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1.
Chemosphere ; 361: 142527, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38838866

ABSTRACT

Peri-urban environments are significant reservoirs of wastewater, and releasing this untreated wastewater from these resources poses severe environmental and ecological threats. Wastewater mitigation through sustainable approaches is an emerging area of interest. Algae offers a promising strategy for carbon-neutral valorization and recycling of urban wastewater. Aiming to provide a proof-of-concept for complete valorization and recycling of urban wastewater in a peri-urban environment in a closed loop system, a newly isolated biocrust-forming cyanobacterium Desertifilum tharense BERC-3 was evaluated. Here, the highest growth and lipids productivity were achieved in urban wastewater compared to BG11 and synthetic wastewater. D. tharense BERC-3 showed 60-95% resource recovery efficiency and decreased total dissolved solids, chemical oxygen demand, biological oxygen demand, nitrate nitrogen, ammonia nitrogen and total phosphorus contents of the water by 60.37%, 81.11%, 82.75%, 87.91%, 85.13%, 85.41%, 95.87%, respectively, making it fit for agriculture as per WHO's safety limits. Soil supplementation with 2% wastewater-cultivated algae as a soil amender, along with its irrigation with post-treated wastewater, improved the nitrogen content and microbial activity of the soil by 0.3-2.0-fold and 0.5-fold, respectively. Besides, the availability of phosphorus was also improved by 1.66-fold. The complete bioprocessing pipeline offered a complete biomass utilization. This study demonstrated the first proof-of-concept of integrating resource recovery and resource recycling using cyanobacteria to develop a peri-urban algae farming system. This can lead to establishing wastewater-driven algae cultivation systems as novel enterprises for rural migrants moving to urban areas.


Subject(s)
Cyanobacteria , Phosphorus , Waste Disposal, Fluid , Wastewater , Wastewater/chemistry , Phosphorus/analysis , Waste Disposal, Fluid/methods , Cyanobacteria/growth & development , Nitrogen/analysis , Recycling , Agriculture/methods , Biological Oxygen Demand Analysis , Soil/chemistry
2.
J Agric Food Chem ; 72(8): 3846-3871, 2024 Feb 28.
Article in English | MEDLINE | ID: mdl-38372640

ABSTRACT

Methylated natural products are widely spread in nature. S-Adenosyl-l-methionine (SAM) is the secondary abundant cofactor and the primary methyl donor, which confer natural products with structural and functional diversification. The increasing demand for SAM-dependent natural products (SdNPs) has motivated the development of microbial cell factories (MCFs) for sustainable and efficient SdNP production. Insufficient and unsustainable SAM availability hinders the improvement of SdNP MCF performance. From the perspective of developing MCF, this review summarized recent understanding of de novo SAM biosynthesis and its regulatory mechanism. SAM is just the methyl mediator but not the original methyl source. Effective and sustainable methyl source supply is critical for efficient SdNP production. We compared and discussed the innate and relatively less explored alternative methyl sources and identified the one involving cheap one-carbon compound as more promising. The SAM biosynthesis is synergistically regulated on multilevels and is tightly connected with ATP and NAD(P)H pools. We also covered the recent advancement of metabolic engineering in improving intracellular SAM availability and SdNP production. Dynamic regulation is a promising strategy to achieve accurate and dynamic fine-tuning of intracellular SAM pool size. Finally, we discussed the design and engineering constraints underlying construction of SAM-responsive genetic circuits and envisioned their future applications in developing SdNP MCFs.


Subject(s)
Biological Products , S-Adenosylmethionine , S-Adenosylmethionine/metabolism , Metabolic Engineering
3.
Sci Total Environ ; 920: 171034, 2024 Apr 10.
Article in English | MEDLINE | ID: mdl-38369147

ABSTRACT

Straw is a typical biomass resource which can be converted into high nutritional value feed via microbial fermentation. The degradation and conversion of straw using a synthetic microbial community (SMC-8) was functionally investigated to characterise its nitrogen conversion and carbon metabolism. Four species of bacteria were found to utilise >20 % of the inorganic nitrogen within 15 h, and the ratio of the diameter of fungal transparent circles (D) to the diameter of the colony (d) of the four fungal species was >1. Solid-state fermentation of corn straw increased the total amino acid (AA) content by 41.69 %. The absolute digestibility of fermented corn straw dry weight (DW) and true protein was 34.34 % and 45.29 %, respectively. Comprehensive analysis of functional proteins revealed that Aspergillus niger, Trichoderma viride, Cladosporium cladosporioides, Bacillus subtilis and Acinetobacter johnsonii produce a complex enzyme system during corn straw fermentation, which plays a key role in the degradation of lignocellulose. This study provided a new insight in utilizing corn straw.


