CHEMICAL ENGINEERING JOURNAL
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2026
·
IF 12.5
Guihong Zhao,Siyu Tian,Yuhang Li,Weixuan Dong,Hao Jiang,Jiaxiang Kuang,Feiao Wang,Sijia Li,Yanjun Li
Engineered autonomous ethylamine biosynthesis via dual-pathway strategy, eliminating the need for exogenous ethylamine. • Achieved record-breaking L-theanine titer of 118.2 g/L in fed-batch fermentation, the highest reported production to date. • Elucidated the ethylamine preference mechanism of L-theanine synthetase Mm GMAS, providing insights for enzyme engineering. • Developed systematic metabolic engineering combining precursor enhancement, pathway knockout, and adaptive evolution. L-Theanine, the most abundant free amino acid in tea, is a non-proteinogenic amino acid widely used in food and cosmetics, with documented health benefits and therapeutic potential. To circumvent the reliance on hazardous exogenous ethylamine in L-theanine production, we engineered an integrated and efficient strategy for high-level L-theanine production in Escherichia coli via dual-pathway ethylamine biosynthesis. First, by enhancing the expression and elucidating the ethylamine preference mechanism of the L-theanine synthetase Mm GMAS, the obtained strain THE-3 produced 15.8 g/L L-theanine. Building on this, the knock-out of L-theanine degradation pathway combined with bolstered precursors supply further increased the titer to 16.8 g/L and 22.8 g/L in strain THE-6 and THE-9, respectively. Then, developing the ethylamine intracellular biosynthesis via Cs AlaDC-mediated decarboxylation pathway in THE-13 resulted in the production of 19.5 g/L L-theanine and 5.4 g/L L-alanine without exogenous ethylamine. Subsequently, by synergizing the Pp SpuC-mediated transamination pathway with L-alanine as the amino donor, and subjecting this strain to evolution for acetaldehyde resistance, the final engineered strain, THE-17, achieved a record-breaking titer of 118.2 g/L in fed-batch fermentation, with a yield of 0.389 g/g glucose and a productivity of 2.46 g/L/h. This study establishes the highest reported L-theanine production to date and provides a transformative approach for industrial L-theanine production, shifting the paradigm from reliance on exogenous ethylamine addition to autonomous ethylamine supply.
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Frontiers in Plant Science
·
2023
·
IF 5.6
Xiaopeng Lu,Qiong Wu,Keyi Nie,Hua Wu,Guangyou Chen,Jun Wang,Zhiqing Ma
Drought stress (DS) is one of the main abiotic negative factors for plants. Phthalanilic acid (PPA), as a plant growth regulator, can promote the growth and development of crops. In order to evaluate the ideal application concentration and frequency of PPA-induced drought resistance in pepper ( Capsicum annuum ) seedlings, the concentration of PPA was 133.3 mg·L −1 ; 200.0 mg·L −1 ; 266.7 mg·L −1 , and some key indicators were investigated, including leaf wilting index (LWI), relative water content (RWC), and malondialdehyde (MDA). We found that the LWI and RWC in the PPA-applied pepper leaves under light drought stress (LDS) and moderate drought stress (MDS) were all elevated, while MDA contents were decreased. To better understand how PPA makes pepper drought resistant, we examined the photosynthetic characteristics, growth parameters, antioxidant activities, and osmotic substances in pepper seedlings treated twice with PPA at a concentration of 133.3 mg·L −1 under LDS, MDS, and severe drought stress (SDS). Results showed that PPA increased the chlorophyll, plant height, stem diameter, root-shoot ratio, and seedling index of pepper leaves under LDS, MDS, and SDS. The net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO 2 concentration (Ci), transpiration rates (Tr), and water-use efficiency (WUE) in the PPA-treated pepper leaves under LDS and MDS were improved, while their stomatal limitation (Ls) were reduced. PPA also boosted the activities of enzymatic antioxidants (superoxide dismutase, catalase, and peroxidase), as well as enhanced the accumulation of osmotic substances such as soluble sugar, soluble protein, and free proline in pepper leaves under LDS, MDS, and SDS. Thus, PPA can alleviate the growth inhibition and damage to pepper seedlings caused by DS, and the PPA-mediated efficacy may be associated with the improvement in PPA-mediated antioxidant activities, Pn, and accumulation of osmotic substances.
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CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2023
·
IF 3.9
Nor Hafiza Ismail,Wan Norharyati Wan Salleh,Farhana Aziz,Norhaniza Yusof,Juhana Jaafar,Ahmad Fauzi Ismail,Ahmad Hafizal Mohd Yamin
Oily wastewater poses a significant environmental concern as it has adverse effects on both ecosystems and human health. The development of highly efficient and robust antifouling membranes for oily emulsion is in great demand to prevent these serious issues in oil/water emulsion filtration. Moreover, fouling was inevitable when dealing with membrane separation . In order to overcome the addressed matters, this paper reported sprayed hydrophilic surface coating using commercialized levodopa ( L -DOPA). The coated solution was mixed with 3-amino-propyltriethoxysilane in various ratios to obtain a smooth coated layer. Based on the results, the highest pure water flux and rejection efficiency of 586.51 ± 23.95 L/m 2 ‧h and 98.22% was achieved in this study, respectively. The abundant hydroxyl and carboxyl functional groups on the membrane surface from L -DOPA benefit the membrane in many ways, especially the membrane wetting properties. The water and oil contact angles of the coated membrane increased by approximately 75% and 85%, respectively. The fouling behaviors are influenced by the presence of the coated layer, resulting in the attainment of 90% fouling resistance ratio (FRR). This is mostly due to the reduction in adherence of oil droplets on the membrane surface, hence enhancing the effectiveness of the anti-oil fouling membrane . Additionally, this provides excellent properties of the membrane to be applied in oily wastewater treatment .
