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Nano on micro: tuning microbial metabolisms by nano-based artificial mediators to enhance and expand production of biochemicals. Curr Opin Biotechnol 2020; 64:161-168. [PMID: 32361627 DOI: 10.1016/j.copbio.2020.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/27/2020] [Accepted: 03/29/2020] [Indexed: 12/27/2022]
Abstract
Advances in synthetic biology and metabolic engineering across the past few decades have enabled the successful production of many novel chemicals. However, bioproduction of such chemicals is often limited by low yield and titer due to disrupted metabolic homeostasis. Finely tuning cellular metabolism to restore robust metabolic functions entails various genetic modifications, which is often not practical. Alternatively, artificial mediators capable of tailoring microbial metabolisms open a new avenue for restoring physiological functions. In this context, nanoparticle-based artificial mediators have been pursued to tune cellular metabolisms. They can not only enhance production of molecules from endogenous metabolism, but also expand bioproducts spectrum. Here, we reviewed recent advances toward the employment of nano-based artificial mediators for the tuning of cellular metabolism, with a focus on their positive effects on electron transfer and pathway flux. Perspectives for potential applications of artificial mediators for mediating microbial metabolisms in the future were also provided.
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52
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Wang L, Chen L, Yang S, Tan X. Photosynthetic Conversion of Carbon Dioxide to Oleochemicals by Cyanobacteria: Recent Advances and Future Perspectives. Front Microbiol 2020; 11:634. [PMID: 32362881 PMCID: PMC7181335 DOI: 10.3389/fmicb.2020.00634] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Accepted: 03/20/2020] [Indexed: 11/21/2022] Open
Abstract
Sustainable production of biofuels and biochemicals has been broadly accepted as a solution to lower carbon dioxide emissions. Besides being used as lubricants or detergents, oleochemicals are also attractive biofuels as they are compatible with existing transport infrastructures. Cyanobacteria are autotrophic prokaryotes possessing photosynthetic abilities with mature genetic manipulation systems. Through the introduction of exogenous or the modification of intrinsic metabolic pathways, cyanobacteria have been engineered to produce various bio-chemicals and biofuels over the past decade. In this review, we specifically summarize recent progress on photosynthetic production of fatty acids, fatty alcohols, fatty alk(a/e)nes, and fatty acid esters by genetically engineered cyanobacteria. We also summarize recent reports on fatty acid and lipid metabolisms of cyanobacteria and provide perspectives for economic cyanobacterial oleochemical production in the future.
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Affiliation(s)
- Li Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, China
| | - Liyuan Chen
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, China
| | - Shihui Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, China
| | - Xiaoming Tan
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, China
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53
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Xue P, Si T, Mishra S, Zhang L, Choe K, Sweedler JV, Zhao H. A mass spectrometry-based high-throughput screening method for engineering fatty acid synthases with improved production of medium-chain fatty acids. Biotechnol Bioeng 2020; 117:2131-2138. [PMID: 32219854 DOI: 10.1002/bit.27343] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 03/07/2020] [Accepted: 03/22/2020] [Indexed: 01/09/2023]
Abstract
Microbial cell factories have been extensively engineered to produce free fatty acids (FFAs) as key components of crucial nutrients, soaps, industrial chemicals, and fuels. However, our ability to control the composition of microbially synthesized FFAs is still limited, particularly, for producing medium-chain fatty acids (MCFAs). This is mainly due to the lack of high-throughput approaches for FFA analysis to engineer enzymes with desirable product specificity. Here we report a mass spectrometry (MS)-based method for rapid profiling of MCFAs in Saccharomyces cerevisiae by using membrane lipids as a proxy. In particular, matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) MS was used to detect shorter acyl chain phosphatidylcholines from membrane lipids and a higher m/z peak ratio at 730 and 758 was used as an indication for improved MCFA production. This colony-based method can be performed at a rate of ~2 s per sample, representing a substantial improvement over gas chromatography-MS (typically >30 min per sample) as the gold standard method for FFA detection. To demonstrate the power of this method, we performed site-saturation mutagenesis of the yeast fatty acid synthase and identified nine missense mutations that resulted in improved MCFA production relative to the wild-type strain. Colony-based MALDI-ToF MS screening provides an effective approach for engineering microbial fatty acid compositions in a high-throughput manner.
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Affiliation(s)
- Pu Xue
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Tong Si
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Shekhar Mishra
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Linzixuan Zhang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Kisurb Choe
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Jonathan V Sweedler
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
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54
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Discovery of a Regulatory Subunit of the Yeast Fatty Acid Synthase. Cell 2020; 180:1130-1143.e20. [DOI: 10.1016/j.cell.2020.02.034] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/23/2019] [Accepted: 02/12/2020] [Indexed: 11/23/2022]
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55
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Czumaj A, Śledziński T. Biological Role of Unsaturated Fatty Acid Desaturases in Health and Disease. Nutrients 2020; 12:nu12020356. [PMID: 32013225 PMCID: PMC7071289 DOI: 10.3390/nu12020356] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/20/2020] [Accepted: 01/28/2020] [Indexed: 12/21/2022] Open
Abstract
Polyunsaturated fatty acids (PUFAs) are considered one of the most important components of cells that influence normal development and function of many organisms, both eukaryotes and prokaryotes. Unsaturated fatty acid desaturases play a crucial role in the synthesis of PUFAs, inserting additional unsaturated bonds into the acyl chain. The level of expression and activity of different types of desaturases determines profiles of PUFAs. It is well recognized that qualitative and quantitative changes in the PUFA profile, resulting from alterations in the expression and activity of fatty acid desaturases, are associated with many pathological conditions. Understanding of underlying mechanisms of fatty acid desaturase activity and their functional modification will facilitate the development of novel therapeutic strategies in diseases associated with qualitative and quantitative disorders of PUFA.
