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Nylon 54 is a novel, biodegradable polyamide with excellent thermal resistance and water absorption properties. It can be polymerized using bio-based cadaverine and succinic acid as monomers. Traditional separation methods isolate individual monomers from the fermentation broth through acidification or alkalization, resulting in significant amounts of waste salts; however, synchronous separation of dibasic acids and diamines has not been reported. This study investigated an integrated process for the separation and extraction of nylon 54 salts from a co-fermentation broth without acidification or alkalization. We meticulously optimized the operational parameters of the integrated process to achieve maximum separation efficiency. Following microfiltration, ultrafiltration, and decolorization, the bacterial eliminating rate was ≥99.83%, and the protein concentration was ≤40 mg/L. The absorbance of the decolorized solution was ≤0.021 at 430 nm, and the recovery rate of nylon 54 salt reached 97%. Then, the pretreated solution was passed through sequential chromatographic columns, which effectively removed organic acid by-products (such as acetic acid and lactic acid), SO4 2-, and NH4 + from the fermentation broth, resulting in a cadaverine yield of 98.01% and a succinic acid yield of 89.35%. Finally, by concentrating and crystallizing the eluent, the simulated fermentation broth yielded nylon 54 salt with a purity of 99.16% and a recovery rate of 58%, and the real fermentation broth yielded nylon 54 salt with a purity of 98.10% and a recovery rate of 56.21%. This integrated process offers a sustainable and environmentally friendly pathway for the complete biosynthesis of nylon 54 salt and has the potential to be extended to the preparation of other nylon salts.
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BACKGROUND: Association between glucose and inflammatory bowel disease (IBD) was found in previous observational studies and in cohort studies. However, it is not clear whether these associations reflect causality. Thus, this study investigated whether there is such a causal relation between elevated glucose and IBD, Crohn's disease (CD) and ulcerative colitis (UC). METHODS: We performed a two-sample Mendelian Randomization (MR) with the independent genetic instruments identified from the largest available genome-wide association study (GWAS) for IBD (5,673 cases; 213,119 controls) and its main subtypes, CD and UC. Summarized data for glucose which included 200,622 cases and glycemic traits including HbA1c and type 2 diabetes(T2DM) were obtained from different GWAS studies. Primary and secondary analyses were conducted by preferentially using the radial inverse-variance weighted (IVW) approach. A number of other meta-analysis approach and sensitivity analyses were carried out to assess the robustness of the results. RESULTS: We did not find a causal effect of genetically predicted glucose on IBD as a whole (OR 0.858; 95% CI 0.649-1.135; P = 0.286). In subtype analyses glucose was also suggestively not associated with Crohn's disease (OR 0.22; 95% CI 0.04-1.00; P = 0.05) and ulcerative colitis (OR 0.940; 95% CI 0.628-1.407; P = 0.762). In the other direction, IBD and its subtypes were not related to glucose and glycemic traits. CONCLUSIONS: This MR study is not providing any evidence for a causal relationship between genetically predicted elevated glucose and IBD as well as it's subtypes UC and CD. Regarding the other direction, no causal associations could be found. Future studies with robust genetic instruments are needed to confirm this conclusion.
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Estudo de Associação Genômica Ampla , Doenças Inflamatórias Intestinais , Análise da Randomização Mendeliana , Humanos , Doenças Inflamatórias Intestinais/genética , Glicemia , Polimorfismo de Nucleotídeo Único , Doença de Crohn/genética , Colite Ulcerativa/genética , Diabetes Mellitus Tipo 2/genética , Predisposição Genética para DoençaRESUMO
Nanobubble water promotes the degradation of difficult-to-degrade organic matter, improves the activity of electron transfer systems during anaerobic digestion, and optimizes the composition of anaerobic microbial communities. Therefore, this study proposes the use of nanobubble water to improve the yield of medium chain carboxylic acids produced from cow manure by chain elongation. The experiment was divided into two stages: the first stage involved the acidification of cow manure to produce volatile acidic fatty acids as electron acceptors, and the second phase involved the addition of lactic acid as an electron donor for the chain elongation. Three experimental groups were established, and air, H2, and N2 nanobubble water were added in the second stage. Equal amounts of deionized water were added in the control group. The results showed that nanobubble water supplemented with air significantly increased the caproic acid concentration to 15.10 g/L, which was 55.03 % greater than that of the control group. The relative abundances of Bacillus and Caproiciproducens, which are involved in chain elongation, and Syntrophomonas, which is involved in electron transfer, increased. The unique ability of air nanobubble water supplemented to break down the cellulose matrix resulted in further decomposition of the recalcitrant material in cow manure. This effect subsequently increased the number of microorganisms associated with lignocellulose degradation, increasing carbohydrate metabolism and ATP-binding cassette transporter protein activity and enhancing fatty acid cycling pathways during chain elongation. Ultimately, this approach enabled the efficient production of medium chain carboxylic acids.
