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A novel hybrid material consisted of carbon covered Fe3O4 nanoparticles and MoS2 nanoflower (FCM) was designed and prepared by micelle-assisted hydrothermal methods. Multiple techniques, including X-Ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize it. The results show that FCM has a flower-like morphology with a 330 nm Fe3O4 core as well as 70 nm highly crystalline MoS2 shell. FCM is superparamagnetic with a saturation magnetization of 35 emu g−1. Then hydrocracking of Canadian bitumen residue (CBR) was applied to estimate its catalytic activity. The results show that FCM exhibits superior catalytic hydrocracking activity compared to bulk MoS2 and commercial oil-dispersed Mo(CO)6 by the same Mo loading. Further measurement by elemental analysis, XPS and XRD reveals that the MoS2 nanoflower with abundant catalytic active sites and covered carbon layer with anti-coke ability donate to the superior upgrading performance. Besides, the catalysts can be easily recovered by the external magnetic field. This work provides a novel kind magnetic nanocatalyst which is potential for slurry-phase hydrocracking applications.

We study the probability of an undetected error for general q-ary codes. We give upper and lower bounds on this quantity, by the Linear Programming and the Polynomial methods, as a function of the length, size, and minimum distance. Sharper bounds are obtained in the important special case of binary Hamming codes. Finally, several examples are given to illustrate the results of this paper.

The high production cost and poor electrochemical performance of polyanionic cathode hinders their industrial application. Here, the authors report large-scale fabrication of sodium vanadium fluorophosphates and in situ construction of their carbon nanocomposites via a mechanochemical protocol.

Acid saccharification of hemicelluloses offers promising pathways to sustainably diversify the revenue of the lignocellulose biorefinery industry. Electrodialysis to separate inorganic acids from acid hydrolysate in the hemicellulose saccharification process could realize the recovery of sulfuric acid, and significantly reduced the chemical consumption than the traditional ion exchange resins method. In this work, the deacidification of corncob acid hydrolysate was conducted by a homemade electrodialysis apparatus. The results showed that: (1) more than 99% of acid can be removed through the electrodialysis process; (2) A non-negligible membrane fouling occurred during the electrodialysis process, which aggravated with the repeated batch running The final global system resistance rose from 15.8 Ω (1st batch) to 43.9 Ω (10th batch), and the treatment ending time was delayed from 120 min (1st batch) to 162 min (10th batch); (4) About 90% of protein, 70% of ferulate acid, and 80% of p-coumarate acid precipitated from the corncob acid hydrolysate during the electrodialysis process. The zeta potential of corncob acid hydrolysate changed from a positive value to a negative value, and an isoelectric point around pH 2.3 was reached. HSQC, FTTR, and GPC, along with SEM and EDS analysis, revealed that the fouling layers mostly consisted of hydrolysates of protein and lignin. The result of HSQC indicated that the membrane foulant may exist in the form of lignin–carbohydrate complexes, as the lignin component of the membrane foulant is in the form of p-coumarate and ferulate. From the result of FTIR, a strong chemical bonding, such as a covalent linkage, existed between the lignin and protein in the membrane foulant. Throughout the electrodialysis process, the increased pH decreased the stability of colloidal particles, including lignin and proteins. Destabilized colloidal particles started to self-aggregate and form deposits on the anion exchange membrane’s surface. Over time, these deposits covered the entire membrane surface and the spaces between the membranes. Eventually, they attached to the surface of the cation exchange membrane. In the end, a suggestion to control and minimize membrane fouling in this process was discussed: lower pH as a process endpoint and a post-treatment method.

Abstract Background The fuel ethanol industry has made tremendous progress in the last decades. Ethanol can be obtained by fermentation using a variety of biomass materials as the feedstocks. However, few studies have been conducted on ethanol utilization by microorganisms. The price of petroleum-derived ethanol, easily made by the hydrolysis of ethylene, is even lower than that of bioethanol. If ethanol can be metabolized by microorganisms to produce value-added chemicals, it will open a new door for the utilization of inexpensive ethanol resources. Results We constructed an engineered Escherichia coli strain which could utilize ethanol as the sole carbon source. The alcohol dehydrogenase and aldehyde dehydrogenase from Aspergillus nidulans was introduced into E. coli and the recombinant strain acquired the ability to grow on ethanol. Cell growth continued when ethanol was supplied after glucose starvation and 2.24 g L−1 of ethanol was further consumed during the shake-flasks fermentation process. Then ethanol was further used for the production of mevalonic acid by heterologously expressing its biosynthetic pathway. Deuterium-labeled ethanol-D6 as the feedstock confirmed that mevalonic acid was synthesized from ethanol. Conclusions This study demonstrated the possibility of using ethanol as the carbon source by engineered E. coli strains. It can serve as the basis for the construction of more robust strains in the future though the catabolic capacity of ethanol should be further improved.