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56
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Kasbawati, Kalondeng A, Sulfahri. A numerical study of the sensitivity of ethanol flux to the existence of co-factors in the Central metabolism of a yeast cell using multi-substrate enzymes kinetic modelling. BIOTECHNOL BIOTEC EQ 2020. [DOI: 10.1080/13102818.2020.1758593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Affiliation(s)
- Kasbawati
- Department of Mathematics, Universitas Hasanuddin, Makassar, Indonesia
| | - Anisa Kalondeng
- Department of Statistics, Universitas Hasanuddin, Makassar, Indonesia
| | - Sulfahri
- Department of Biology, Universitas Hasanuddin, Makassar, Indonesia
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57
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Liu Y, Chen J, Khusnutdinova AN, Correia K, Diep P, Batyrova KA, Nemr K, Flick R, Stogios P, Yakunin AF, Mahadevan R. A novel C-terminal degron identified in bacterial aldehyde decarbonylases using directed evolution. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:114. [PMID: 32612677 PMCID: PMC7325246 DOI: 10.1186/s13068-020-01753-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 06/16/2020] [Indexed: 05/10/2023]
Abstract
BACKGROUND Aldehyde decarbonylases (ADs), which convert acyl aldehydes into alkanes, supply promising solution for producing alkanes from renewable feedstock. However the instability of ADs impedes their further application. Therefore, the current study aimed to investigate the degradation mechanism of ADs and engineer it towards high stability. RESULTS Here, we describe the discovery of a degradation tag (degron) in the AD from marine cyanobacterium Prochlorococcus marinus using error-prone PCR-based directed evolution system. Bioinformatic analysis revealed that this C-terminal degron is common in bacterial ADs and identified a conserved C-terminal motif, RMSAYGLAAA, representing the AD degron (ADcon). Furthermore, we demonstrated that the ATP-dependent proteases ClpAP and Lon are involved in the degradation of AD-tagged proteins in E. coli, thereby limiting alkane production. Deletion or modification of the degron motif increased alkane production in vivo. CONCLUSION This work revealed the presence of a novel degron in bacterial ADs responsible for its instability. The in vivo experiments proved eliminating or modifying the degron could stabilize AD, thereby producing higher titers of alkanes.
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Affiliation(s)
- Yilan Liu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Jinjin Chen
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Anna N. Khusnutdinova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Kevin Correia
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Patrick Diep
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Khorcheska A. Batyrova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Kayla Nemr
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Robert Flick
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Peter Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
| | - Alexander F. Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
- Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, LL57 2UW UK
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
- Institute of Biomedical Engineering, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 Canada
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58
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Bergman A, Vitay D, Hellgren J, Chen Y, Nielsen J, Siewers V. Effects of overexpression of STB5 in Saccharomyces cerevisiae on fatty acid biosynthesis, physiology and transcriptome. FEMS Yeast Res 2019; 19:5423327. [PMID: 30924859 PMCID: PMC6755256 DOI: 10.1093/femsyr/foz027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 03/27/2019] [Indexed: 12/16/2022] Open
Abstract
Microbial conversion of biomass to fatty acids (FA) and products derived thereof is an attractive alternative to the traditional oleochemical production route from animal and plant lipids. This study examined if NADPH-costly FA biosynthesis could be enhanced by overexpressing the transcription factor Stb5 in Saccharomyces cerevisiae. Stb5 activates expression of multiple genes encoding enzymes within the pentose phosphate pathway (PPP) and other NADPH-producing reactions. Overexpression of STB5 led to a decreased growth rate and an increased free fatty acid (FFA) production during growth on glucose. The improved FFA synthetic ability in the glucose phase was shown to be independent of flux through the oxidative PPP. RNAseq analysis revealed that STB5 overexpression had wide-ranging effects on the transcriptome in the batch phase, and appeared to cause a counterintuitive phenotype with reduced flux through the oxidative PPP. During glucose limitation, when an increased NADPH supply is likely less harmful, an overall induction of the proposed target genes of Stb5 (eg. GND1/2, TAL1, ALD6, YEF1) was observed. Taken together, the strategy of utilizing STB5 overexpression to increase NADPH supply for reductive biosynthesis is suggested to have potential in strains engineered to have strong ability to consume excess NADPH, alleviating a potential redox imbalance.
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Affiliation(s)
- Alexandra Bergman
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, SE41296, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, SE41296 Gothenburg, Sweden
| | - Dóra Vitay
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, SE41296, Gothenburg, Sweden
| | - John Hellgren
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, SE41296, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, SE41296 Gothenburg, Sweden
| | - Yun Chen
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, SE41296, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, SE41296 Gothenburg, Sweden
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, SE41296, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, SE41296 Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, DK2800 Kgs. Lyngby, Denmark
| | - Verena Siewers
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, SE41296, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, SE41296 Gothenburg, Sweden
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59
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Arbter P, Sinha A, Troesch J, Utesch T, Zeng AP. Redox governed electro-fermentation improves lipid production by the oleaginous yeast Rhodosporidium toruloides. BIORESOURCE TECHNOLOGY 2019; 294:122122. [PMID: 31525584 DOI: 10.1016/j.biortech.2019.122122] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/03/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
Electro-fermentation (EF) is a promising technique to increase the performance of bioprocesses. Here, the effect of EF on the lipid production by the yeast Rhodosporidium toruloides is studied. First, an in silico analysis was performed to unveil possible lipid yield increase and metabolic shifts by EF. Subsequently, cathodic EF (CEF) and anodic EF (AEF) were experimentally tested at different pO2 levels. CEF enabled artificial lowering of the extracellular redox potential to less than -200 mV even under strictly aerobic conditions. CEF and AEF both positively affected lipid yield and productivity. Additional CEF cultivations with the redox mediator Neutral Red yielded an immense increase in the ratio of saturated fatty acids (from 37% to 50%). Overall, this work demonstrates that EF offers broad potential to improve microbial lipid production. In this context, the use of redox mediators might be of special future interest for the production of cocoa-butter equivalents.
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Affiliation(s)
- Philipp Arbter
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, D-21073 Hamburg, Germany
| | - Aakanksha Sinha
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, D-21073 Hamburg, Germany
| | - Julie Troesch
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, D-21073 Hamburg, Germany
| | - Tyll Utesch
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, D-21073 Hamburg, Germany
| | - An-Ping Zeng
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, D-21073 Hamburg, Germany; Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, North Third Ring Road 15, Chaoyang District, 100029 Beijing, China.
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60
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Unrean P, Tee KL, Wong TS. Metabolic pathway analysis for in silico design of efficient autotrophic production of advanced biofuels. BIORESOUR BIOPROCESS 2019. [DOI: 10.1186/s40643-019-0282-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractHerein, autotrophic metabolism of Cupriavidus necator H16 growing on CO2, H2 and O2 gas mixture was analyzed by metabolic pathway analysis tools, specifically elementary mode analysis (EMA) and flux balance analysis (FBA). As case studies, recombinant strains of C. necator H16 for the production of short-chain (isobutanol) and long-chain (hexadecanol) alcohols were constructed and examined by a combined tools of EMA and FBA to comprehensively identify the cell’s metabolic flux profiles and its phenotypic spaces for the autotrophic production of recombinant products. The effect of genetic perturbations via gene deletion and overexpression on phenotypic space of the organism was simulated to improve strain performance for efficient bioconversion of CO2 to products at high yield and high productivity. EMA identified multiple gene deletion together with controlling gas input composition to limit phenotypic space and push metabolic fluxes towards high product yield, while FBA identified target gene overexpression to debottleneck rate-limiting fluxes, hence pulling more fluxes to enhance production rate of the products. A combination of gene deletion and overexpression resulted in designed mutant strains with a predicted yield of 0.21–0.42 g/g for isobutanol and 0.20–0.34 g/g for hexadecanol from CO2. The in silico-designed mutants were also predicted to show high productivity of up to 38.4 mmol/cell-h for isobutanol and 9.1 mmol/cell-h for hexadecanol under autotrophic cultivation. The metabolic modeling and analysis presented in this study could potentially serve as a valuable guidance for future metabolic engineering of C. necator H16 for an efficient CO2-to-biofuels conversion.