Subject(s)
Bacillus subtilis , Zea mays , Fermentation , Nitrogen , Animal Feed/analysis
4.
Biotechnol Lett ; 46(1): 55-68, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38064040

ABSTRACT

OBJECTIVES: Enhance the androstadienedione (Androst-1,4-diene-3,17-dione, ADD) production of rough morphotype Mycolicibacterium neoaurum R by repeated-batch fermentation of immobilized cells. RESULTS: M. neoaurum R was a rough colony morphotype variant, obtained from the routine plating of smooth M. neoaurum strain CICC 21097. M. neoaurum R showed rougher cell surface and aggregated in broth. The ADD production of M. neoaurum R was notably lower than that of M. neoaurum CICC 21097 during the free cell fermentation, but the yield gap could be erased after proper cell immobilization. Subsequently, repeated-batch fermentation of immobilized M. neoaurum R was performed to shorten the production cycle and enhance the bio-production efficiency of ADD. Through the optimization of the immobilization carriers and the co-solvents for phytosterols, the ADD productivity of M. neoaurum R immobilized by semi-expanded perlite reached 0.075 g/L/h during the repeated-batch fermentation for 40 days. CONCLUSIONS: The ADD production of the rough-type M. neoaurum R was notably enhanced by the immobilization onto semi-expanded perlite. Moreover, the ADD batch yields of M. neoaurum R immobilized by semi-expanded perlite were maintained at high levels during the repeated-batch fermentation.


Subject(s)
Mycobacteriaceae , Phytosterols , Silicon Dioxide , Phytosterols/metabolism , Mycobacteriaceae/metabolism , Aluminum Oxide/metabolism
6.
Polymers (Basel) ; 15(9)2023 Apr 23.
Article in English | MEDLINE | ID: mdl-37177139

ABSTRACT

A water-soluble cationic kraft lignin (named JLQKL50), synthesized by combining quaternization and crosslinking reactions, was used as an additive to enhance the enzymatic hydrolysis of dilute-alkali-pretreated corn stalk. The chemical constitution of JLQKL50 was investigated by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR) and 13C NMR spectroscopy, and elemental analysis. The enzymatic hydrolysis efficiency of corn stalk at solid content of 10% (w/v) was significantly improved from 70.67% to 78.88% after 24 h when JLQKL50 was added at a concentration of 2 g/L. Meanwhile, the enzymatic hydrolysis efficiency after 72 h reached 91.11% with 10 FPU/g of cellulase and 97.92% with 15 FPU/g of cellulase. In addition, JLQKL50 was found capable of extending the pH and temperature ranges of enzymatic hydrolysis to maintain high efficiency (higher than 70%). The decrease in cellulase activity under vigorous stirring with the addition of JLQKL50 was 17.4%, which was much lower than that (29.7%) without JLQKL50. The addition of JLQKL50 reduced the nonproductive adsorption of cellulase on the lignin substrate and improved the longevity, dispersity, and stability of the cellulase by enabling electrostatic repulsion. Therefore, the enzymatic hydrolysis of the corn stalk was enhanced. This study paves the way for the design of sustainable lignin-based additives to boost the enzymatic hydrolysis of lignocellulosic biomass.

7.
Biotechnol J ; 18(7): e2200600, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37079661

ABSTRACT

d-Allulose has many health-benefiting properties and therefore sustainably applied in food, pharmaceutical, and nutrition industries. The aldol reaction-based route is a very promising alternative to Izumoring strategy in d-allulose production. Remarkable studies reported in the past cannot get rid of by-product formation and costly purified enzyme usage. In the present study, we explored the glycerol assimilation by modularly assembling the d-allulose synthetic cascade in Escherichia coli envelop. We achieved an efficient whole-cell catalyst that produces only d-allulose from cheap glycerol feedstock, eliminating the involvement of purified enzymes. Detailed process optimization improved the d-allulose titer by 1500.00%. Finally, the production was validated in 3-L scale using a 5-L fermenter, and 5.67 g L-1 d-allulose was produced with a molar yield of 31.43%.