Abstract Microbial fuel cell (MFC) is an environmentally friendly technology for electricity harvesting from a variety of substrates. Microorganisms used as catalysts in the anodic chamber, which are termed as electricigens, play a major role in the operation of MFCs. This review provides an introduction to the currently identified electricigens on their taxonomical groups and electricity producing abilities. The mechanism of electron transfer from electricigens to electrode is highlighted. The performances of pure culture and mixed communities are compared particularly. It has been proved that the electricity generation capacity and the ability to adapt to the complex environment of MFC systems constructed by pure microbial cultures are less than the systems constructed by miscellaneous consortia. However, pure cultures are useful to clarify the electron transfer mechanism at the microbiological level and further reduce the complexity of mixed communities. Future research trends of electricigens in MFCs should be focused on screening, domestication, modification and optimization of multi-strains to improve their electrochemical activities. Although the MFC techniques have been greatly advanced during the past few years, the present state of this technology still requires to be combined with other processes for cost reduction.

Abstract Background Lycopene is a terpenoid pigment that has diverse applications in the food and medicine industries. A prospective approach for lycopene production is by metabolic engineering in microbial hosts, such as Escherichia coli. Isopentenyl diphosphate isomerase (IDI, E.C. 5.3.3.2) is one of the rate-limiting enzymes in the lycopene biosynthetic pathway and one major target during metabolic engineering. The properties of IDIs differ depending on the sources, but under physiological conditions, IDIs are limited by low enzyme activity, short half-life and weak substrate affinity. Therefore, it is important to prepare an excellent IDI by protein engineering. Results Directed evolution strategy (error-prone PCR) was utilized to optimize the activity of Saccharomyces cerevisiae IDI. Using three rounds of error-prone PCR; screening the development of a lycopene-dependent color reaction; and combinatorial site-specific saturation mutagenesis, three activity-enhancing mutations were identified: L141H, Y195F, and W256C. L141H, located near the active pocket inside the tertiary structure of IDI, formed a hydrogen bond with nearby β-phosphates of isopentenylpyrophosphate (IPP). Phe-195 and Cys-256 were nonpolar amino acids and located near the hydrophobic group of IPP, enlarging the hydrophobic scope, and the active pocket indirectly. Purified IDI was characterized and the result showed that the K m of mutant IDI decreased by 10% compared with K m of the parent IDI, and K cat was 28% fold improved compared to that of the original IDI. Results of a fermentation experiment revealed that mutant IDI had a 1.8-fold increased lycopene production and a 2.1-fold increased yield capacity compared to wild-type IDI. Conclusion We prepared an engineered variant of IDI with improved catalytic activity by combining random and site directed mutagenesis. The best mutants produced by this approach enhanced catalytic activity while also displaying improved stability in pH, enhanced thermostability and longer half-life. Importantly, the mutant IDI could play an important role in fed-batch fermentation, being an effective and attractive biocatalyst for the production of biochemicals.

Abstract Background Phloroglucinol is an important chemical which has been successfully produced by engineered Escherichia coli. However, the toxicity of phloroglucinol can enormously inhibit E. coli cell growth and viability, and the productivity is still too low and not economically feasible for industrial applications. Therefore, strain tolerance to toxic metabolites remains a key issue during the production of chemicals using biological processes. Results In the present work, we examined the impact of the native GroESL chaperone system with different overexpression levels on phloroglucinol tolerance and production in E. coli. The groESL gene was cloned into an expression vector, of which expression level was regulated by three different promoters (natural, tac and T7 promoter). Strain tolerance was evaluated employing viable cell counts and phloroglucinol production. In comparison with the control strain, all GroESL overexpressing strains showed good characteristics in cell viability and phloroglucinol synthesis. Strain which overexpressed GroESL under tac promoter was found to show the best tolerance in all of those tested, resulting in a 3.19-fold increase in viable cell numbers compared with control strain of agar-plate culture under the condition of 0.7 g/L phloroglucinol, and a 39.5% increase in phloroglucinol production under fed-batch fermentation. This engineered strain finally accumulated phloroglucinol up to 5.3 g/L in the fed-batch cultivation 10 h after induction, and the productivity was 0.53 g/L/h. To date, the highest phloroglucinol production was achieved in this work compared with the previous reports, which is promising to make the bioprocess feasible from the economical point. Conclusions The data show that appropriate expression level of GroESL plays a critical role in improving phloroglucinol tolerance and production in E. coli, and maybe involve in controlling some aspects of the stress response system through upregulation of GroESL. GroESL overexpression is therefore a feasible and efficient approach for improvement of E. coli tolerance.