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61
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Ferreira R, Skrekas C, Hedin A, Sánchez BJ, Siewers V, Nielsen J, David F. Model-Assisted Fine-Tuning of Central Carbon Metabolism in Yeast through dCas9-Based Regulation. ACS Synth Biol 2019; 8:2457-2463. [PMID: 31577419 DOI: 10.1021/acssynbio.9b00258] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Engineering Saccharomyces cerevisiae for industrial-scale production of valuable chemicals involves extensive modulation of its metabolism. Here, we identified novel gene expression fine-tuning set-ups to enhance endogenous metabolic fluxes toward increasing levels of acetyl-CoA and malonyl-CoA. dCas9-based transcriptional regulation was combined together with a malonyl-CoA responsive intracellular biosensor to select for beneficial set-ups. The candidate genes for screening were predicted using a genome-scale metabolic model, and a gRNA library targeting a total of 168 selected genes was designed. After multiple rounds of fluorescence-activated cell sorting and library sequencing, the gRNAs that were functional and increased flux toward malonyl-CoA were assessed for their efficiency to enhance 3-hydroxypropionic acid (3-HP) production. 3-HP production was significantly improved upon fine-tuning genes involved in providing malonyl-CoA precursors, cofactor supply, as well as chromatin remodeling.
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Affiliation(s)
- Raphael Ferreira
- Department of Biology and Biological Engineering , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
- Novo Nordisk Foundation Center for Biosustainability , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
| | - Christos Skrekas
- Department of Biology and Biological Engineering , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
- Novo Nordisk Foundation Center for Biosustainability , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
| | - Alex Hedin
- Department of Biology and Biological Engineering , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
| | - Benjamín J Sánchez
- Department of Biology and Biological Engineering , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
- Novo Nordisk Foundation Center for Biosustainability , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
| | - Verena Siewers
- Department of Biology and Biological Engineering , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
- Novo Nordisk Foundation Center for Biosustainability , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
| | - Jens Nielsen
- Department of Biology and Biological Engineering , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
- Novo Nordisk Foundation Center for Biosustainability , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
- Novo Nordisk Foundation Center for Biosustainability , Technical University of Denmark , DK2800 Kgs . Lyngby , Denmark
| | - Florian David
- Department of Biology and Biological Engineering , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
- Novo Nordisk Foundation Center for Biosustainability , Chalmers University of Technology , SE412 96 Gothenburg , Sweden
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62
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Kruis AJ, Bohnenkamp AC, Patinios C, van Nuland YM, Levisson M, Mars AE, van den Berg C, Kengen SW, Weusthuis RA. Microbial production of short and medium chain esters: Enzymes, pathways, and applications. Biotechnol Adv 2019; 37:107407. [DOI: 10.1016/j.biotechadv.2019.06.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/24/2019] [Accepted: 06/09/2019] [Indexed: 12/12/2022]
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63
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Mahajan D, Sengupta S, Sen S. Strategies to improve microbial lipid production: Optimization techniques. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2019. [DOI: 10.1016/j.bcab.2019.101321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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64
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Llamas M, Magdalena JA, González-Fernández C, Tomás-Pejó E. Volatile fatty acids as novel building blocks for oil-based chemistry via oleaginous yeast fermentation. Biotechnol Bioeng 2019; 117:238-250. [PMID: 31544974 DOI: 10.1002/bit.27180] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 08/20/2019] [Accepted: 09/16/2019] [Indexed: 02/06/2023]
Abstract
Microbial oils are proposed as a suitable alternative to petroleum-based chemistry in terms of environmental preservation. These oils have traditionally been studied using sugar-based feedstock, which implies high costs, substrate limitation, and high contamination risks. In this sense, low-cost carbon sources such as volatile fatty acids (VFAs) are envisaged as promising building blocks for lipid biosynthesis to produce oil-based bioproducts. VFAs can be generated from a wide variety of organic wastes through anaerobic digestion and further converted into lipids by oleaginous yeasts (OYs) in a fermentation process. These microorganisms can accumulate in the form of lipid bodies, lipids of up to 60% wt/wt of their biomass. In this context, OY is a promising biotechnological tool for biofuel and bioproduct generation using low-cost VFA media as substrates. This review covers recent advances in microbial oil production from VFAs. Production of VFAs via anaerobic digestion processes and the involved metabolic pathways are reviewed. The main challenges as well as recent approaches for lipid overproduction are also discussed.
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Affiliation(s)
- Mercedes Llamas
- Biotechnological Processes Unit, IMDEA Energy, Móstoles, Spain
| | | | | | - Elia Tomás-Pejó
- Biotechnological Processes Unit, IMDEA Energy, Móstoles, Spain
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65
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Continuous photoproduction of hydrocarbon drop-in fuel by microbial cell factories. Sci Rep 2019; 9:13713. [PMID: 31548626 PMCID: PMC6757031 DOI: 10.1038/s41598-019-50261-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 09/09/2019] [Indexed: 11/20/2022] Open
Abstract
Use of microbes to produce liquid transportation fuels is not yet economically viable. A key point to reduce production costs is the design a cell factory that combines the continuous production of drop-in fuel molecules with the ability to recover products from the cell culture at low cost. Medium-chain hydrocarbons seem ideal targets because they can be produced from abundant fatty acids and, due to their volatility, can be easily collected in gas phase. However, pathways used to produce hydrocarbons from fatty acids require two steps, low efficient enzymes and/or complex electron donors. Recently, a new hydrocarbon-forming route involving a single enzyme called fatty acid photodecarboxylase (FAP) was discovered in microalgae. Here, we show that in illuminated E. coli cultures coexpression of FAP and a medium-chain fatty acid thioesterase results in continuous release of volatile hydrocarbons. Maximum hydrocarbon productivity was reached under low/medium light while higher irradiance resulted in decreased amounts of FAP. It was also found that the production rate of hydrocarbons was constant for at least 5 days and that 30% of total hydrocarbons could be collected in the gas phase of the culture. This work thus demonstrates that the photochemistry of the FAP can be harnessed to design a simple cell factory that continuously produces hydrocarbons easy to recover and in pure form.