Subject(s)
Glycerol , Racemases and Epimerases , Catalysis , Fructose , Escherichia coli/genetics
8.
Front Bioeng Biotechnol ; 11: 1156953, 2023.
Article in English | MEDLINE | ID: mdl-36911188

ABSTRACT

D-allulose is a high-value rare sugar with many health benefits. D-allulose market demand increased dramatically after approved as generally recognized as safe (GRAS). The current studies are predominantly focusing on producing D-allulose from either D-glucose or D-fructose, which may compete foods against human. The corn stalk (CS) is one of the main agricultural waste biomass in the worldwide. Bioconversion is one of the promising approach to CS valorization, which is of significance for both food safety and reducing carbon emission. In this study, we tried to explore a non-food based route by integrating CS hydrolysis with D-allulose production. Firstly we developed an efficient Escherichia coli whole-cell catalyst to produce D-allulose from D-glucose. Next we hydrolyzed CS and achieved D-allulose production from the CS hydrolysate. Finally we immobilized the whole-cell catalyst by designing a microfluidic device. Process optimization improved D-allulose titer by 8.61 times, reaching 8.78 g/L from CS hydrolysate. With this method, 1 kg CS was finally converted to 48.87 g D-allulose. This study validated the feasibility of valorizing corn stalk by converting it to D-allulose.

9.
Enzyme Microb Technol ; 156: 109991, 2022 May.
Article in English | MEDLINE | ID: mdl-35151990

ABSTRACT

Flavonoids are a group of valuable compounds with a variety of health benefits. (2 S)-Naringenin is an important flavonoid skeleton, which can be tailored into almost all flavonoids. In this study, the Saccharomyces cerevisiae native precursor pathways were explored and higher-active CHSs from plants rich in flavonoids were screened. The results indicated that overexpressing the native precursor pathways is not an efficient approach to improving (2 S)-naringenin production in our chassis strain. On the other hand, by screening from plants rich in flavonoids, we obtained four CHSs with higher activities than the commonly used PhCHS. Among these CHSs, SjCHS1 increased the (2 S)-naringenin titer by 48.38% in shaking flasks. Finally, we combined the native precursor pathways optimization with the higher-active CHS that screened, and further increased the (2 S)-naringenin titer to 203.49 mg/L from glucose in shaking flasks. The results achieved in this study indicated that plants rich in flavonoids are good sources for higher-active CHS screening, and that the heterologous pathway and chassis precursor flux should be synergistically engineered to achieve higher production.


Subject(s)
Chalcones , Flavanones , Chalcones/metabolism , Flavanones/metabolism , Flavonoids/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism
10.
Biotechnol Adv ; 53: 107860, 2021 12.
Article in English | MEDLINE | ID: mdl-34710554

ABSTRACT

Steroid-based drugs have been developed as the second largest medical category in pharmaceutics. The well-established route of steroid industry includes two steps: the conversion of natural products with a steroid framework to steroid-based drug intermediates and the synthesis of varied steroid-based drugs from steroid-based drug intermediates. The biosynthesis of steroid-based drug intermediates from phytosterols by Mycolicibacterium cell factories bypasses the potential undersupply of diosgenin in the traditional steroid chemical industry. Moreover, the biosynthesis route shows advantages on multiple steroid-based drug intermediate products, more ecofriendly processes, and consecutive reactions carried out in one operation step and in one pot. Androsta-4-ene-3,17-dione (AD), androsta-1,4-diene-3,17-dione (ADD) and 9-hydroxyandrostra-4-ene-3,17-dione (9-OH-AD) are the representative steroid-based drug intermediates synthesized by mycolicibacteria. Other steroid metabolites of mycolicibacteria, like 4-androstene-17ß-ol-3-one (TS), 22-hydroxy-23,24-bisnorchol-4-ene-3-one (4-HBC), 22-hydroxy-23,24-bisnorchol-1,4-diene-3-one (1,4-HBC), 9,22-dihydroxy-23,24-bisnorchol-4-ene-3-one (9-OH-HBC), 3aα-H-4α-(3'-propionic acid)-7aß-methylhexahydro-1,5-indanedione (HIP) and 3aα-H-4α-(3'-propionic acid)-5α-hydroxy-7aß-methylhexahydro-1-indanone-δ-lactone (HIL), also show values as steroid-based drug intermediates. To improve the bio-production efficiency of the steroid-based drug intermediates, mycolicibacterial strains and biotransformation processes have been continuously studied in the past decades. Many mycolicibacteria that accumulate steroid drug intermediates have been isolated, and subsequently optimized by conventional mutagenesis and genetic engineering. Especially, with the clarification of the mycolicibacterial steroid metabolic pathway and the developments on gene editing technologies, rational design is becoming an important measure for the construction and optimization of engineered mycolicibacteria strains that produce steroid-based drug intermediates. Hence, by reviewing researches in the past two decades, this article updates the overall process of steroid metabolism in mycolicibacteria and provides comprehensive schemes for the rational construction of mycolicibacterial strains that accumulate steroid-based drug intermediates. In addition, the special strategies for the bioconversion of highly hydrophobic steroid in aqueous media are discussed as well.


