A biofuel cell harvesting energy from glucose-air and fruit juice-air

The membraneless biofuel cell (BFC) is facile prepared based on glucose oxidase and laccase as anodic and cathodic catalyst, respectively, by using 1,1'-dicarboxyferrocene as the mediators of both anode and cathode. The BFC can work by taking glucose as fuel in air-saturated solution, in which air serves as the oxidizer of the cathode. More interestingly, the fruit juice containing glucose, e.g. grape, banana or orange juice as the fuels substituting for glucose can make the BFC work. The BFC shows several advantages which have not been reported to our knowledge: (1) it is membraneless BFC which can work with same mediator on both anode and cathode; (2) fruit juice can act as fuels of BFCs substituting for usually used glucose; (3) especially, the orange juice can greatly enhance the power output rather than that of glucose, grape or banana juice. Besides, the facile and simple preparation procedure and easy accessibility of fruit juice as well as air being whenever and everywhere imply that our system has promising potential for the development and practical application of BFCs.     

High-performance bioanode based on the composite of CNTs-immobilized mediator and silk film-immobilized glucose oxidase for glucose/O2 biofuel cells

A high-performance bioanode based on the composite of carbon nanotubes (CNTs)-immobilized mediator and silk film (SF)-immobilized glucose oxidase (GOD) was developed for glucose/O(2) biofuel cell (BFC). Ferrocenecarboxaldehyde (Fc) was used as the mediator and covalently immobilized on the ethylenediamine (EDA)-functionalized CNTs (CNTs-EDA). GOD was cross-linked on the SF with glutaraldehyde (GA) as the cross-linking agent. The resulting electrode (CNTs-Fc/SF-GOD/glassy carbon (GC) electrode) exhibited good catalytic activity towards glucose oxidation and excellent stability. For the assembled glucose/O(2) BFC with the CNTs-Fc/SF-GOD/GC electrode as the bioanode and a commercial E-TEK Pt/C modified GC electrode as the cathode, the open circuit potential is 0.48 V and the maximum power density of 50.70 μW cm(-2) can be achieved at 0.15 V.     

Continuous production of monoacylglycerols from palm olein in packed-bed reactor with immobilized lipase PS

A packed-bed reactor (PBR) system using immobilized lipase PS as biocatalyst was developed for continuous monoacylglycerols (MAG) production. The condition for continuous MAG production using immobilized lipase PS (IM-PS) of 1.5 g (550 U) in PBR (0.68 cm i.d., 25 cm long) was optimized. The effect of molar ratio of glycerol to palm olein, water content in glycerol and residence time on MAG production was investigated. The optimal glycerol to palm olein molar ratio and water content in glycerol were 12:1 and 10% (w/w), respectively. The yield of MAG increased with increasing residence time. At a residence time of 7.5 h gave the highest yield of MAG of 60%. The long-term operation gave the highest yield of MAG 61.5% at 24 h of the operation time with the productivity of 1.61 g MAG/day. A half-life of the long-term process was 35 days of the operation time with the productivity of 0.81 g MAG/day. Furthermore, the large scale of MAG production was performed continuously with IM-PS of 15 g (5500 U) in PBR (1.5 cm i.d., 50 cm long). The highest yield of MAG in large-scale operation of 70.1% and the 11-fold increasing in productivity of 18.3 g MAG/day were obtained at 24 h of the operation time.     

High-performance amperometric biosensors and biofuel cell based on chitosan-strengthened cast thin films of chemically synthesized catecholamine polymers with glucose oxidase effectively entrapped