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66
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Tiukova IA, Prigent S, Nielsen J, Sandgren M, Kerkhoven EJ. Genome‐scale model of
Rhodotorula toruloides
metabolism. Biotechnol Bioeng 2019; 116:3396-3408. [DOI: 10.1002/bit.27162] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 08/08/2019] [Accepted: 09/05/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Ievgeniia A. Tiukova
- Systems and Synthetic Biology, Department of Biology and Biological EngineeringChalmers University of TechnologyGothenburg Sweden
- Department of Molecular SciencesSwedish University of Agricultural SciencesUppsala Sweden
| | | | - Jens Nielsen
- Systems and Synthetic Biology, Department of Biology and Biological EngineeringChalmers University of TechnologyGothenburg Sweden
| | - Mats Sandgren
- Department of Molecular SciencesSwedish University of Agricultural SciencesUppsala Sweden
| | - Eduard J. Kerkhoven
- Systems and Synthetic Biology, Department of Biology and Biological EngineeringChalmers University of TechnologyGothenburg Sweden
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67
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Yang K, Qiao Y, Li F, Xu Y, Yan Y, Madzak C, Yan J. Subcellular engineering of lipase dependent pathways directed towards lipid related organelles for highly effectively compartmentalized biosynthesis of triacylglycerol derived products in Yarrowia lipolytica. Metab Eng 2019; 55:231-238. [DOI: 10.1016/j.ymben.2019.08.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/11/2019] [Accepted: 08/02/2019] [Indexed: 11/25/2022]
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Arhar S, Natter K. Common aspects in the engineering of yeasts for fatty acid- and isoprene-based products. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:158513. [PMID: 31465888 DOI: 10.1016/j.bbalip.2019.08.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 06/26/2019] [Accepted: 08/20/2019] [Indexed: 11/18/2022]
Abstract
The biosynthetic pathways for most lipophilic metabolites share several common principles. These substances are built almost exclusively from acetyl-CoA as the donor for the carbon scaffold and NADPH is required for the reductive steps during biosynthesis. Due to their hydrophobicity, the end products are sequestered into the same cellular compartment, the lipid droplet. In this review, we will summarize the efforts in the metabolic engineering of yeasts for the production of two major hydrophobic substance classes, fatty acid-based lipids and isoprenoids, with regard to these common aspects. We will compare and discuss the results of genetic engineering strategies to construct strains with enhanced synthesis of the precursor acetyl-CoA and with modified redox metabolism for improved NADPH supply. We will also discuss the role of the lipid droplet in the storage of the hydrophobic product and review the strategies to either optimize this organelle for higher capacity or to achieve excretion of the product into the medium.
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Affiliation(s)
- Simon Arhar
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Humboldtstrasse 50/II, 8010 Graz, Austria
| | - Klaus Natter
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Humboldtstrasse 50/II, 8010 Graz, Austria.
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69
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Marella ER, Dahlin J, Dam MI, Ter Horst J, Christensen HB, Sudarsan S, Wang G, Holkenbrink C, Borodina I. A single-host fermentation process for the production of flavor lactones from non-hydroxylated fatty acids. Metab Eng 2019; 61:427-436. [PMID: 31404648 DOI: 10.1016/j.ymben.2019.08.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/28/2019] [Accepted: 08/08/2019] [Indexed: 01/17/2023]
Abstract
Lactone flavors with fruity, milky, coconut, and other aromas are widely used in the food and fragrance industries. Lactones are produced by chemical synthesis or by biotransformation of plant-sourced hydroxy fatty acids. We established a novel method to produce flavor lactones from abundant non-hydroxylated fatty acids using yeast cell factories. Oleaginous yeast Yarrowia lipolytica was engineered to perform hydroxylation of fatty acids and chain-shortening via β-oxidation to preferentially twelve or ten carbons. The strains could produce γ-dodecalactone from oleic acid and δ-decalactone from linoleic acid. Through metabolic engineering, the titer was improved 4-fold, and the final strain produced 282 mg/L γ-dodecalactone in a fed-batch bioreactor. The study paves the way for the production of lactones by fermentation of abundant fatty feedstocks.
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Affiliation(s)
- Eko Roy Marella
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Jonathan Dahlin
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Marie Inger Dam
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Jolanda Ter Horst
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Hanne Bjerre Christensen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Suresh Sudarsan
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Guokun Wang
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Carina Holkenbrink
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark
| | - Irina Borodina
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800, Kgs, Lyngby, Denmark.
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70
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Teixeira TR, Santos GS, Turatti ICC, Paziani MH, von Zeska Kress MR, Colepicolo P, Debonsi HM. Characterization of the lipid profile of Antarctic brown seaweeds and their endophytic fungi by gas chromatography–mass spectrometry (GC–MS). Polar Biol 2019. [DOI: 10.1007/s00300-019-02529-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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71
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Sztain T, Patel A, Lee DJ, Davis TD, McCammon JA, Burkart MD. Modifying the Thioester Linkage Affects the Structure of the Acyl Carrier Protein. Angew Chem Int Ed Engl 2019; 58:10888-10892. [PMID: 31140212 DOI: 10.1002/anie.201903815] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/17/2019] [Indexed: 12/23/2022]
Abstract
At the center of many complex biosynthetic pathways, the acyl carrier protein (ACP) shuttles substrates to appropriate enzymatic partners to produce fatty acids and polyketides. Carrier proteins covalently tether their cargo via a thioester linkage to a phosphopantetheine cofactor. Due to the labile nature of this linkage, chemoenzymatic methods have been developed that involve replacement of the thioester with a more stable amide or ester bond. We explored the importance of the thioester bond to the structure of the carrier protein by using solution NMR spectroscopy and molecular dynamics simulations. Remarkably, the replacement of sulfur with other heteroatoms results in significant structural changes, thus suggesting more rigorous selections of isosteric substitutes is needed.