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Biodegradação Ambiental , Esterco , Ácidos Carboxílicos/química , Anaerobiose , Animais , Bovinos , Nanoestruturas , Água/química , Ar , Nitrogênio/química , Hidrogênio/química , Transporte de Elétrons , Ácidos Graxos Voláteis/química , ClostridialesRESUMO
A lane-changing (LC) maneuver may cause the follower in the target lane (new follower) to decelerate and give up space, potentially affecting crash risk and traffic flow efficiency. In congested flow, a more aggressive LC maneuver occurs where the lane changer is partially next to the new follower and creates negative gaps, namely negative gap forced LC (NGFLC). Although NGFLC forms the foundation of sideswipe crashes, little has been done to address its impacts and the contributing factors. To tackle this issue, a total of 15,810 LC trajectory samples are extracted from three drone videos at different locations. These samples are categorized into NGFLC and normal LC groups for comparative analysis. Five commonly used conflict indicators are extended into two-dimensional to evaluate the crash risk of LC maneuver. The change of time gaps during LC maneuver are examined to quantify the impact of LC on traffic flow efficiency. We find that NGFLCs significantly increase crash risk, reflected by the number of hazardous LC events and potential crash areas compared to normal LC. Additionally, results reveal that both the lane changer and the new follower tend to maintain a larger time gap after NGFLCs. Factors including time headway, relative speed, and historical gaps in the target lane significantly affect NGFLC incidence. Once the movement of the leader in the original lane is taken into account, the prediction accuracy improves from 81% to 91%. The transferability tests indicate that the findings about the negative impact of NGFLC and the accuracy of its prediction model are consistent across different locations. These findings hold implications for driving assistance systems to better predict and mitigate NGFLCs.
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Acidentes de Trânsito , Condução de Veículo , Acidentes de Trânsito/prevenção & controle , Acidentes de Trânsito/estatística & dados numéricos , Humanos , Segurança , Desaceleração , Planejamento Ambiental , Gravação em VídeoRESUMO
The primary objective of this study was to evaluate the performance of traffic conflict measures for real-time crash risk prediction. Drone recordings were collected from a freeway section in Nanjing, China, over a year. Twenty rear-end crashes and their associated trajectories were obtained. Vehicle trajectories preceding the crash were segmented based on different time periods to represent varying crash conditions. The Extreme Value Theory (EVT) approach combined with a block maxima sampling method was then employed to investigate the generalized extreme value (GEV) distributions of extremely risky events under non-crash and crash conditions. The prediction performance was demonstrated by the differences in GEV distributions under these two conditions. Within the proposed modeling framework, the performances of Time-to-Collision (TTC), Deceleration Rate to Avoid a Crash (DRAC), and Absolute value of Derivative of Instantaneous Acceleration (ADIA) were examined and compared. The results revealed a decreasing trend in the prediction performances as the preceding time window before a crash increased. For any given length of crash conditions, TTC consistently outperformed DRAC and ADIA. Notably, TTC's reliability in crash risk prediction became more uncertain when forecasting crashes more than 2 s in advance. This study provided the optimal thresholds for TTC and ADIA for practical application in crash early warning. The methods and results in this study have the potential to be used for crash risk assessments in autonomous vehicles.