Rapid oxidation of dopamine (DA) or L-noradrenaline (NA) by K(3)Fe(CN)(6) yields poly(DA) (PDA(C)) or poly(NA) (PNA(C)) with glucose oxidase (GOx) effectively entrapped, and such an enzyme-entrapped catecholamine polymer is cast on an Au electrode followed by chitosan (CS) strengthening for biosensing and fabrication of a biofuel cell (BFC). The optimized glucose biosensor of CS/PDA(C)-GOx/Au displays an extremely high sensitivity up to 135 μA mM(-1) cm(-2), a very low limit of detection of 0.07 μM, a response time of <3 s, good suppression of interferents, striking thermostability (lifetime of 3 weeks at 60°C and over 2 months at 30°C), and high resistance to urea denaturation. The biosensor also works well in the second generation biosensing mode with p-benzoquinone (BQ) or ferrocene monocarboxylic acid (Fc) as an artificial mediator, with greatly broadened linear detection ranges (2.0 μM-48.0 mM for BQ and 2.0 μM-16.0 mM for Fc) and up to mA cm(-2)-scale glucose-saturated current density. The good permeability of artificial mediators across the enzyme film enables the quantification of the surface concentration of immobilized GOx on the basis of a reported kinetic model, and UV-Vis spectrophotometry is used to measure the enzymatic activity, revealing high enzymatic activity/load at CS/PDA(C)-GOx/Au. A BFC is also successfully fabricated with a bioanode of CS/PDA(C)-GOx/Au in phosphate buffer solution containing 100 mM glucose and 4.0 mM BQ and a carbon cathode in Nafion-membrane-isolated acidic KMnO(4), and its maximum power density of 1.62 mW cm(-2) is superior to those of most BFC hitherto reported.     

Resting cells of recombinant E. coli show high epoxidation yields on energy source and high sensitivity to product inhibition

Metabolically active resting (i.e., nongrowing) bacterial cells have a high potential in cofactor-dependent redox biotransformations. Where growing cells require carbon and energy for biomass production, resting cells can potentially exploit their metabolism more efficiently for redox biocatalysis allowing higher specific activities and product yields on energy source. Here, the potential of resting recombinant E. coli containing the styrene monooxygenase StyAB was investigated for enantioselective styrene epoxidation in a two-liquid phase setup. Resting cells indeed showed twofold higher specific activities as compared to growing cells in a similar setup. However, product formation rates decreased steadily resulting in lower final product concentrations. The low intrinsic stability of the reductase component StyB was found to limit overall biocatalyst stability. Such limitation by enzyme stability was overcome by increasing intracellular StyB levels. Beyond that, product inhibition was identified as a limiting factor, whereas complete toxification of the bacterial cells, as it was observed with growing cells, and deactivation of the multicomponent enzyme system did not occur. The resting cell setup allowed high product yields on glucose of more than 5 mol mol(glucose)(-1), which makes the use of resting cells a promising approach for ecologically as well as economically sustainable oxygenase-based whole-cell biocatalysis.     

Adzuki bean: A new resource of biocatalyst for asymmetric reduction of aromatic ketones with high stereoselectivity and substrate tolerance

A new resource of biocatalyst for asymmetric reduction of aromatic ketones has been discovered for the first time from a common plant seed, adzuki bean, i.e. Phaseolus angularis (Willd.) W.F. Wight. The study investigated the best methods to prepare the biocatalyst and its ability to reduce ketones. Our results indicated that the biocatalyst from adzuki bean could reduce various aromatic ketones at relatively high concentrations (e.g. 100 mM), exhibiting excellent stereoselectivity (>98% e.e.). In addition, it was found that NADPH acts as the reducing cofactor, which can be regenerated by the crude enzyme system itself using glucose as an auxiliary substrate.     

The effects of low-speed swimming following exhaustive exercise on metabolic recovery and swimming performance in brook trout (Salvelinus fontinalis)

Experiments were conducted to determine whether low-speed swimming during recovery from exhaustive exercise improved both metabolic recovery and performance during a swimming challenge. For these experiments, brook trout were allowed to recover from exhaustive exercise for 2 h while swimming at 0, 0.5, 1.0, or 1.5 body length (BL) s(-1) or allowed to recover from exhaustive exercise for 1, 2, or 3 h while swimming at 1.0 BL s(-1). At the appropriate interval, either (i) muscle and blood samples were removed from the fish or (ii) fish were assessed for performance (i.e., fatigue time) during a fixed-interval swimming test. Low-speed swimming during recovery from exhaustive exercise resulted in significantly longer fatigue times compared with fish recovering in still water (i.e., 0 BL s(-1)). However, swimming during recovery did not expedite recovery of muscle lactate or blood variables (e.g., lactate, osmolarity, glucose). These observations suggest that metabolic recovery and subsequent swimming performance may not be directly linked and that other factors play a role in swimming recovery in brook trout.     