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Affiliation(s)
- Terra Sztain
- Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, 92093-0358, USA
| | - Ashay Patel
- Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, 92093-0358, USA
| | - D John Lee
- Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, 92093-0358, USA
| | - Tony D Davis
- Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, 92093-0358, USA
| | - J Andrew McCammon
- Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, 92093-0358, USA.,Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, 92093-0340, USA
| | - Michael D Burkart
- Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, 92093-0358, USA
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72
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Sztain T, Patel A, Lee DJ, Davis TD, McCammon JA, Burkart MD. Modifying the Thioester Linkage Affects the Structure of the Acyl Carrier Protein. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Terra Sztain
- Chemistry and Biochemistry University of California, San Diego 9500 Gilman Drive La Jolla 92093-0358 USA
| | - Ashay Patel
- Chemistry and Biochemistry University of California, San Diego 9500 Gilman Drive La Jolla 92093-0358 USA
| | - D. John Lee
- Chemistry and Biochemistry University of California, San Diego 9500 Gilman Drive La Jolla 92093-0358 USA
| | - Tony D. Davis
- Chemistry and Biochemistry University of California, San Diego 9500 Gilman Drive La Jolla 92093-0358 USA
| | - J. Andrew McCammon
- Chemistry and Biochemistry University of California, San Diego 9500 Gilman Drive La Jolla 92093-0358 USA
- Pharmacology University of California, San Diego 9500 Gilman Drive La Jolla 92093-0340 USA
| | - Michael D. Burkart
- Chemistry and Biochemistry University of California, San Diego 9500 Gilman Drive La Jolla 92093-0358 USA
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73
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Heil CS, Wehrheim SS, Paithankar KS, Grininger M. Fatty Acid Biosynthesis: Chain‐Length Regulation and Control. Chembiochem 2019; 20:2298-2321. [DOI: 10.1002/cbic.201800809] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/20/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Christina S. Heil
- Institute of Organic Chemistry and Chemical BiologyBuchmann Institute for Molecular Life ScienceGoethe University Frankfurt Max-von-Laue-Strasse 15 60438 Frankfurt am Main Germany
| | - S. Sophia Wehrheim
- Institute of Organic Chemistry and Chemical BiologyBuchmann Institute for Molecular Life ScienceGoethe University Frankfurt Max-von-Laue-Strasse 15 60438 Frankfurt am Main Germany
| | - Karthik S. Paithankar
- Institute of Organic Chemistry and Chemical BiologyBuchmann Institute for Molecular Life ScienceGoethe University Frankfurt Max-von-Laue-Strasse 15 60438 Frankfurt am Main Germany
| | - Martin Grininger
- Institute of Organic Chemistry and Chemical BiologyBuchmann Institute for Molecular Life ScienceGoethe University Frankfurt Max-von-Laue-Strasse 15 60438 Frankfurt am Main Germany
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74
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Peng H, He L, Haritos VS. Flow-cytometry-based physiological characterisation and transcriptome analyses reveal a mechanism for reduced cell viability in yeast engineered for increased lipid content. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:98. [PMID: 31044011 PMCID: PMC6477733 DOI: 10.1186/s13068-019-1435-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 04/12/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Yeast has been the focus of development of cell biofactories for the production of lipids and interest in the field has been driven by the need for sustainably sourced lipids for use in a broad range of industrial applications. Previously, we reported a metabolic engineering strategy for enhanced lipid production in yeast which delivered high per-cell lipid but with low cell growth and compromised physiology. To investigate the relationship between lipid engineering and cellular physiological responses and to identify further metabolic engineering targets, we analysed transcriptomes and measured cell physiology parameters in engineered strains. RESULTS In the engineering strategy, the central carbon pathway was reprogrammed to provide more precursors for lipid production and lipid accumulation and sequestration steps were enhanced through the expression of heterologous genes. Genes coding for enzymes within the pentose phosphate, beta-oxidation pathways, ATP and NADPH biosynthesis had lower transcript levels in engineered cells. Meanwhile, flow-cytometry analysis of fluorescent-dye stained cells showed the highest reactive oxygen species (ROS) levels and mitochondrial membrane potential (Δψm) in cells with the highest lipid content, supporting the known relationship between mitochondrial activity and ROS generation. High intracellular ROS and low membrane integrity were not ameliorated by application of antioxidants. CONCLUSIONS The limited intracellular energy supplies and the unbalanced redox environment could be regarded as targets for further lipid engineering, similarly for native lipid accumulation genes that were upregulated. Thus, lipid pathway engineering has an important effect on the central carbon pathway, directing these towards lipid production and sacrificing the precursors, energy and cofactor supply to satisfy homeostatic metabolic requirements.
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Affiliation(s)
- Huadong Peng
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800 Australia
- Present Address: Department of Bioengineering, Imperial College London, London, SW7 2AZ UK
| | - Lizhong He
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800 Australia
| | - Victoria S. Haritos
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800 Australia
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75
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Yan Q, Pfleger BF. Revisiting metabolic engineering strategies for microbial synthesis of oleochemicals. Metab Eng 2019; 58:35-46. [PMID: 31022535 DOI: 10.1016/j.ymben.2019.04.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/20/2019] [Accepted: 04/21/2019] [Indexed: 02/06/2023]
Abstract
Microbial production of oleochemicals from renewable feedstocks remains an attractive route to produce high-energy density, liquid transportation fuels and high-value chemical products. Metabolic engineering strategies have been applied to demonstrate production of a wide range of oleochemicals, including free fatty acids, fatty alcohols, esters, olefins, alkanes, ketones, and polyesters in both bacteria and yeast. The majority of these demonstrations synthesized products containing long-chain fatty acids. These successes motivated additional effort to produce analogous molecules comprised of medium-chain fatty acids, molecules that are less common in natural oils and therefore of higher commercial value. Substantial progress has been made towards producing a subset of these chemicals, but significant work remains for most. The other primary challenge to producing oleochemicals in microbes is improving the performance, in terms of yield, rate, and titer, of biocatalysts such that economic large-scale processes are feasible. Common metabolic engineering strategies include blocking pathways that compete with synthesis of oleochemical building blocks and/or consume products, pulling flux through pathways by removing regulatory signals, pushing flux into biosynthesis by overexpressing rate-limiting enzymes, and engineering cells to tolerate the presence of oleochemical products. In this review, we describe the basic fundamentals of oleochemical synthesis and summarize advances since 2013 towards improving performance of heterotrophic microbial cell factories.
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Affiliation(s)
- Qiang Yan
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Wisconsin-Madison, Madison, WI 53706, United States; Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, United States.
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76
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Abstract
Microbial production of biofuels and bioproducts offers a sustainable and economic alternative to petroleum-based fuels and chemicals. The basidiomycete yeast Rhodosporidium toruloides is a promising platform organism for generating bioproducts due to its ability to consume a broad spectrum of carbon sources (including those derived from lignocellulosic biomass) and to naturally accumulate high levels of lipids and carotenoids, two biosynthetic pathways that can be leveraged to produce a wide range of bioproducts. While R. toruloides has great potential, it has a more limited set of tools for genetic engineering relative to more advanced yeast platform organisms such as Yarrowia lipolytica and Saccharomyces cerevisiae Significant advancements in the past few years have bolstered R. toruloides' engineering capacity. Here we expand this capacity by demonstrating the first use of CRISPR-Cas9-based gene disruption in R. toruloides Transforming a Cas9 expression cassette harboring nourseothricin resistance and selecting transformants on this antibiotic resulted in strains of R. toruloides exhibiting successful targeted disruption of the native URA3 gene. While editing efficiencies were initially low (0.002%), optimization of the cassette increased efficiencies 364-fold (to 0.6%). Applying these optimized design conditions enabled disruption of another native gene involved in carotenoid biosynthesis, CAR2, with much greater success; editing efficiencies of CAR2 deletion reached roughly 50%. Finally, we demonstrated efficient multiplexed genome editing by disrupting both CAR2 and URA3 in a single transformation. Together, our results provide a framework for applying CRISPR-Cas9 to R. toruloides that will facilitate rapid and high-throughput genome engineering in this industrially relevant organism.IMPORTANCE Microbial biofuel and bioproduct platforms provide access to clean and renewable carbon sources that are more sustainable and environmentally friendly than petroleum-based carbon sources. Furthermore, they can serve as useful conduits for the synthesis of advanced molecules that are difficult to produce through strictly chemical means. R. toruloides has emerged as a promising potential host for converting renewable lignocellulosic material into valuable fuels and chemicals. However, engineering efforts to improve the yeast's production capabilities have been impeded by a lack of advanced tools for genome engineering. While this is rapidly changing, one key tool remains unexplored in R. toruloides: CRISPR-Cas9. The results outlined here demonstrate for the first time how effective multiplexed CRISPR-Cas9 gene disruption provides a framework for other researchers to utilize this revolutionary genome-editing tool effectively in R. toruloides.