Subject(s)
Pharmaceutical Preparations , Phytosterols , Biotransformation , Metabolic Networks and Pathways , Phytosterols/metabolism , Steroids
11.
Front Bioeng Biotechnol ; 9: 648382, 2021.
Article in English | MEDLINE | ID: mdl-33777917

ABSTRACT

The sugar alcohols and functional sugars have wide applications in food, pharmaceutical, and chemical industries. However, the smaller quantities of natural occurring sugar alcohols and functional sugars restricted their applications. The enzymatic and whole-cell catalyst production is emerging as the predominant alternatives. The properties of Yarrowia lipolytica make it a promising sugar alcohol and functional sugar producer. However, there are still some issues to be resolved. As there exist reviews about the chemical structures, physicochemical properties, biological functions, applications, and biosynthesis of sugar alcohols and/or functional sugars in Y. lipolytica, this mini review will not only update the recent advances in enzymatic and microbial production of sugar alcohols (erythritol, D-threitol, and xylitol) and functional sugars (isomaltulose, trehalose, fructo-oligosaccharides, and galacto-oligosaccharides) by using recombinant Y. lipolytica but also focus on the studies of gene discovery, pathway engineering, expanding substrate scope, bioprocess engineering, and novel breeding methods to resolve the aforementioned issues.

12.
RSC Adv ; 11(56): 35280-35286, 2021 Oct 28.
Article in English | MEDLINE | ID: mdl-35493134

ABSTRACT

Zn/MnO2 batteries, one of the most widely studied rechargeable aqueous zinc-ion batteries, suffer from poor cyclability because the structure of MnO2 is labile with cycling. Herein, the structural stability of α-MnO2 is enhanced by simultaneous Al3+ doping and lignin coating during the formation of α-MnO2 crystals in a hydrothermal process. Al3+ enters the [MnO6] octahedron accompanied by producing oxygen vacancies, and lignin further stabilizes the doped Al3+ via strong interaction in the prepared material, Al-doped α-MnO2 coated by lignin (L + Al@α-MnO2). Meanwhile, the conductivity of L + Al@α-MnO2 improves due to Al3+ doping, and the surface area of L + Al@α-MnO2 increases because of the production of nanorod structures after Al3+ doping and lignin coating. Compared with the reference α-MnO2 cathode, the L + Al@α-MnO2 cathode achieves superior performance with durably high reversible capacity (∼180 mA h g-1 at 1.5 A g-1) and good cycle stability. In addition, ex situ X-ray diffraction characterization of the cathode at different voltages in the first cycle is employed to study the related mechanism on improving battery performance. This study may provide ideas of designing advanced cathode materials for other aqueous metal-ion batteries.