Response surface methodology-based optimization of glucose acylation bio-catalyzed by immobilized lipase

This paper describes in detail the selection and optimization of immobilized lipases for enhanced regioselective acylation of glucose into glucose monolaurate (GlcML). Initially, nature of biocatalyst, immobilization approach, reaction media, glucose, and lauric acid concentration were screened out. Finally, lipases from Rhizopus arrhizus immobilized on dead mycelia were investigated under various reaction conditions (Temperature, shaking speed, enzyme dose, and water content) following a fully rotatable central composite design (FRCCD) to optimize the activity of lipases. The immobilized lipases-based biocatalysts in the presence of polar solvents (tertiary alcohols) and higher concentrations of substrates i.e. glucose and lauric acid (100 and 300?mmol?L^?1, respectively) offered conversion rate of 1.5 mmolmin^?1?L^?1. Moreover, optimization of reaction conditions revealed that 162.5 lipase units/100mL at 31.25?°C, 3% water content, and 105?RPM shaking speed enhanced the conversion rate by 0.5 mmolmin^?1?L^?1 rendering the reaction more economical. Hence, lipases-based immobilized biocatalysts may provide an intelligent and green choice for commercial scale synthesis of GlcML for food and pharmaceutical industries.     

Hepatic autoregulation: response of glucose production and gluconeogenesis to increased glycogenolysis

The effect of increased glycogenolysis, simulated by galactose's conversion to glucose, on the contribution of gluconeogenesis (GNG) to hepatic glucose production (GP) was determined. The conversion of galactose to glucose is by the same pathway as glycogen's conversion to glucose, i.e., glucose 1-phosphate --> glucose 6-phosphate --> glucose. Healthy men (n = 7) were fasted for 44 h. At 40 h, hepatic glycogen stores were depleted. GNG then contributed approximately 90% to a GP of approximately 8 micromol.kg(-1).min(-1). Galactose, 9 g/h, was infused over the next 4 h. The contribution of GNG to GP declined from approximately 90% to 65%, i.e., by approximately 2 micromol.kg(-1).min(-1). The rate of galactose conversion to blood glucose, measured by labeling the infused galactose with [1-(2)H]galactose (n = 4), was also approximately 2 micromol.kg(-1).min(-1). The 41st h GP rose by approximately 1.5 micromol.kg(-1).min(-1) and then returned to approximately 9 micromol.kg(-1).min(-1), while plasma glucose concentration increased from approximately 4.5 to 5.3 mM, accompanied by a rise in plasma insulin concentration. Over 50% of the galactose infused was accounted for in blood glucose and hepatic glycogen formation. Thus an increase in the rate of GP via the glycogenolytic pathway resulted in a concomitant decrease in the rate of GP via GNG. While the compensatory response to the galactose administration was not complete, since GP increased, hepatic autoregulation is operative in healthy humans during prolonged fasting.     

两种发酵食品对糖尿病模型小鼠血糖及血脂的影响

目的：观察诺丽果汁和纳豆两种发酵食品对实验性糖尿病小鼠血糖及血脂的影响。方法：ICR雌性小鼠一次性尾静脉注射四氧嘧啶（55 mg/kg）,72 h后将空腹血糖值≥ 12.00 mmol/L、尿糖呈强阳性（+++）者视为糖尿病小鼠模型。将糖尿病模型小鼠随机分为3组（n=10）：模型（DM）组、诺丽果汁（NJ）组和纳豆（NT）组,另取10只正常ICR雌性小鼠作为正常对照（NC）组。NJ组、NT组分别给予诺丽果汁（25.0 ml/kg）、纳豆（0.6 g/kg）灌胃,其他两组小鼠分别给予生理盐水（25.0 ml/kg）灌胃,连续给药30 d,小鼠自由进食、饮水,记录小鼠饮水量及进食量。末次给药后1.5 h,测定小鼠葡萄糖耐量,经股动脉采血测定小鼠糖化血清蛋白（GSP）、血清胰岛素（Ins）和血脂等指标的变化情况。结果：与NC组比较,DM组小鼠饮水量、进食量、GSP及血清总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白（LDL）等均显著升高（P<0.01）,葡萄糖耐量、Ins及高密度脂蛋白（HDL）均显著降低（P<0.01）;与DM组比较,NJ组与NT组小鼠GSP、TG及LDL均明显降低（P<0.01,P<0.05）,葡萄糖耐量、Ins和HDL明显升高（P<0.05）。结论：诺丽果汁与纳豆具有降低糖尿病模型小鼠血糖、增加糖耐量及改善血脂的作用,提示二者对糖尿病防治可能具有一定的应用价值。     

Glucocorticoids Inhibit Glucose Transport and Glutamate Uptake in Hippocampal Astrocytes: Implications for Glucocorticoid Neurotoxicity