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Aceleração , Acidentes de Trânsito , Desaceleração , Acidentes de Trânsito/estatística & dados numéricos , Acidentes de Trânsito/prevenção & controle , Humanos , China , Medição de Risco/métodos , Condução de Veículo/estatística & dados numéricos , Fatores de Tempo , Previsões/métodosRESUMO
In this study, we designed an artificial pathway composed of tyramine ß-hydroxylase (TBH) and phenylethanolamine N-methyltransferase (PNMT) for the biosynthesis of both octopamine and synephrine. As most TBH and PNMT originate from eukaryotic animals and plants, the heterologous expression and identification of functional TBH and PNMT are critical for establishing the pathway in mode microorganisms like Escherichia coli. Here, three TBHs were evaluated, and only TBH from Drosophila melanogaster was successfully expressed in the soluble form in E. coli. Its expression was promoted by evaluating the effects of different expression strategies. The specific enzyme activity of TBH was optimized up to 229.50 U·g-1, and the first step in the biosynthetic pathway was successfully established and converted tyramine to synthesize 0.10 g/L of octopamine. Furthermore, the second step to produce synephrine from octopamine was developed by screening PNMT, enhancing enzyme activity, and optimizing reaction conditions, with a maximum synephrine production of 2.02 g/L. Finally, based on the optimization of the reaction conditions for each individual reaction, the one-pot cascade reaction for synthesizing synephrine from tyramine was constructed by combining the TBH and PNMT. The synthetic synephrine reached 30.05 mg/L with tyramine as substrate in the two-step enzyme cascade system. With further optimization and amplification, the titers of octopamine and synephrine were increased to 0.45 and 0.20 g/L, respectively, with tyramine as substrate. This work was the first achievement of the biosynthesis of octopamine and synephrine to date.
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Drosophila melanogaster , Escherichia coli , Oxigenases de Função Mista , Octopamina , Feniletanolamina N-Metiltransferase , Sinefrina , Octopamina/metabolismo , Sinefrina/metabolismo , Animais , Drosophila melanogaster/metabolismo , Escherichia coli/metabolismo , Escherichia coli/genética , Feniletanolamina N-Metiltransferase/metabolismo , Feniletanolamina N-Metiltransferase/genética , Oxigenases de Função Mista/metabolismo , Oxigenases de Função Mista/genética , Tiramina/metabolismo , Tiramina/biossíntese , Vias Biossintéticas , Engenharia Metabólica/métodosRESUMO
The development of synthetic microorganisms that could use one-carbon compounds, such as carbon dioxide, methanol, or formate, has received considerable interest. In this study, we engineered Pichia pastoris and Saccharomyces cerevisiae to both synthetic methylotrophy and formatotrophy, enabling them to co-utilize methanol or formate with CO2 fixation through a synthetic C1-compound assimilation pathway (MFORG pathway). This pathway consisted of a methanol-formate oxidation module and the reductive glycine pathway. We first assembled the MFORG pathway in P. pastoris using endogenous enzymes, followed by blocking the native methanol assimilation pathway, modularly engineering genes of MFORG pathway, and compartmentalizing the methanol oxidation module. These modifications successfully enabled the methylotrophic yeast P. pastoris to utilize both methanol and formate. We then introduced the MFORG pathway from P. pastoris into the model yeast S. cerevisiae, establishing the synthetic methylotrophy and formatotrophy in this organism. The resulting strain could also successfully utilize both methanol and formate with consumption rates of 20 mg/L/h and 36.5 mg/L/h, respectively. The ability of the engineered P. pastoris and S. cerevisiae to co-assimilate CO2 with methanol or formate through the MFORG pathway was also confirmed by 13C-tracer analysis. Finally, production of 5-aminolevulinic acid and lactic acid by co-assimilating methanol and CO2 was demonstrated in the engineered P. pastoris and S. cerevisiae. This work indicates the potential of the MFORG pathway in developing different hosts to use various one-carbon compounds for chemical production.