13.
Metab Eng ; 61: 79-88, 2020 09.
Article in English | MEDLINE | ID: mdl-32445959

ABSTRACT

Metabolic addiction, an organism that is metabolically addicted with a compound to maintain its growth fitness, is an underexplored area in metabolic engineering. Microbes with heavily engineered pathways or genetic circuits tend to experience metabolic burden leading to degenerated or abortive production phenotype during long-term cultivation or scale-up. A promising solution to combat metabolic instability is to tie up the end-product with an intermediary metabolite that is essential to the growth of the producing host. Here we present a simple strategy to improve both metabolic stability and pathway yield by coupling chemical addiction with negative autoregulatory genetic circuits. Naringenin and lipids compete for the same precursor malonyl-CoA with inversed pathway yield in oleaginous yeast. Negative autoregulation of the lipogenic pathways, enabled by CRISPRi and fatty acid-inducible promoters, repartitions malonyl-CoA to favor flavonoid synthesis and increased naringenin production by 74.8%. With flavonoid-sensing transcriptional activator FdeR and yeast hybrid promoters to control leucine synthesis and cell grwoth fitness, this amino acid feedforward metabolic circuit confers a flavonoid addiction phenotype that selectively enrich the naringenin-producing pupulation in the leucine auxotrophic yeast. The engineered yeast persisted 90.9% of naringenin titer up to 324 generations. Cells without flavonoid addiction regained growth fitness but lost 94.5% of the naringenin titer after cell passage beyond 300 generations. Metabolic addiction and negative autoregulation may be generalized as basic tools to eliminate metabolic heterogeneity, improve strain stability and pathway yield in long-term and large-scale bioproduction.


Subject(s)
Homeostasis , Metabolic Engineering , Yarrowia , Malonyl Coenzyme A/genetics , Malonyl Coenzyme A/metabolism , Yarrowia/genetics , Yarrowia/metabolism
14.
ACS Synth Biol ; 8(11): 2514-2523, 2019 11 15.
Article in English | MEDLINE | ID: mdl-31622552

ABSTRACT

Plants possess myriads of secondary metabolites with a broad spectrum of health-promoting benefits. To date, plant extraction is still the primary route to produce high-value natural products which inherently suffers from economics and scalability issues. Heterologous expression of plant biosynthetic gene clusters in microbial host is considered as a feasible approach to overcoming these limitations. Oleaginous yeast produces a large amount of lipid bodies, the abundant membrane structure and the lipophilic environment provide the ideal environment for the regioselectivity and stereoselectivity of many plant-derived P450 enzymes. In this work, we used modular method to construct, characterize, and optimize the flavonoid pathways in Yarrowia lipolytica. We also evaluated various precursor biosynthetic routes and unleashed the metabolic potential of Y. lipolytica to produce flavonoids and hydroxylated flavonoids. Specifically, we have identified that chalcone synthase (CHS) and cytochrome P450 reductases (CPR) were the bottlenecks of hydroxylated flavonoid production. We determined the optimal gene copy number of CHS and CPR to be 5 and 2, respectively. We further removed precursor pathway limitations by expressing genes associated with chorismate and malonyl-CoA supply. With pH and carbon-nitrogen ratio (C/N) optimization, our engineered strain produced 252.4 mg/L naringenin, 134.2 mg/L eriodictyol, and 110.5 mg/L taxifolin from glucose in shake flasks. Flavonoid and its hydroxylated derivatives are most prominently known as antioxidant and antiaging agents. These findings demonstrate our ability to harness the oleaginous yeast as the microbial workhorse to expand nature's biosynthetic potential, enabling us to bridge the gap between drug discovery and natural product manufacturing.


Subject(s)
Bioreactors , Flavanones/biosynthesis , Metabolic Engineering/methods , Quercetin/analogs & derivatives , Yarrowia/genetics , Yarrowia/metabolism , Acyltransferases/genetics , Chorismic Acid/genetics , Chorismic Acid/metabolism , Gene Expression , Glucose/metabolism , Hydrogen-Ion Concentration , Hydroxylation , Malonyl Coenzyme A/genetics , Malonyl Coenzyme A/metabolism , NADPH-Ferrihemoprotein Reductase/genetics , Quercetin/biosynthesis , Sulfuric Acids/metabolism , Synthetic Biology/methods
15.
Bioresour Technol ; 294: 122219, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31610487

ABSTRACT

Scenedesmus raciborskii WZKMT was subjected to fed-batch enzymatic hydrolysis and fermentation to facilitate the saccharification of high-solid-loading substrate for high-concentration ethanol. In this work, process factors affecting enzymatic hydrolysis, including enzyme loading, temperature, pH, and solid loading, were optimized. Results showed that 58.03 g L-1 glucose, 12.57 g L-1 xylose, and 1.45 g L-1 cellobiose were obtained after the enzymatic hydrolysis of 330 g L-1 substrates under the optimal conditions of 30 FPU g-1 enzyme loading, 50 °C, and pH 5.5. Meanwhile, 89.60% yield and 30.43 g L-1 content of ethanol were obtained after the fermentation of 330 g L-1 hydrolysate. The maximum ethanol concentration of 79.38 g L-1 could be achieved through repeated fed-batch process, indicating that S. raciborskii WZKMT is a promising feedstock for ethanol production.