Glucocorticoids (GCs), the adrenal steroid hormones secreted during stress, can damage the hippocampus and impair its capacity to survive coincident neurological insults. This GC endangerment of the hippocampus is energetic in nature, as it can be prevented when neurons are supplemented with additional energy substrates. This energetic endangerment might arise from the ability of GCs to inhibit glucose transport into both hippocampal neurons and astrocytes. The present study explores the GC inhibition in astrocytes. (1) GCs inhibited glucose transport approximately 15-30% in both primary and secondary hippocampal astrocyte cultures. (2) The parameters of inhibition agreed with the mechanisms of GC inhibition of glucose transport in peripheral tissues: A minimum of 4 h of GC exposure were required, and the effect was steroid specific (i.e., it was not triggered by estrogen, progesterone, or testosterone) and tissue specific (i.e., it was not triggered by GCs in cerebellar or cortical cultures). (3) Similar GC treatment caused a decrease in astrocyte survival during hypoglycemia and a decrease in the affinity of glutamate uptake. This latter observation suggests that GCs might impair the ability of astrocytes to aid neurons during times of neurologic crisis (i.e., by impairing their ability to remove damaging glutamate from the synapse).     

Enzyme precipitate coatings of glucose oxidase onto carbon paper for biofuel cell applications

Enzymatic biofuel cells (BFC) have a great potential as a small power source, but their practical applications are being hampered by short lifetime and low power density. This study describes the direct immobilization of glucose oxidase (GOx) onto the carbon paper in the form of highly stable and active enzyme precipitation coatings (EPCs), which can improve the lifetime and power density of BFCs. EPCs were fabricated directly onto the carbon paper via a three-step process: covalent attachment (CA), enzyme precipitation, and chemical crosslinking. GOx-immobilized carbon papers via the CA and EPC approaches were used as an enzyme anode and their electrochemical activities were tested under the BFC-operating mode. The BFCs with CA and EPC enzyme anodes produced the maximum power densities of 50 and 250 μW/cm(2) , respectively. The BFC with the EPC enzyme anode showed a stable current density output of >700 μA/cm(2) at 0.18 V under continuous operation for over 45 h. When a maple syrup was used as a fuel under ambient conditions, it also produced a stable current density of >10 μA/cm(2) at 0.18 V for over 25 h. It is anticipated that the direct immobilization of EPC on hierarchical-structured electrodes with a large surface area would further improve the power density of BFCs that can make their applications more feasible.     

Accelerated biocatalyst stability testing for process optimization

The deactivation of protein biocatalysts even at relatively low temperatures is one of the principal drawbacks to their use. To aid in the development of novel biocatalysts, we have derived an equation for both time- and temperature-dependent activity of the biocatalyst based on known concepts such as transition state theory and the Lumry-Eyring model. We then derived an analytical solution for the total turnover number (ttn), under isothermal operation, as a function of the catalytic constant kcat, the unfolding equilibrium constant K, and the intrinsic first-order deactivation rate constant(s) k(d,i). Employing an immobilized glucose isomerase biocatalyst in a CSTR and utilizing a linear temperature ramp beyond the Tm of the enzyme, we demonstrate an accelerated method for extracting the thermodynamic and kinetic constants describing the biocatalyst system. In addition, we demonstrate that the predicted biocatalyst behavior at different temperatures and reaction times is consistent with the experimental observations.     

Novel biotransformation process of podophyllotoxin to produce podophyllic acid and picropodophyllotoxin by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> CCTCC AB93066. Part I: Process development

A novel biotransformation process of podophyllotoxin (1) to produce picropodophyllotoxin (2) and podophyllic acid (3) was developed in this work. Eight bacteria which could modify the structure of podophyllotoxin were screened out from the tested fourteen bacteria. The highest conversion of podophyllotoxin (i.e., 70.2 ± 8.0%) was obtained when Pseudomonas aeruginosa CCTCC AB93066 was used as biocatalyst, so P. aeruginosa was selected as a typical biocatalyst in the following study. Product (2) and (3) were separated through D312 macroporous resin and sephadex LH-20 gel column chromatograph. On the basis of ¹H NMR, ¹³C NMR, ESI–MS and Elemental Analysis, product (2) and (3) were identified as picropodophyllotoxin (2) and podophyllic acid (3), respectively. This suggested the site-specific isomerization and hydrolization of podophyllotoxin occurred during its biotransformation process by P. aeruginosa. For the first time, podophyllotoxin was biotransformed into its hydrolytic derivate (i.e., podophyllic acid).     