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Dióxido de Carbono , Formiatos , Engenharia Metabólica , Metanol , Saccharomyces cerevisiae , Formiatos/metabolismo , Metanol/metabolismo , Dióxido de Carbono/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomycetales/metabolismo , Saccharomycetales/genéticaRESUMO
BACKGROUND: 1,5-pentanediol (1,5-PDO) is a linear diol with an odd number of methylene groups, which is an important raw material for polyurethane production. In recent years, the chemical methods have been predominantly employed for synthesizing 1,5-PDO. However, with the increasing emphasis on environmentally friendly production, it has been a growing interest in the biosynthesis of 1,5-PDO. Due to the limited availability of only three reported feasible biosynthesis pathways, we developed a new biosynthetic pathway to form a cell factory in Escherichia coli to produce 1,5-PDO. RESULTS: In this study, we reported an artificial pathway for the synthesis of 1,5-PDO from lysine with an integrated cofactor and co-substrate recycling and also evaluated its feasibility in E.coli. To get through the pathway, we first screened aminotransferases originated from different organisms to identify the enzyme that could successfully transfer two amines from cadaverine, and thus GabT from E. coli was characterized. It was then cascaded with lysine decarboxylase and alcohol dehydrogenase from E. coli to achieve the whole-cell production of 1,5-PDO from lysine. To improve the whole-cell activity for 1,5-PDO production, we employed a protein scaffold of EutM for GabT assembly and glutamate dehydrogenase was also validated for the recycling of NADPH and α-ketoglutaric acid (α-KG). After optimizing the cultivation and bioconversion conditions, the titer of 1,5-PDO reached 4.03 mM. CONCLUSION: We established a novel pathway for 1,5-PDO production through two consecutive transamination reaction from cadaverine, and also integrated cofactor and co-substrate recycling system, which provided an alternative option for the biosynthesis of 1,5-PDO.
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Vias Biossintéticas , Escherichia coli , Escherichia coli/metabolismo , Escherichia coli/genética , Engenharia Metabólica/métodos , Glicóis/metabolismo , Lisina/metabolismo , Lisina/biossíntese , Álcool Desidrogenase/metabolismo , Transaminases/metabolismo , Transaminases/genética , Carboxiliases/metabolismoRESUMO
This study aims to investigate the predictability of surrogate safety measures (SSMs) for real-time crash risk prediction. We conducted a year-long drone video collection on a busy freeway in Nanjing, China, and collected 20 rear-end crashes. The predictability of SSMs was defined as the probability of crash occurrence when using SSMs as precursors to crashes. Ridge regression models were established to explore contributing factors to the predictability of SSMs. Four commonly used SSMs were tested in this study. It was found that modified time-to-collision (MTTC) outperformed other SSMs when the early warning capability was set at a minimum of 1 s. We further investigated the cost and benefit of SSMs in safety interventions by evaluating the number of necessary predictions for successful crash prediction and the proportion of crashes that can be predicted accurately. The result demonstrated these SSMs were most efficient in proactive safety management systems with an early warning capability of 1 s. In this case, 308, 131, 281, and 327,661 predictions needed to be made before a crash could be successfully predicted by TTC, MTTC, DRAC, and PICUD, respectively, achieving 75 %, 85 %, 35 %, and 100 % successful crash identifications. The ridge regression results indicated that the predefined threshold had the greatest impact on the predictability of all tested SSMs.
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Acidentes de Trânsito , Acidentes de Trânsito/prevenção & controle , Acidentes de Trânsito/estatística & dados numéricos , Humanos , China , Segurança/estatística & dados numéricos , Medição de Risco/métodos , Gravação em Vídeo , Análise de Regressão , Condução de Veículo/estatística & dados numéricos , PrevisõesRESUMO
In this study, we proposed a biological approach to efficiently produce pseudouridine (Ψ) from glucose and uracil in vivo using engineered Escherichia coli. By screening host strains and core enzymes, E. coli MG1655 overexpressing Ψ monophosphate (ΨMP) glycosidase and ΨMP phosphatase was obtained, which displayed the highest Ψ concentration. Then, optimization of the RBS sequences, enhancement of ribose 5-phosphate supply in the cells, and overexpression of the membrane transport protein UraA were investigated. Finally, fed-batch fermentation of Ψ in a 5 L fermentor can reach 27.5 g/L with a yield of 89.2 mol % toward uracil and 25.6 mol % toward glucose within 48 h, both of which are the highest to date. In addition, the Ψ product with a high purity of 99.8% can be purified from the fermentation broth after crystallization. This work provides an efficient and environmentally friendly protocol for allowing for the possibility of Ψ bioproduction on an industrial scale.