Subject(s)
Ethanol , Scenedesmus , Biofuels , Biomass , Fermentation , Hydrolysis , Saccharomyces cerevisiae
16.
Metab Eng ; 54: 109-116, 2019 07.
Article in English | MEDLINE | ID: mdl-30940507

ABSTRACT

Metabolic engineering entails target modification of cell metabolism to maximize cell's production potential. Due to the complexity of cell metabolism, feedback genetic circuits have emerged as basic tools to combat metabolic heterogeneity, enhance microbial cooperation as well as boost cell's productivity. This is generally achieved by applying social reward-punishment rules to eliminate cheaters and reward winners in a mixed cell population. With metabolite-responsive transcriptional factors to rewire gene expression, metabolic engineers are well-positioned to integrate feedback genetic circuits with growth fitness and achieve dynamic population control. Towards this goal, we argue that feedback genetic circuits and microbial interactions will be a golden mine for future metabolic engineering. We will summarize the design principles of engineering burden-driven feedback control to combat metabolic stress, implementing population quality control to eliminate cheater cell, applying product addiction to reward productive cell, as well as layering dual dynamic regulation to decouple cell growth from product formation. Collectively, these strategies will be useful to improve community-level cellular performance. Encoding such decision-marking functions and reprogramming cellular logics at population level will enable metabolic engineers to deliver robust cell factories and pave the way for intelligent bioproduction. We envision that various cellular regulation mechanisms and genetic/metabolic circuits could be exploited to achieve self-adaptive or autonomous metabolic function for diverse biotechnological and medical applications. Applying these design rules may offer us a genetic solution beyond bioprocess engineering strategies to further improve the cost-competitiveness of industrial fermentation.


Subject(s)
Biotechnology , Gene Regulatory Networks , Metabolic Engineering , Models, Biological
17.
ACS Synth Biol ; 8(3): 568-576, 2019 03 15.
Article in English | MEDLINE | ID: mdl-30695641

ABSTRACT

Conventional plasmid-based gene expression tends to introduce genetic instability and gene copy number variations that lead to degenerated production. The limited number of auxotrophic markers in Yarrowia lipolytica also restricts our ability to perform iterative genetic modifications and manipulate long gene clusters. To overcome these limitations, we combined the high recombination efficiency of the Cre-loxP system and the high integration rate of 26s rDNA, and developed a versatile framework to iteratively integrate multicopy metabolic pathways in Y. lipolytica. We demonstrated the efficient genome integration of a plant-derived flavonoid pathway at random sites with multiple copies. Transient expression of Cre recombinase enabled efficient marker removal and allowed for the next round of genome integration. Investigating the recombination events demonstrated that the iterative integration is happening at sufficiently high rates (more than 80%) without disrupting the previous integration. Both the flavonoid precursor pathway and the plant-derived cytochrome c P450 enzymes were functionally integrated to improve flavonoid and hydroxylated flavonoid production. The engineered strains produced 71.2 mg/L naringenin, 54.2 mg/L eriodyctiol, and 48.1 mg/L taxifolin. The reported work provides a versatile platform to iteratively integrate functional gene clusters at high copy numbers. This work may streamline and expand our capability to build efficient microbial cell factories for high-value natural products and commodity chemical production in Y. lipolytica.