Plant lipases: biocatalyst aqueous environment in relation to optimal catalytic activity in lipase-catalyzed synthesis reactions.

Adsorption and desorption isotherms of two commercial enzyme preparations of papain and bromelain were determined with a Dynamic Vapor System. The Guggenheim-Anderson-deBoer (GAB) modeling of the obtained sorption isotherms allowed the definition of different levels of hydration of those samples. Afterward, these enzyme preparations were used as biocatalysts in water and solvent-free esterification and alcoholysis reactions. The evolution of the obtained fatty acid ester level as a function of the initial hydration level of the biocatalyst, i.e., thermodynamic water activity (a(w)) and water content, was studied. The results show an important correlation between the initial hydration level of the biocatalyst and its catalytic activity during the lipase-catalyzed synthesis reactions. Thus, the Carica papaya lipase (crude papain preparation) catalytic activity is highly dependent on the biocatalyst hydration state. The optimized synthesis reaction yield is obtained when the a(w) value of the enzyme preparation is stabilized at 0.22, which corresponds to 2% water content. This optimal level of hydration occurs on the linear part of the biocatalyst's sorption isotherm, where the water molecules can form a mono- or multiple layer with the protein network. The synthesis reaction yield decreases when the a(w) of the preparation is higher than 0.22, because the excess water molecules modify the system equilibrium leading to the reverse and competitive reaction, i.e., hydrolysis. These results show also that an optimal storage condition for the highly hydrophilic crude papain preparation is a relative humidity strictly lower than 70% to avoid an irreversible structural transition leading to a useless biocatalyst. Concerning the bromelain preparation, no effect of the hydration level on the catalytic activity during esterification reactions was observed. This biocatalyst has too weak a catalytic activity which makes it difficult to observe any differences. Furthermore, the bromelain preparation is far more hydrophobic as it adsorbs only 18 g of water per 100 g of dry material at a(w) around 0.90. No deliquescence of this enzymatic preparation is observed at this a(w) value.     

Clarified cashew apple juice as alternative raw material for biosurfactant production by Bacillus subtilis in a batch bioreactor

Clarified cashew apple juice was evaluated as carbon source for surfactin production by Bacillus subtilis LAMI005 isolated from the tank of chlorination at the Wastewater Treatment Plant on Campus do Pici (WWTP-PICI) in the Federal University of Ceará, Brazil. The highest surfactin concentration using clarified cashew apple juice (CCAJ) supplemented with mineral medium (MM-CCAJ) was 123 mg/L, achieved after 48 h of fermentation. Almost 2-fold less than the amount produced using mineral medium supplemented with 10 g/L of glucose and 8.7 g/L of fructose (MM-GF). However, critical micelle concentration of the biosurfactants produced using MM-CCAJ was 2.5-fold lower than the one produced using MM-GF, which indicates it is a more efficient biosurfactant. Surface tension decreased from 38.50 ± 0.0 to 29.00 ± 0.0 dyne/cm when B. subtilis was grown on MM-CCAJ media (24.68% of reduction on surface tension) and remained constant up to 72 h. Emulsification index was 51.15 and 66.70% using soybean oil and kerosene, respectively. Surfactin produced in MM-CCAJ showed an emulsifying activity of, respectively, 1.75 and 2.3 U when n-hexadecane or soybean oil was tested. However, when mineral medium supplemented with 10 g/L of glucose (MM-G) was used an emulsifying activity of 2.0 and 1.75 U, with n-hexadecane and soybean oil, respectively, was obtained. These results indicate that it is feasible to produce surfactin from CCAJ, a renewable and low-cost carbon source.     