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77
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Gerritzen MJH, Martens DE, Uittenbogaard JP, Wijffels RH, Stork M. Sulfate depletion triggers overproduction of phospholipids and the release of outer membrane vesicles by Neisseria meningitidis. Sci Rep 2019; 9:4716. [PMID: 30886228 PMCID: PMC6423031 DOI: 10.1038/s41598-019-41233-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 03/05/2019] [Indexed: 12/21/2022] Open
Abstract
Outer membrane vesicles (OMVs) produced by bacteria are interesting vaccine candidates. OMVs are nanoparticles that contain many immunogenic components, are self-adjuvating, and non-replicative. Despite recent insights in the biogenesis of OMVs, there is no consensus on a conserved mechanism of OMV release and the OMV yield from bacterial cultures remains low. For Neisseria meningitidis, a Gram-negative human pathogen causing meningitis and sepsis, a feasible OMV production method based on triggering OMV release by cysteine depletion has been described. In this study, we investigated the mechanism behind this external trigger for OMV release to improve the production process. Since enhanced OMV release upon cysteine depletion was associated with oxidative stress and redox responses, we investigate the influence of more oxidized sulfur sources on OMV release. We show that N. meningitidis grows similarly on sulfate, the most oxidized sulfur source, and OMV release is triggered by sulfur depletion in general. Sulfate depletion induced increased release of OMVs over cysteine depletion. Proteomics showed that sulfur depletion resulted in oxidative stress responses and upregulated phospholipid and LPS biosynthesis. Furthermore, OMVs produced by sulfur depletion were enriched in phospholipids. Mechanistically, we hypothesize that sulfur depletion results in overproduction of phospholipids causing increased bulging of the outer membrane and subsequent OMV release.
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Affiliation(s)
- Matthias J H Gerritzen
- Institute for Translational Vaccinology (Intravacc), Process Development Bacterial Vaccines, P.O. Box 450, 3720 AL, Bilthoven, The Netherlands
- Wageningen University, Bioprocess Engineering, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Dirk E Martens
- Wageningen University, Bioprocess Engineering, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Joost P Uittenbogaard
- Institute for Translational Vaccinology (Intravacc), Analysis, Delivery, and Formulation, P.O. Box 450, 3720 AL, Bilthoven, The Netherlands
| | - René H Wijffels
- Wageningen University, Bioprocess Engineering, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- Nord University, Faculty of Biosciences and Aquaculture, P.O. Box 1409, 8049, Bodø, Norway
| | - Michiel Stork
- Institute for Translational Vaccinology (Intravacc), Process Development Bacterial Vaccines, P.O. Box 450, 3720 AL, Bilthoven, The Netherlands.
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78
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Yuan SF, Alper HS. Metabolic engineering of microbial cell factories for production of nutraceuticals. Microb Cell Fact 2019; 18:46. [PMID: 30857533 PMCID: PMC6410520 DOI: 10.1186/s12934-019-1096-y] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/27/2019] [Indexed: 11/18/2022] Open
Abstract
Metabolic engineering allows for the rewiring of basic metabolism to overproduce both native and non-native metabolites. Among these biomolecules, nutraceuticals have received considerable interest due to their health-promoting or disease-preventing properties. Likewise, microbial engineering efforts to produce these value-added nutraceuticals overcome traditional limitations of low yield from extractions and complex chemical syntheses. This review covers current strategies of metabolic engineering employed for the production of a few key nutraceuticals with selecting polyunsaturated fatty acids, polyphenolic compounds, carotenoids and non-proteinogenic amino acids as exemplary molecules. We focus on the use of both mono-culture and co-culture strategies to produce these molecules of interest. In each of these cases, metabolic engineering efforts are enabling rapid production of these molecules.
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Affiliation(s)
- Shuo-Fu Yuan
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Hal S Alper
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA.
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E Dean Keeton St. Stop C0400, Austin, TX, 78712, USA.
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79
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Wenning L, Ejsing CS, David F, Sprenger RR, Nielsen J, Siewers V. Increasing jojoba-like wax ester production in Saccharomyces cerevisiae by enhancing very long-chain, monounsaturated fatty acid synthesis. Microb Cell Fact 2019; 18:49. [PMID: 30857535 PMCID: PMC6410506 DOI: 10.1186/s12934-019-1098-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/28/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Fatty acids (FAs) with a chain length of more than 18 carbon atoms (> C18) are interesting for the production of specialty compounds derived from these FAs. These compounds include free FAs, like erucic acid (C22:1-Δ13), primary fatty alcohols (FOHs), like docosanol (C22:0-FOH), as well as jojoba-like wax esters (WEs) (C38-WE to C44-WE), which are esters of (very) long-chain FAs and (very) long-chain FOHs. In particular, FAs, FOHs and WEs are used in the production of chemicals, pharmaceuticals and cosmetic products. Jojoba seed oil is highly enriched in diunsaturated WEs with over 70 mol% being composed of C18:1-C24:1 monounsaturated FOH and monounsaturated FA moieties. In this study, we aim for the production of jojoba-like WEs in the yeast Saccharomyces cerevisiae by increasing the amount of very long-chain, monounsaturated FAs and simultaneously expressing enzymes required for WE synthesis. RESULTS We show that the combined expression of a plant-derived fatty acid elongase (FAE/KCS) from Crambe abyssinica (CaKCS) together with the yeast intrinsic fatty acid desaturase (FAD) Ole1p leads to an increase in C20:1 and C22:1 FAs in S. cerevisiae. We also demonstrate that the best enzyme candidate for C24:1 FA production in S. cerevisiae is a FAE derived from Lunaria annua (LaKCS). The combined overexpression of CaKCS and Ole1p together with a fatty acyl reductase (FAR/FAldhR) from Marinobacter aquaeolei VT8 (MaFAldhR) and a wax synthase (WS) from Simmondsia chinensis (SciWS) in a S. cerevisiae strain, overexpressing a range of other enzymes involved in FA synthesis and elongation, leads to a yeast strain capable of producing high amounts of monounsaturated FOHs (up to C22:1-FOH) as well as diunsaturated WEs (up to C46:2-WE). CONCLUSIONS Changing the FA profile of the yeast S. cerevisiae towards very long-chain monounsaturated FAs is possible by combined overexpression of endogenous and heterologous enzymes derived from various sources (e.g. a marine copepod or plants). This strategy was used to produce jojoba-like WEs in S. cerevisiae and can potentially be extended towards other commercially interesting products derived from very long-chain FAs.