Abstract Background d-Lactate is a valued chemical which can be produced by some bacteria including Klebsiella pneumoniae. However, only a few studies have focused on K. pneumoniae for d-lactate production with a significant amount of by-products, which complicated the purification process and decreased the yield of d-lactate. Results Based on the redirection of carbon towards by-product formation, the effects of single-gene and multiple-gene deletions in K. pneumoniae on d-lactate production from glucose via acetolactate synthase (budB), acetate kinase (ackA), and alcohol dehydrogenase (adhE) were tested. Klebsiella pneumoniae mutants had different production behaviours. The accumulation of the main by-products was decreased in the mutants. The triple mutant strain had the most powerful ability to produce optically pure d-lactate from glucose, and was tested with xylose and arabinose as carbon sources. Fed-batch fermentation was also carried out under various aeration rates, and the strain accumulated 125.1 g/L d-lactate with a yield of 0.91 g/g glucose at 2.5 vvm. Conclusions Knocking out by-product synthesis genes had a remarkable influence on the production and yield of d-lactate. This study demonstrated, for the first time, that K. pneumoniae has great potential to convert monosaccharides into d-lactate. The results provide new insights for industrial production of d-lactate by K. pneumoniae.

Abstract Background Phloroglucinol is an important chemical, and the biosynthesis processes which can convert glucose to phloroglucinol have been established. However, due to approximate 80% of the glucose being transformed into undesirable by-products and biomass, this biosynthesis process only shows a low yield with the highest value of about 0.20 g/g. The industrial applications are usually hindered by the low current productivity and yield and also by the high costs. Generally, several different aspects limit the development of phloroglucinol biosynthesis. The yield of phloroglucinol is one of the most important parameters for its bioconversion especially from economic and ecological points of view. The in vitro biosynthesis of bio-based chemicals, is a flexible alternative with potentially high-yield to in vivo biosynthetic technology. Results By comparing the activity of acetyl-CoA synthetase (ACS) from Escherichia coli and Acetobacter pasteurianus, the highly active ACS2 was identified in A. pasteurianus. Acetyl-CoA carboxylase (ACC) from Acinetobacter calcoaceticus and phloroglucinol synthase (PhlD) from Pseudomonas fluorescens pf-5 were expressed and purified. Acetate was successfully transformed into phloroglucinol by the combined activity of above-mentioned enzymes and required cofactor. After optimization of the in vitro reaction system, phloroglucinol was then produced with a yield of nearly 0.64 g phloroglucinol/g acetic acid, which was equal to 91.43% of the theoretically possible maximum. Conclusions In this work, a novel in vitro synthetic system for a highly efficient production of phloroglucinol from acetate was demonstrated. The system’s performance suggests that in vitro synthesis of phloroglucinol has some advantages and is potential to become a feasible industrial alternative. Based on the results presented herewith, it is believed that in vitro biosystem will provide a feasible option for production of important industrial chemicals from acetate, which could work as a versatile biosynthetic platform.

The authors of this article [1] wish to draw the readers’ attention to their closely related paper, published in RSC Advances [2] which should have been cited in this article. The authors regret that there is unattributed overlap in text describing the construction of the plasmid coding for the biosynthetic pathway because of the commonly used research strategies between this article [1] and similar work presented in RSC Advances, although this does not affect the main scientific conclusion in this study.

Poly(3-hydroxypropionate) (P3HP) is a thermoplastic with great compostability and biocompatibility, and can be produced through several biosynthetic pathways, in which the glycerol pathway achieved the highest P3HP production. However, exogenous supply of vitamin B12 was required to maintain the activity of glycerol dehydratase, resulting in high production cost. To avoid the addition of VB12, we have previously constructed a P3HP biosynthetic route with β-alanine as intermediate, and the present study aimed to improve the P3HP production of this pathway. L-aspartate decarboxylase PanD was found to be the rate-limiting enzyme in the β-alanine pathway firstly. To improve the pathway efficiency, PanD was screened from four different sources (Escherichia coli, Bacillus subtilis, Pseudomonas fluorescens, and Corynebacterium glutamicum). And PanD from C. glutamicum was found to have the highest activity, the P3HP production was improved in flask cultivation with this enzyme. To further improve the production, the host strain was screened and the culture condition was optimized. Under optimal conditions, production and content of P3HP reached to 10.2 g/L and 39.1% (wt/wt [cell dry weight]) in an aerobic fed-batch fermentation. To date, this is the highest P3HP production without VB12.