Visible light-induced photooxidation of glucose sensitized by riboflavin

We conducted this study to evaluate the oxidation of glucose induced by visible light in the presence of sensitizers such as methylene blue and flavins (i.e., flavin mononucleotide and riboflavin). The concentration of the sensitizers was similar to that of flavin in parenteral nutrients. The photooxidation of glucose sensitized by flavin mononucleotide or riboflavin was greater than that which was observed in the presence of methylene blue, whereas the isotopic effect of deuterium oxide (D(2)O) was enhanced more substantially in the presence of methylene blue than in the presence of flavins. These results show that methylene blue exerts its action through singlet oxygen and that at a high substrate concentration (as was used in this work) flavin mononucleotide and riboflavin act preferentially as type I sensitizers. In the flavin photosensitized processes, the presence of hydrogen peroxide, superoxide anion, and hydroxyl radical was demonstrated. The photooxidation of glucose is favored by an increase in pH, and it also depends on the energy absorbed by the system. By using a specific reagent for glucose (i.e., o-toluidine), it was possible to quantify the photoconversion of glucose. The results obtained in this work should be considered in the management of glucose-containing parenteral nutrients that are exposed to visible light in the presence of a multivitamin complex containing flavin mononucleotide.     

Carbon and energy balances in cell-recycle cultures of Schizosaccharomyces pombe

A strain of the fission yeast Schizosaccharomyces pombe was aerobically grown in a cell-recycle fermentor under various operating conditions, i.e., different bleeding rates and various separate feed rates of glucose and basal medium. Carbon and energy balances were analyzed during steady-state culture regimes, allowing growth yields and maintenance coefficients to be determined under glucose-limited and glucose-excess environments. Special attention was given to the metabolic shift from purely oxidative to respirofermentative glucose catabolism resulting from a change in the growth-limiting factor. No maintenance requirements for the carbon source and for energy were observed during glucose-limited culture regimes and oxidative catabolism. Under glucose excess and respirofermentative metabolism, the m(G) coefficient was shown to be growth-linked, whereas the enhancement of the apparent m(e) coefficient observed for increased residual glucose concentrations could be assigned to a decline in the ATP yield. (c) 1993 John Wiley & Sons, Inc.     

Integrated organic–aqueous biocatalysis and product recovery for quinaldine hydroxylation catalyzed by living recombinant Pseudomonas putida

In an earlier study, biocatalytic carbon oxyfunctionalization with water serving as oxygen donor, e.g., the bioconversion of quinaldine to 4-hydroxyquinaldine, was successfully achieved using resting cells of recombinant Pseudomonas putida, containing the molybdenum-enzyme quinaldine 4-oxidase, in a two-liquid phase (2LP) system (ütkür et al. J Ind Microbiol Biotechnol 38:1067-1077, 2011). In the study reported here, key parameters determining process performance were investigated and an efficient and easy method for product recovery was established. The performance of the whole-cell biocatalyst was shown not to be limited by the availability of the inducer benzoate (also serving as growth substrate) during the growth of recombinant P. putida cells. Furthermore, catalyst performance during 2LP biotransformations was not limited by the availability of glucose, the energy source to maintain metabolic activity in resting cells, and molecular oxygen, a possible final electron acceptor during quinaldine oxidation. The product and the organic solvent (1-dodecanol) were identified as the most critical factors affecting biocatalyst performance, to a large extent on the enzyme level (inhibition), whereas substrate effects were negligible. However, none of the 13 alternative solvents tested surpassed 1-dodecanol in terms of toxicity, substrate/product solubility, and partitioning. The use of supercritical carbon dioxide for phase separation and an easy and efficient liquid-liquid extraction step enabled 4-hydroxyquinaldine to be isolated at a purity of >99.9% with recoveries of 57 and 84%, respectively. This study constitutes the first proof of concept on an integrated process for the oxyfunctionalization of toxic substrates with a water-incorporating hydroxylase.     

Metabolic design for selective production of nicotinamide mononucleotide from glucose and nicotinamide

β-Nicotinamide mononucleotide (NMN) is, one of the nucleotide compounds, a precursor of NAD⁺ and has recently attracted attention as a nutraceutical. Here, we develop a whole-cell biocatalyst using Escherichia coli, which enabled selective and effective high production of NMN from the inexpensive feedstock substrates glucose and nicotinamide (Nam). Notably, we identify two actively functional transporters (NiaP and PnuC) and a high-activity key enzyme (Nampt), permitting intracellular Nam uptake, efficient conversion of phosphoribosyl pyrophosphate (PRPP; supplied from glucose) and Nam to NMN, and NMN excretion extracellularly. Further, enhancement of the PRPP biosynthetic pathway and optimization of individual gene expression enable drastically higher NMN production than reported thus far. The strain extracellularly produces 6.79 g l⁻¹ of NMN from glucose and Nam, and the reaction selectivity from Nam to NMN is 86%. Our approach will be promising for low-cost, high-quality industrial production of NMN and other nucleotide compounds using microorganisms.