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Proteínas de Escherichia coli , Escherichia coli , Escherichia coli/metabolismo , Pseudouridina/metabolismo , Glucose/metabolismo , Uracila/metabolismo , Reatores Biológicos , Fermentação , Engenharia Metabólica , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Escherichia coli/metabolismoRESUMO
The process of biological fermentation is often accompanied by the release of CO2, resulting in low yield and environmental pollution. Refixing CO2 to the product synthesis pathway is an attractive approach to improve the product yield. Cadaverine is an important diamine used for the synthesis of bio-based polyurethane or polyamide. Here, aiming to increase its final production, a RuBisCO-based shunt consisting of the ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and phosphoribulate kinase (PRK) was expressed in cadaverine-producing E. coli. This shunt was calculated capable of increasing the maximum theoretical cadaverine yield based on flux model analysis. When a functional RuBisCO-based shunt was established and optimized in E. coli, the cadaverine production and yield of the final engineered strain reached the highest level, which were 84.1 g/L and 0.37 g/g Glucose, respectively. Thus, the design of in situ CO2 fixation provides a green and efficient industrial production process.
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Escherichia coli , Ribulose-Bifosfato Carboxilase , Ribulose-Bifosfato Carboxilase/metabolismo , Cadaverina/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Dióxido de Carbono/metabolismo , FermentaçãoRESUMO
5-Hydroxytryptophan (5-HTP), as the precursor of serotonin and melatonin in animals, can regulate mood, sleep, and behavior, which is widely used in pharmaceutical and health products industry. The enzymatic production of 5-hydroxytryptophan (5-HTP) from L-tryptophan (L-Trp) using tryptophan hydroxylase (TPH) show huge potential in application due to its advantages, such as mild reaction conditions, avoidance of protection/deprotection processes, excellent regioselectivity and considerable catalytic efficiency, compared with chemical synthesis and natural extraction. However, the low thermostability of TPH restricted its hydroxylation efficiency toward L-Trp. In this study, we aimed to improve the thermostability of TPH via semi-rational design guided by (folding free energy) ΔΔG fold calculation. After two rounds of evolution, two beneficial mutants M1 (S422V) and M30 (V275L/I412K) were obtained. Thermostability evaluation showed that M1 and M30 possessed 5.66-fold and 6.32-fold half-lives (t1/2) at 37 °C, and 4.2 °C and 6.0 °C higher melting temperature (Tm) than the WT, respectively. The mechanism behind thermostability improvement was elucidated with molecular dynamics simulation. Furthermore, biotransformation of 5-HTP from L-Trp was performed, M1 and M30 displayed 1.80-fold and 2.30-fold than that of WT, respectively. This work provides important insights into the thermostability enhancement of TPH and generate key mutants that could be robust candidates for practical production of 5-HTP.
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5-Hidroxitriptofano , Triptofano Hidroxilase , Animais , 5-Hidroxitriptofano/metabolismo , Triptofano Hidroxilase/genética , Triptofano Hidroxilase/metabolismo , Triptofano/metabolismo , Serotonina/metabolismo , Engenharia de ProteínasRESUMO
Metabolic dysfunctionassociated steatotic liver disease (MASLD) is an increasingly significant global health burden for which there is currently no effective treatment. The present study aimed to explore the underlying mechanisms and investigate the effects of donafenib and atorvastatin in MASLD. The effects of donafenib and atorvastatin on the activity and lipid metabolism of HepG2 cells were analyzed in vitro. A rat model of MASLD was established induced by a highfat diet in vivo. H&E and Oil red O staining were used to observe the improvement in MASLD, western blotting analysis was used to detect the expression of proteins related to fat metabolism and immunofluorescence was used to detect reactive oxygen species (ROS) levels. In vitro, donafenib and atorvastatin inhibited lipid accumulation in HepG2 cells. In vivo, donafenib and atorvastatin activated the AMPactivated protein kinase (AMPK) pathway, downregulated the expressions of proteins related to fatty acid synthesis (sterol regulatory elementbinding protein1, 3hydroxy3methylglutarylCoA reductase and fatty acid synthase) and upregulated the expression of proteins related to fatty acid ßoxidation (carnitine palmitoyltransferase 1C and acylCoA oxidase). The levels of free fatty acids, cholesterol and triglycerides in the liver and serum decreased in all three treatment groups. Additionally, donafenib and atorvastatin reduced oxidative stress in the liver tissue and decreased ROS levels. Lowdose donafenib combined with atorvastatin improved MASLD by regulating fatty acid metabolism and reducing oxidative stress through activation of the AMPK signaling pathway.