With the methodical advancement of the Energy Internet Marketing Service System across each network province in accordance with the blueprint, the company's marketing business development has ushered into the digital era, thereby necessitating elevated benchmarks for the system's security, reliability, cost-effectiveness, agility, and operational efficiency. Through an exhaustive scrutiny encompassing marketing business dynamics, technical architecture intricacies, and system operational modalities, the imperative arises for the replacement of the Oracle database and the advocacy for a feasibility study exploring the migration to a localized database system. Within this framework, the grid marketing service system's domestic database migration project confronts myriad challenges and risks. To ensure the seamless implementation of the project, this paper embarks from the vantage point of the project's specific context, amalgamating well-established risk management paradigms and methodologies. Leveraging the trapezoidal fuzzy number and material element topology computational model, potential risk factors are methodically discerned. Subsequently, the project's overall risk landscape is meticulously charted through the lens of this model, culminating in the formulation of targeted risk response strategies and a comprehensive feasibility assessment predicated upon the weighted ranking of risk factors. Ultimately, an array of corresponding risk response measures are delineated, spanning organizational, managerial, scheduling, and technical domains, thereby ensuring the seamless, steadfast, and efficacious implementation of the project, poised to furnish resolute support for its sustained operation post-migration. The research findings of this paper not only provide robust assurance for the feasibility of the migration project concerning the homegrown database system of the grid marketing service system but also offer invaluable theoretical insights and pragmatic wisdom poised to enrich the execution of analogous endeavors. [ABSTRACT FROM AUTHOR]

A study employs the Fourier transform infrared and the NMR spectroscopy to analyze the effects of the ionic liquids on the aggregation behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers in the aqueous solution. The research has proved to be extremely helpful in studying such effects and shows that at low concentration of the BmimBr, miscelles are formed in the aqueous solution.

Transmission electron microscopy (TEM), particle size analyzer (PSA), Fourier transformed infrared and fluorescence spectroscopy are used to investigate the acid effect on the aggregation of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers E[O.sub.20]P[O.sub.70]E[O.sub.20]. It is attributed to the aggregation of micelles through the protonated water bridges between different micelles through hydrogen bonds.

The vgb gene, encoding Vitreoscilla hemoglobin (VHb), is introduced into a specific desulfurization bacterium, Rhodococcus erythropolis LSSE8-1, where the VHb-specific spectrum is seen for the recombinant. It is shown that the strain bearing vgb displayed a higher biomass yield and desulfurizing activity when compared to the wild type.

Microbial cells of Pseudomonas delafieldii were coated with magnetic nanoparticles and then immobilized by external application of a magnetic field. The results showed that the cells coated with Fe(sub 3)O(sub 4) nanoparticles had greater desulfurizing activity and operational stability

Background: Acetyl-CoA-derived chemicals are suitable for multiple applications in many industries. The bio-production of these chemicals has become imperative owing to the economic and environmental problems. However, acetate overflow is the major drawback for acetyl-CoA-derived chemicals production. Approaches for overcoming acetate overflow may be beneficial for the production of acetyl-CoA-derived chemicals. Results: In this study, a transcriptional regulator iclR was knocked out in E.coli BL21(DE3) to overcome acetate overflow and improve the chemicals production. Two important acetyl-CoA-derived chemicals, phloroglucinol (PG) and 3-hydroxypropionate (3HP) were used to evaluate it. It is revealed that knockout of iclR significantly increased expressions of aceBAK operon. The cell yields and glucose utilization efficiencies were higher than those of control strains. The acetate concentrations were decreased by more than 50% and the productions of PG and 3HP were increased more than twice in iclR mutants. The effects of iclR knockout on cell physiology, cell metabolism and production of acetyl-CoA-derived chemicals were similar to those of arcA knockout in our previous study. However, the arcA-iclR double mutants couldn't gain higher productions of PG and 3HP. The mechanisms are unclear and needed to be resolved in future. Conclusions: Knockout of iclR significantly increased gene expression of aceBAK operon and concomitantly activated glyoxylate pathway. This genetic modification may be a good way to overcome acetate overflow, and improve the production of a wide range of acetyl-CoA-derived chemicals. [ABSTRACT FROM AUTHOR]