Subject(s)
DNA, Ribosomal/genetics , Genetic Engineering/methods , Integrases/genetics , Metabolic Networks and Pathways/genetics , Yarrowia/genetics , Yarrowia/metabolism , Cytochrome P-450 Enzyme System/metabolism , DNA Copy Number Variations , Escherichia coli/genetics , Flavanones/biosynthesis , Gene Dosage , Genetic Vectors , Genomic Instability , Hydroxylation , Multigene Family , Plasmids/genetics , Quercetin/analogs & derivatives , Quercetin/biosynthesis
18.
Bioresour Technol ; 267: 578-583, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30055475

ABSTRACT

Coniferyl alcohol is a valuable chemical. However, the current approaches to obtain coniferyl alcohol are either unefficient or expensive. Penicillium simplicissimum vanillyl alcohol oxidase (PsVAO) can be used to produce coniferyl alcohol. However, PsVAO intrinsically produces harmful byproduct H2O2. Utilizing catalase to decompose H2O2 is a potential straightforward approach; however, catalase can also exhibit peroxidase activity to facilitate coniferyl alcohol over-oxidation. In this study, catalases exhibiting both high catalase activity and low peroxidase activity were found out, and introduced into the bioconversion systems. Our results showed that eliminating H2O2in situ released H2O2 inhibition of PsVAO, improved coniferyl alcohol production and eliminated coniferyl alcohol over-oxidation. Finally, coniferyl alcohol titer, molar yield, and productivity reached 22.9 g/L, 78.7%, and 0.5 g/(L × h) respectively. An efficient coniferyl alcohol production method was developed by overcoming the intrinsic disadvantages of PsVAO.


Subject(s)
Eugenol/metabolism , Hydrogen Peroxide/chemistry , Phenols , Oxidation-Reduction
19.
Plant J ; 92(6): 995-1004, 2017 Dec.
Article in English | MEDLINE | ID: mdl-28990236

ABSTRACT

Silymarin is a collection of compounds extracted from the medicinal herb milk thistle, among which silybin is the major flavonolignan. However, the biosynthesis pathway of silybin remains unclear. In this study, biomimetic reactions demonstrated that silybin can be synthesized from coniferyl alcohol and taxifolin by the action of peroxidase. The concentration profiles of silybin and its precursors and RNA-Seq analysis of gene expression revealed that the amount of taxifolin and the activity of peroxidase serve as the limiting factors in silybin biosynthesis. Hierarchical clustering of the expression profile of genes of the flavonoid biosynthesis pathway distinguished flowers from other organs. RNA-Seq revealed five candidates for the peroxidase involved in silybin production, among which APX1 (ascorbate peroxidase 1) showed a distinct peroxidase activity and the capacity to synthesize silybin. The spatial organization of silybin biosynthesis in milk thistle was elucidated, which could help our understanding of the biosynthesis of silybin and other flavonolignans.


Subject(s)
Antioxidants/metabolism , Silybum marianum/genetics , Silymarin/metabolism , Transcriptome , Biosynthetic Pathways , Flowers/genetics , Flowers/metabolism , Silybum marianum/metabolism , Plants, Medicinal , Silybin
20.
Biotechnol Bioeng ; 114(9): 2066-2074, 2017 09.
Article in English | MEDLINE | ID: mdl-28436004

ABSTRACT

Pinoresinol is a natural lignan with a high market value that has potential pharmacological and food supplement applications. Pinoresinol is currently isolated from plants, which suffers from low efficiency and yield. To produce pinoresinol from inexpensive and industrially available eugenol, an in vivo enzymatic cascade composed of vanillyl alcohol oxidase and peroxidase was designed, which scavenges H2 O2 automatically and eliminates protein purification and cofactor addition. Two peroxidases were screened and identified from Escherichia coli BL21 (DE3), and tested in the enzymatic cascade. To balance the flux, different genetic architectures were constructed by using ePathBrick and fusion gene approaches. Scavenging H2 O2 alleviated by-product toxicity and enzyme inhibition, and led to efficient pinoresinol production. Optimization of the reaction conditions achieved a titer of 11.29 g/L pinoresinol. The molar yield and productivity were 52.77% and 1.03 g/(L × h), respectively. The elegant strategy developed herein utilizes the harmful by-product to drive the biosynthetic reaction forward and simultaneously detoxify cells, thereby preventing enzyme inhibition. Biotechnol. Bioeng. 2017;114: 2066-2074. © 2017 Wiley Periodicals, Inc.


Subject(s)
Escherichia coli/physiology , Free Radical Scavengers/metabolism , Genetic Enhancement/methods , Hydrogen Peroxide/metabolism , Lignans/biosynthesis , Metabolic Engineering/methods , Peroxidases/metabolism , Furans/isolation & purification , Lignans/isolation & purification , Peroxidases/genetics
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