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Doenças Metabólicas , Hepatopatia Gordurosa não Alcoólica , Piridinas , Ratos , Animais , Humanos , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/complicações , Proteínas Quinases Ativadas por AMP/metabolismo , Atorvastatina/farmacologia , Atorvastatina/uso terapêutico , Espécies Reativas de Oxigênio/metabolismo , Dieta Hiperlipídica/efeitos adversos , Fígado/metabolismo , Metabolismo dos Lipídeos , Células Hep G2 , Doenças Metabólicas/complicaçõesRESUMO
Fermentation plays a pivotal role in the industrialization of bioproducts, yet there is a substantial lag in the fermentation process regulation. Here, an artificial neural network (ANN) and genetic algorithm (GA) coupled with fermentation kinetics were employed to establish an innovative lysine fermentation control. Firstly, the strategy of coupling GA with ANN was established. Secondly, specific lysine formation rate (qp), specific substrate consumption rate (qs), and specific cell growth rate (µ) were predicted and optimized by ANN-GA. The optimal ANN model adopts a three-layer feed-forward back-propagation structure (4:10:1). The optimal fermentation control parameters are obtained through GA. Finally, when the carbon to nitrogen ratio, residual sugar concentration, ammonia nitrogen concentration, and dissolved oxygen were [2.5, 4.5], [6.5, 9.5] g·L-1, [1.0, 2.0] g·L-1 and [20, 30] %, respectively, the lysine concentration reaches its peak at 213.0 ± 5.10 g·L-1. The novel control strategy holds significant potential for optimizing the fermentation of other bioproducts.
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Algoritmos , Lisina , Fermentação , Redes Neurais de Computação , NitrogênioRESUMO
Remote photoplethysmography (rPPG) is an attractive method for noninvasive, convenient and concomitant measurement of physiological vital signals. Public benchmark datasets have served a valuable role in the development of this technology and improvements in accuracy over recent years. However, there remain gaps in the public datasets. First, despite the ubiquity of cameras on mobile devices, there are few datasets recorded specifically with mobile phone cameras. Second, most datasets are relatively small and therefore are limited in diversity, both in appearance (e.g., skin tone), behaviors (e.g., motion) and environment (e.g., lighting conditions). In an effort to help the field advance, we present the Multi-domain Mobile Video Physiology Dataset (MMPD), comprising 11 hours of recordings from mobile phones of 33 subjects. The dataset is designed to capture videos with greater representation across skin tone, body motion, and lighting conditions. MMPD is comprehensive with eight descriptive labels and can be used in conjunction with the rPPG-toolbox [1]. The reliability of the dataset is verified by mainstream unsupervised methods and neural methods. The GitHub repository of our dataset: https://github.com/THU-CS-PI/MMPD_rPPG_dataset.
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Algoritmos , Pele , Humanos , Reprodutibilidade dos Testes , Fotopletismografia/métodos , Pigmentação da PeleRESUMO
Industrial microbes have become the core of biological manufacturing, which utilized as the cell factory for production of plenty of chemicals, fuels and medicine. However, the challenge that the extreme stress conditions exist in production is unavoidable for cell factory. Consequently, to enhance robustness of the chassis cell lays the foundation for development of bio-manufacturing. Currently, the researches on cell tolerance covered various aspects, involving reshaping regulatory network, cell membrane modification and other stress response. In fact, the strategies employed to improve cell robustness could be summarized into two directions, irrational engineering and rational engineering. In this review, the metabolic engineering technologies on enhancement of microbe tolerance to industrial conditions are summarized. Meanwhile, the novel thoughts emerged with the development of biological instruments and synthetic biology are discussed.