Background: Diols are important monomers for the production of plastics and polyurethanes, which are widely used in our daily life. The medium-chain diols with one hydroxyl group at its subterminal end are able to confer more flexibility upon the synthesized materials. But unfortunately, this type of diols has not been synthesized so far. The strong need for advanced materials impelled us to develop a new strategy for the production of these novel diols. In this study, we use the remodeled P450BM3 for high-specificity production of 1,7-decanediol. Results: The native P450BM3 was capable of converting medium-chain alcohols into corresponding α, ω1-, α, ω2- and α, ω3-diols, with each of them accounting for about one third of the total diols, but it exhibited a little or no activity on the short-chain alcohols. Greatly improved regiospecificity of alcohol hydroxylation was obtained by laboratory evolution of P450BM3. After substitution of 12 amino acid residues (J2-F87A), the ratio of 1,7-decanediol (ω-3 hydroxylation) to total decanediols increased to 86.8 % from 34.0 %. Structure modeling and site-directed mutagenesis demonstrated that the heme end residues such as Ala78, Phe87 and Arg255 play a key role in controlling the regioselectivity of the alcohol hydroxylation, while the residues at the mouth of substrate binding site is not responsible for the regioselectivity. Conclusions: Herein we employ an engineered P450BM3 for the first time to enable the high-specificity biosynthesis of 1,7-decanediol, which is a promising monomer for the development of advanced materials. Several key amino acid residues that control the regioselectivity of alcohol hydroxylation were identified, providing some new insights into how to improve the regiospecificity of alcohol hydroxylation. This report not only provides a good strategy for the biosynthesis of 1,7-decanediol, but also gives a promising approach for the production of other useful diols. [ABSTRACT FROM AUTHOR]

Background: Geraniol is an acyclic monoterpene alcohol, which exhibits good prospect as a gasoline alternative. Geraniol is naturally encountered in plants at low concentrations and an attractive target for microbial engineering. Geraniol has been heterologously produced in Escherichia coli, but the low titer hinders its industrial applications. Moreover, bioconversion of geraniol by E. coli remains largely unknown. Results: Recombinant overexpression of Ocimum basilicum geraniol synthase, Abies grandis geranyl diphosphate synthase, and a heterotic mevalonate pathway in E. coli BL21 (DE3) enabled the production of up to 68.6 ± 3 mg/L geraniol in shake flasks. Initial fed-batch fermentation only increased geraniol production to 78.8 mg/L. To further improve the production yield, the fermentation conditions were optimized. Firstly, 81.4% of volatile geraniol was lost during the first 5 h of fermentation in a solvent-free system. Hence, isopropyl myristate was added to the culture medium to form an aqueous-organic two-phase culture system, which effectively prevented volatilization of geraniol. Secondly, most of geraniol was eventually biotransformed into geranyl acetate by E. coli, thus decreasing geraniol production. For the first time, we revealed the role of acetylesterase (Aes, EC 3.1.1.6) from E. coli in hydrolyzing geranyl acetate to geraniol, and production of geraniol was successfully increased to 2.0 g/L under controlled fermentation conditions. Conclusions: An efficient geraniol production platform was established by overexpressing several key pathway proteins in engineered E. coli strain combined with a controlled fermentation system. About 2.0 g/L geraniol was obtained using our controllable aqueous-organic two-phase fermentation system, which is the highest yield to date. In addition, the interconversion between geraniol and geranyl acetate by E. coli was first elucidated. This study provided a new and promising strategy for geraniol biosynthesis, which laid a basis for large-scale industrial application. [ABSTRACT FROM AUTHOR]

