, the fatty acid synthase (FAS1, FAS2) complex synthesizes long-chain acyl-CoA from acetyl-CoA and malonyl-CoA using NADPH for reduction [ 32 , 33 ] (citrate-mediated acyl-CoA synthesis pathway; Figure 3 ). In our previous studies, the citrate-mediated acyl-CoA synthesis pathway-related genes greatly increased lipid productivity; mutants were expressed higher than in the parental strains on day 1 and 3.…”

Section: Resultsmentioning

confidence: 99%

Citrate-Mediated Acyl-CoA Synthesis Is Required for the Promotion of Growth and Triacylglycerol Production in Oleaginous Yeast Lipomyces starkeyi

et al. 2021

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The oleaginous yeast Lipomyces starkeyi is an excellent producer of triacylglycerol (TAG) as a feedstock for biodiesel production. To understand the regulation of TAG synthesis, we attempted to isolate mutants with decreased lipid productivity and analyze the expression of TAG synthesis-related genes in this study. A mutant with greatly decreased lipid productivity, sr22, was obtained by an effective screening method using Percoll density gradient centrifugation. The expression of citrate-mediated acyl-CoA synthesis-related genes (ACL1, ACL2, ACC1, FAS1, and FAS2) was decreased in the sr22 mutant compared with that of the wild-type strain. Together with a notion that L. starkeyi mutants with increased lipid productivities had increased gene expression, there was a correlation between the expression of these genes and TAG synthesis. To clarify the importance of citrate-mediated acyl-CoA synthesis pathway on TAG synthesis, we also constructed a strain with no ATP-citrate lyase responsible for the first reaction of citrate-mediated acyl-CoA synthesis and investigated the importance of ATP-citrate lyase on TAG synthesis. The ATP-citrate lyase was required for the promotion of cell growth and TAG synthesis in a glucose medium. This study may provide opportunities for the development of an efficient TAG synthesis for biodiesel production.

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“…The reduction of E a in the case of the CWBB is significant since components such as the essential oil deriving from the immobilization carrier (orange pulp) could have an inhibitory effect on cell activity and viability [33]. Various other factors, such as a high sugar content, can influence the E a of alcoholic fermentation and the quality of the final product [34]. In this study, the presence of antimicrobial compounds, such as limonene deriving from the immobilization carrier, did not have a significant effect on the fermentation kinetics.…”

Section: Activation Energy and Fermentation Kineticsmentioning

confidence: 99%

Refining Citrus Wastes: From Discarded Oranges to Efficient Brewing Biocatalyst, Aromatic Beer, and Alternative Yeast Extract Production

et al. 2021

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Agro-industrial wastes can be valorized as biorefinery raw materials through innovative, environmentally friendly bioprocessing for added value products. In this study, a process for citrus waste valorization within the biorefinery concept is proposed, including the development of an effective biocatalyst, based on immobilized cells, for aromatic beer production, and an alternative yeast extract (AYE) production in the same unit. Specifically, orange pulp from discarded oranges was applied as an immobilization carrier of the alcohol-resistant and cryotolerant yeast strain S. cerevisiae AXAZ-1. The yeast culture was produced by minor nutrient supplementation using diluted molasses as substrate. An effective Citrus Waste Brewing Biocatalyst (CWBB) was produced and applied for beer fermentation. The aroma-related compounds in beer produced with free yeast cells or the CWBB were evaluated by solid-phase micro-extraction (SPME) gas chromatography–mass spectrometry (GC–MS). The analysis showed that the beers produced by the CWBB had a more complex volatile profile compared with beer fermented by the free cells. More specifically, the CWBB enhanced the formation of esters and terpenes by 5- and 27-fold, respectively. In the frame of the proposed multiprocessing biorefinery concept, the spent CWBB, after it has completed its cycle of brewing batches, was used as substrate for AYE production through autolysis. The produced AYE significantly affected the yeast growth when compared to commercial yeast extract (CYE). More specifically, it promoted the biomass productivity and biomass yield factor by 60–150% and 110–170%, respectively. Thus, AYE could be successfully used for industrial cell growth as an efficient and cheaper substitute of CYE. Within a circular economy framework, the present study highlights the potential use of citrus waste to produce aromatic beer combined with AYE production as an alternative way to valorize these wastes.

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Engineering triacylglycerol production from sugars in oleaginous yeasts

Cited by 28 publications

References 76 publications

Increasing lipid yield in Yarrowia lipolytica through phosphoketolase and phosphotransacetylase expression in a phosphofructokinase deletion strain

Increasing lipid yield in Yarrowia lipolytica through phosphoketolase and phosphotransacetylase expression in a phosphofructokinase deletion strain

Citrate-Mediated Acyl-CoA Synthesis Is Required for the Promotion of Growth and Triacylglycerol Production in Oleaginous Yeast Lipomyces starkeyi

Refining Citrus Wastes: From Discarded Oranges to Efficient Brewing Biocatalyst, Aromatic Beer, and Alternative Yeast Extract Production

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