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Bio-based pentamethylene diisocyanate (PDI) is a new type of sustainable isocyanate, which has important applications in coatings, foams, and adhesives. Technical-economic analysis of the PDI distillation process can promote the industrialization of PDI. The thermal analysis of PDI facilitates the smooth running of the simulation process. A new PDI heat capacity prediction method was established. The distillation processes of a crude PDI solution by conventional distillation and double-effect distillation were studied. Countercurrent double-effect distillation showed the best energy-saving effects in all double-effect distillation. However, combined with total annual charge (TAC), parallel double-effect distillation was the optimal method for PDI purification. Parallel double-effect distillation can significantly reduce the TAC of production PDI, which is 33.39% lower than that of the conventional distillation. The study demonstrates a clear economic incentive for reducing the cost of PDI purification by parallel double-effect distillation.
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ß-Nicotinamide mononucleotide is a biologically active nucleotide compound, and its excellent anti-aging activity is widely used in medicine and has multiple functions, making NMN have broad application prospects in the fields of nutrition, health food, and even medicine. Herein, based on the supply of the co-substrate PRPP, we designed and constructed three in vivo NMN synthesis pathways using glucose, xylose, and arabinose as raw materials and Escherichia coli as the host. The best in vivo pathway through whole-cell catalysis was identified. Then, we optimized the cell culture and catalytic conditions of the optimal path to determine the optimal conditions and ultimately obtained an NMN titer of 1.8 mM.
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In this study, co-immobilization of PLP and its dependent enzyme were investigated using a novel type of porous chitin bead (PCB). Crayfish shell was used to prepare PCB via dissolution of it to form beads, followed by the removal of CaCO3 and protein in-situ. Scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller method showed that the PCB had abundant porous structures with deacetylation degree of 33 % and the specific surface area of 35.87 m2/g. Then, the beads are used to co-immobilize pyridoxal 5-phosphate (PLP) and l-lysine decarboxylase fused with chitin-binding protein (SpLDC-ChBD). Laser scanning confocal microscopy revealed that the beads could co-immobilize PLP and SpLDC-ChBD successfully. In addition, a packed bed was also constructed using the PCB containing co-immobilized SpLDC-ChBD and PLP. The substrate conversion remained at 91.09 % after 48 h with 50 g/L l-lysine, which showed good continuous catalysis ability. This study provides a novel method for co-immobilization of enzyme and PLP, as well as develops a new application of waste crustacean shells.
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Astacoidea , Quitina , Animais , Fosfato de Piridoxal , Porosidade , CatáliseRESUMO
Dopamine is high-value compound of pharmaceutical interest, but its industrial scale production mostly focuses on chemical synthesis, possessing environment pollution. Bio-manufacturing has caused much attention for its environmental characteristic. Resting cells were employed to as biocatalysts with extraordinary advantages like offering stable surroundings, the inherent presence of expensive cofactors. In this study, whole-cell bioconversion was employed to convert dopa to dopamine. To increase the titer and yield of dopamine production through whole-cell catalysis, three kinds of aromatic amino acid transport protein, AroP, PheP and TyrP, were selected to be co-expressed. The effects of the concentration of L-dopa, pyridoxal-5'- phosphate (PLP), reaction temperature and pH were characterized for improvement of bioconversion. Under optimal conditions, dopamine titer reached 1.44 g/L with molar yield of 46.3%, which is 6.62 times than that of initial conditions. The catalysis productivity of recombinant E. coli co-expressed L-dopa decarboxylase(DDC) and AroP was further enhanced by repeated cell recycling, which maintained over 50% of its initial ability with eight consecutive catalyses. This study was the first to successfully bioconversion of dopamine by whole-cell catalysis. This research provided reference for whole-cell catalysis which is hindered by cell membrane.