Background: Hydroxy fatty acids (HFAs) are valuable chemicals for a broad variety of applications. However, commercial production of HFAs has not been established so far due to the lack of low cost routes for their synthesis. Although the microbial transformation pathway of HFAs was extensively studied decades ago, these attempts mainly focused on converting fatty acids or vegetable oils to their hydroxyl counterparts. The use of a wider range of feedstocks to produce HFAs would reduce the dependence on oil crops and be expected to cut down the manufacturing cost. Results: In this study, the industrially important microorganism Escherichia coli was engineered to produce HFAs directly from glucose. Through the coexpression of the acetyl-CoA carboxylase (ACCase) and the leadless acyl-CoA thioesterase ('TesA), and knockout of the endogenous acyl-CoA synthetase (FadD), an engineered E. coli strain was constructed to efficiently synthesize free fatty acids (FFAs). Under shake-flask conditions, 244.8 mg/L of FFAs were obtained by a 12 h induced culture. Then the fatty acid hydroxylase (CYP102A1) from Bacillus megaterium was introduced into this strain and high-level production of HFAs was achieved. The finally engineered strain BL21ΔfadD/ pE-A1'tesA&pA-acc accumulated up to 58.7 mg/L of HFAs in the culture broth. About 24 % of the FFAs generated by the thioesterase were converted to HFAs. Fatty acid composition analysis showed that the HFAs mainly consisted of 9-hydroxydecanoic acid (9-OH-C10), 11-hydroxydodecanoic acid (11-OH-C12), 10-hydroxyhexadecanoic acid (10-OHC16) and 12-hydroxyoctadecanoic acid (12-OH-C18). Fed-batch fermentation of this strain further increased the final titer of HFAs to 548 mg/L. Conclusions: A robust HFA-producing strain was successfully constructed using glucose as the feedstock, which demonstrated a novel strategy for bioproduction of HFAs. The results of this work suggest that metabolically engineered E. coli has the potential to be a microbial cell factory for large-scale production of HFAs. [ABSTRACT FROM AUTHOR]

Background: To deal with the increasingly severe energy crisis and environmental consequences, biofuels and biochemicals generated from renewable resources could serve as a promising alternative for replacing petroleum as a source of fuel and chemicals, among which isoprene (2-methyl-1,3-butadiene) in particular is of great significance in that it is an important platform chemical, which has been used in industrial production of synthetic rubber for tires and coatings or aviation fuel. Results: We firstly introduced fatty acid decarboxylase (OleTJE) from Jeotgalicoccus species into E. coli to directly convert MVA(mevalonate) into 3-methy-3-buten-1-ol. And then to transform 3-methy-3-buten-1-ol to isoprene, oleate hydratase (OhyAEM) from Elizabethkingia meningoseptica was overexpressed in E. coli. A novel biosynthetic pathway of isoprene in E. coli was established by co-expressing the heterologous mvaE gene encoding acetyl-CoA acetyltransferase/HMG-CoA reductase and mvaS gene encoding HMG-CoA synthase from Enterococcus faecalis, fatty acid decarboxylase (OleTJE) and oleate hydratase (OhyAEM). Furthermore, to enhance isoprene production, a further optimization of expression level of OleTJE, OhyAEM was carried out by using different promoters and copy numbers of plasmids. Thereafter, the fermentation process was also optimized to improve the production of isoprene. The final engineered strain, YJM33, bearing the innovative biosynthetic pathway of isoprene, was found to produce isoprene up to 2.2 mg/L and 620 mg/L under flask and fed-batch fermentation conditions, respectively. Conclusions: In this study, by using metabolic engineering techniques, the novel MVA-mediated biosynthetic pathway of isoprene was successfully assembled in E. coli BL21(DE3) with the heterologous MVA upper pathway, OleTJE from Jeotgalicoccus species and OhyAEM from Elizabethkingia meningoseptica. Compared with traditional MVA pathway, the novel pathway is shortened by 3 steps. In addition, this is the first report on the reaction of converting MVA into 3-methy-3-buten-1-ol by fatty acid decarboxylase (OleTJE) from Jeotgalicoccus species. In brief, this study provided an alternative method for isoprene biosynthesis, which is largely different from the well-developed MEP pathway or MVA pathway. [ABSTRACT FROM AUTHOR]

In this work, we have reported a unique strategy of using Meta-Chloroperoxybenzoic acid (m-CPBA) as an oxidant for Polyaniline (PANI) nanofibers preparation. A templateless rapid mixing method was employed for chemical polymerization of aniline at room temperature under rapid mixing and without use of additional oxidant. PANI nanofibers were fully characterized and their electrochemical properties have been studied in detail. Further, effects of toluene solution on PANI electrochemical properties were also investigated in detail. The results showed that PANI nanofibers, in the presence of toluene as solvent, had relatively high specific capacitance and high columbic efficiency compared to their bulk solution, which was due to the immobile of toluene solution and the fast diffusion of the H ions through the polymer material during the redox process. [ABSTRACT FROM AUTHOR]