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Affiliation(s)
- Leonie Wenning
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden
| | - Christer S Ejsing
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, 5230, Odense, Denmark
| | - Florian David
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden.,Biopetrolia AB, Kemivägen 10, 412 96, Gothenburg, Sweden
| | - Richard R Sprenger
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, 5230, Odense, Denmark
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, 2800, Kgs. Lyngby, Denmark
| | - Verena Siewers
- Department of Biology and Biological Engineering, Systems and Synthetic Biology, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden. .,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden.
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80
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de Paula RG, Antoniêto ACC, Ribeiro LFC, Srivastava N, O'Donovan A, Mishra PK, Gupta VK, Silva RN. Engineered microbial host selection for value-added bioproducts from lignocellulose. Biotechnol Adv 2019; 37:107347. [PMID: 30771467 DOI: 10.1016/j.biotechadv.2019.02.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 01/27/2019] [Accepted: 02/08/2019] [Indexed: 12/12/2022]
Abstract
Lignocellulose is a rich and sustainable globally available carbon source and is considered a prominent alternative raw material for producing biofuels and valuable chemical compounds. Enzymatic hydrolysis is one of the crucial steps of lignocellulose degradation. Cellulolytic and hemicellulolytic enzyme mixes produced by different microorganisms including filamentous fungi, yeasts and bacteria, are used to degrade the biomass to liberate monosaccharides and other compounds for fermentation or conversion to value-added products. During biomass pretreatment and degradation, toxic compounds are produced, and undesirable carbon catabolic repression (CCR) can occur. In order to solve this problem, microbial metabolic pathways and transcription factors involved have been investigated along with the application of protein engineering to optimize the biorefinery platform. Engineered Microorganisms have been used to produce specific enzymes to breakdown biomass polymers and metabolize sugars to produce ethanol as well other biochemical compounds. Protein engineering strategies have been used for modifying lignocellulolytic enzymes to overcome enzymatic limitations and improving both their production and functionality. Furthermore, promoters and transcription factors, which are key proteins in this process, are modified to promote microbial gene expression that allows a maximum performance of the hydrolytic enzymes for lignocellulosic degradation. The present review will present a critical discussion and highlight the aspects of the use of microorganisms to convert lignocellulose into value-added bioproduct as well combat the bottlenecks to make the biorefinery platform from lignocellulose attractive to the market.
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Affiliation(s)
- Renato Graciano de Paula
- Department of Biochemistry and Immunology, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Liliane Fraga Costa Ribeiro
- Department of Biochemistry and Immunology, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Neha Srivastava
- Department of Chemical Engineering & Technology, IIT (BHU), Varanasi 221005, U.P, India
| | - Anthonia O'Donovan
- School of Science and Computing, Galway-Mayo Institute of Technology, Galway, Ireland
| | - P K Mishra
- Department of Chemical Engineering & Technology, IIT (BHU), Varanasi 221005, U.P, India
| | - Vijai K Gupta
- ERA Chair of Green Chemistry, Department of Chemistry and Biotechnology, Tallinn University of Technology, 12618 Tallinn, Estonia.
| | - Roberto N Silva
- Department of Biochemistry and Immunology, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
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81
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Lee H, Sugiharto YEC, Lee H, Jeon W, Ahn J, Lee H. Biotransformation of dicarboxylic acids from vegetable oil–derived sources: current methods and suggestions for improvement. Appl Microbiol Biotechnol 2019; 103:1545-1555. [DOI: 10.1007/s00253-018-9571-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/07/2018] [Accepted: 12/07/2018] [Indexed: 11/28/2022]
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82
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Li F, Yang K, Xu Y, Qiao Y, Yan Y, Yan J. A genetically-encoded synthetic self-assembled multienzyme complex of lipase and P450 fatty acid decarboxylase for efficient bioproduction of fatty alkenes. BIORESOURCE TECHNOLOGY 2019; 272:451-457. [PMID: 30390537 DOI: 10.1016/j.biortech.2018.10.067] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 05/21/2023]
Abstract
We develop an efficient and economic cascade multienzymes for fatty alkene bioproduction based on the lipase hydrolysis coupled to the P450 decarboxylation in the form of multiple enzyme complex. One step preparation of a multienzyme complex was based on a mixture of cell extracts including dockerin-enzyme fusions and one cohesin-cellulose binding module (CBM) fusion through high specific interaction of dockerin and cohesin. Simultaneously, the CBM was bound to cellulose carrier to form co-immobilized multienzyme. The key factors affecting overall efficiency of alkene bioproduction including substrate channeling of hydrolysis and decarboxylation, the ratio and position of two enzymes, stability were all addressed by genetically engineering of the synthetic CBM-cohesin fusions. The multienzymes exhibited more than 9.2 fold enhancement in initial reaction rate and much higher conversion yields (69%-72%) compared to mixture of free enzyme counterpart. The enzymatic cascade based multienzymes could efficiently convert renewable triglycerides to alkenes.
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Affiliation(s)
- Fei Li
- Key Lab of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China
| | - Kaixin Yang
- Key Lab of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China
| | - Yun Xu
- Key Lab of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China
| | - Yangge Qiao
- Key Lab of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China
| | - Yunjun Yan
- Key Lab of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China
| | - Jinyong Yan
- Key Lab of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China; Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen Production and Research Base Block B, No. 9 Avenue 3 Yuexing, Yuehai Street, Nanshan District, Shenzhen 518057, China.
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83
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Fatty acid biosynthesis is enhanced in Escherichia coli strains with deletion in genes encoding the PII signaling proteins. Arch Microbiol 2018; 201:209-214. [PMID: 30506165 DOI: 10.1007/s00203-018-1603-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 11/08/2018] [Accepted: 11/24/2018] [Indexed: 10/27/2022]
Abstract
The committed and rate-limiting step in fatty acid biosynthesis is catalyzed by acetyl-CoA carboxylase (ACC). In previous studies we showed that ACC activity is inhibited through interactions with the PII signaling proteins in vitro. Here we provide in vivo support for that model; we noted that PII proteins are able to reduce malonyl-CoA levels in vivo in Escherichia coli. Furthermore, we show that fatty acid biosynthesis is strongly enhanced in E. coli strains carrying deletions in PII coding genes. Given that PII proteins act as conserved negative regulators of ACC in Bacteria, our findings may be explored to engineer other prokaryotes to improve fatty acid yields, thereby turning microbial biofuel production economically competitive in the future.
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84
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Zhang Q, You Z, Miao X. Variation of fatty acid desaturation in response to different nitrate levels in Auxenochlorella pyrenoidosa. ROYAL SOCIETY OPEN SCIENCE 2018; 5:181236. [PMID: 30564413 PMCID: PMC6281909 DOI: 10.1098/rsos.181236] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/02/2018] [Indexed: 06/09/2023]
Abstract
Microalgae are promising feedstocks for biodiesel, where the high proportion of monounsaturated fatty acid such as oleic acid (C18:1) is preferred. To regulate fatty acid desaturation in microalgae, the relationship among nitrate concentration, fatty acid composition and the expression levels of desaturase genes was explored. Dynamic variations of fatty acid profiles suggested nitrate could induce desaturation of C18 fatty acids. The content of C18:1 in Auxenochlorella pyrenoidosa was 30.88% at 0 g l-1 nitrate concentration compared with 0.48% at 1.5 g l-1. The expressions of relative delta-9, 12 and 15 fatty acid desaturase genes (Δ9, Δ12 and Δ15FADs) were further investigated. The 330% upregulated expression of Δ9FAD in logarithmic phase at 0 g l-1 resulted in C18:1 accumulation. Moreover, nitrate replenishment caused a sharp reduction of C18:1 from 34.79% to 0.22% and downregulation of Δ9FAD expression to 1% of the nitrate absence level, indicating the pivotal role of Δ9FAD in C18:1 accumulation. Finally, overexpression of Δ9FAD in Escherichia coli and Saccharomyces cerevisiae resulted in an increase of C18:1, confirming its ability of desaturating C18:0. The results could provide a new approach and scientific guidance for the improvement of biodiesel quality and industrialization of high-valued chemicals by means of metabolic engineering.
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Affiliation(s)
- Qi Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
- Biomass Energy Research Center, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zaizhi You
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
- Biomass Energy Research Center, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaoling Miao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
- Biomass Energy Research Center, Shanghai Jiao Tong University, Shanghai 200240, China
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85
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Martins-Santana L, Nora LC, Sanches-Medeiros A, Lovate GL, Cassiano MHA, Silva-Rocha R. Systems and Synthetic Biology Approaches to Engineer Fungi for Fine Chemical Production. Front Bioeng Biotechnol 2018; 6:117. [PMID: 30338257 PMCID: PMC6178918 DOI: 10.3389/fbioe.2018.00117] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 08/02/2018] [Indexed: 01/16/2023] Open
Abstract
Since the advent of systems and synthetic biology, many studies have sought to harness microbes as cell factories through genetic and metabolic engineering approaches. Yeast and filamentous fungi have been successfully harnessed to produce fine and high value-added chemical products. In this review, we present some of the most promising advances from recent years in the use of fungi for this purpose, focusing on the manipulation of fungal strains using systems and synthetic biology tools to improve metabolic flow and the flow of secondary metabolites by pathway redesign. We also review the roles of bioinformatics analysis and predictions in synthetic circuits, highlighting in silico systemic approaches to improve the efficiency of synthetic modules.
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Affiliation(s)
- Leonardo Martins-Santana
- Systems and Synthetic Biology Laboratory, Cell and Molecular Biology Department, Ribeirão Preto Medical School, São Paulo University (FMRP-USP), Ribeirão Preto, Brazil
| | - Luisa C Nora
- Systems and Synthetic Biology Laboratory, Cell and Molecular Biology Department, Ribeirão Preto Medical School, São Paulo University (FMRP-USP), Ribeirão Preto, Brazil
| | - Ananda Sanches-Medeiros
- Systems and Synthetic Biology Laboratory, Cell and Molecular Biology Department, Ribeirão Preto Medical School, São Paulo University (FMRP-USP), Ribeirão Preto, Brazil
| | - Gabriel L Lovate
- Systems and Synthetic Biology Laboratory, Cell and Molecular Biology Department, Ribeirão Preto Medical School, São Paulo University (FMRP-USP), Ribeirão Preto, Brazil
| | - Murilo H A Cassiano
- Systems and Synthetic Biology Laboratory, Cell and Molecular Biology Department, Ribeirão Preto Medical School, São Paulo University (FMRP-USP), Ribeirão Preto, Brazil
| | - Rafael Silva-Rocha
- Systems and Synthetic Biology Laboratory, Cell and Molecular Biology Department, Ribeirão Preto Medical School, São Paulo University (FMRP-USP), Ribeirão Preto, Brazil
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86
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Santala S, Efimova E, Santala V. Dynamic decoupling of biomass and wax ester biosynthesis in Acinetobacter baylyi by an autonomously regulated switch. Metab Eng Commun 2018; 7:e00078. [PMID: 30271720 PMCID: PMC6158957 DOI: 10.1016/j.mec.2018.e00078] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/13/2018] [Accepted: 09/16/2018] [Indexed: 01/09/2023] Open
Abstract
For improving the microbial production of fuels and chemicals, gene knock-outs and overexpression are routinely applied to intensify the carbon flow from substrate to product. However, their possibilities in dynamic control of the flux between the biomass and product synthesis are limited, whereas dynamic metabolic switches can be used for optimizing the distribution of carbon and resources. The production of single cell oils is especially challenging, as the synthesis is strictly regulated, competes directly with biomass, and requires defined conditions, such as nitrogen limitation. Here, we engineered a metabolic switch for redirecting carbon flow from biomass to wax ester production in Acinetobacter baylyi ADP1 using acetate as a carbon source. Isocitrate lyase, an essential enzyme for growth on acetate, was expressed under an arabinose inducible promoter. The autonomous downregulation of the expression is based on the gradual oxidation of the arabinose inducer by a glucose dehydrogenase gcd. The depletion of the inducer, occurring simultaneously to acetate consumption, switches the cells from a biomass mode to a lipid synthesis mode, enabling the efficient channelling of carbon to wax esters in a simple batch culture. In the engineered strain, the yield and titer of wax esters were improved by 3.8 and 3.1 folds, respectively, over the control strain. In addition, the engineered strain accumulated wax esters 19% of cell dry weight, being the highest reported among microbes. The study provides important insights into the dynamic engineering of the biomass-dependent synthesis pathways for the improved production of biocompounds from low-cost and sustainable substrates. Efficient conversion of acetate to storage lipids (wax ester) is demonstrated. AraC-pBAD promoter coupled with glucose dehydrogenase was used as a dynamic switch. The autonomous switch allowed dynamic shift from biomass to lipid synthesis mode. Wax ester yield and titer were improved by 3–4 folds over the wild type strain. The highest amount of wax esters produced in microbes, 19% of CDW, was achieved.
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Affiliation(s)
- Suvi Santala
- Laboratory of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, FI-33720, Tampere, Finland
| | - Elena Efimova
- Laboratory of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, FI-33720, Tampere, Finland
| | - Ville Santala
- Laboratory of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, FI-33720, Tampere, Finland
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