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ENVIRONMENTAL TECHNOLOGY
·
2023
·
IF 2.8
Tuqiao Zhang,Rongrong Jiang,Lei Fang,Xiaowei Liu,Lijie Jiang
The presence of metal ions in drinking water treatment and distribution systems may affect the disinfection process of organic matter, which had aroused people's concern. L-tyrosine can complex with metal ions through carboxyl, carbonyl, and amino groups and affect its chemical reactions. In this paper, the complexation of L-tyrosine with common metal ions was studied and the influence of complexation on chlorination with different experimental factors was investigated. It was inferred that L-tyrosine complexed with metal ions by single dentate ligand or double dentate chelation in a ratio of 2:1. The degradation of L-tyrosine-metal complex followed the pseudo-first-order reaction kinetic. TCM, DCAA, and TCAA were the main species DBPs in the chlorination of L-tyrosine. Compared with L-tyrosine, the reaction rate constants of complex increased by 5.6%, the formation of trihalomethane production decreased by 21.5% and the formation of haloacetic acids production increased by 26.9% at the state of metal complexation. The effect of metal complexation on chlorination was more obvious than that of metal coexistence. For different metal complexation, the order of inhibition on trihalomethane production was Ca2+> Fe3+> Mn2+ and the order of promotion on haloacetic acids production was Mn2+> Fe3+> Ca2+. Moreover, it was found that alkaline conditions were favorable for the formation of DBPs due to the hydroxyl radical. The combination of ultraviolet and chlorine disinfection promoted L-Tyrosine degradation and DBPs generation, and the promotion efficiency follow the order: UV/Cl2> UV-Cl2> Cl2.
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JOURNAL OF NUTRITION
·
2023
·
IF 4.2
Luyuan Kang,Jiaman Pang,Xiangyu Zhang,Yisi Liu,Yujun Wu,Junjun Wang,Dandan Han
Background L-arabinose has anti-inflammatory and metabolism-promoting properties, and macrophages participate in the alleviation of inflammation; however, the mechanism by which they contribute to the anti-inflammatory effects of L-arabinose is unknown. Objectives To investigate the involvement of macrophages in the mitigation of L-arabinose in an intestinal inflammation model induced by lipopolysaccharide (LPS). Methods Five-week-old male C57BL/6 mice were divided into 3 groups: a control and an LPS group that both received normal water supplementation, and an L-arabinose (ARA+LPS) group that received 5% L-arabinose supplementation. Mice in the LPS and ARA+LPS groups were intraperitoneally injected with LPS (10 mg/kg body weight), whereas the control group was intraperitoneally injected with the same volume of saline. Intestinal morphology, cytokines, tight junction proteins, macrophage phenotypes, and microbial communities were profiled at 6 h postinjection. Results L-arabinose alleviated LPS-induced damage to intestinal morphology. L-arabinose down-regulated serum tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, and messenger RNA (mRNA) levels of TNF-α , IL-1β , interferon-γ ( IFN-γ ), and toll-like receptor-4 in jejunum and colon compared with those of the LPS group ( P < 0.05). The mRNA and protein levels of occludin and claudin-1 were significantly increased by L-arabinose ( P < 0.05). Interferon regulatory factor-5 ( IRF-5 ) and signal transducer and activator of transcription-1 ( STAT-1 ), key genes characterized by M1 macrophages, were elevated in the jejunum and colon of LPS mice ( P < 0.05) but decreased in the ARA+LPS mice ( P < 0.05). In vitro , L-arabinose decreased the proportion of M1 macrophages and inhibited mRNA levels of TNF-α , IL-1β , IL-6 , IFN-γ , as well as IRF-5 and STAT-1 ( P < 0.01). Moreover, L-arabinose restored the abundance of norank_ f__Muribaculaceae , Faecalibaculum , Dubosiella , Prevotellaceae_UCG-001 , and Paraasutterella compared with those of LPS ( P < 0.05) and increased the concentration of short-chain fatty acids ( P < 0.05). Conclusion The anti-inflammatory effects of L-arabinose are achieved by reducing M1 macrophage polarization, suggesting that L-arabinose could be a candidate functional food or nutritional strategy for intestinal inflammation and injury.
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CARBOHYDRATE POLYMERS
·
2021
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IF 9.381
Chunling Nie,Ting Shen,Weicheng Hu,Qin Ma,Jiahui Zhang,Shuqian Hu,Huafeng Tian,Hao Wu,Xiaogang Luo,Jianguo Wang
In recent years, harmful microorganisms in water pose great harm to ecological environment and human health. To solve this problem, epsilon-poly- l -lysine (EPL) grafted cellulose beads were prepared via 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidation and carbodiimide mediated cross-linking reaction. Hydroxyl groups on C6 of cellulose were oxidized to carboxyl groups by TEMPO and grafting reaction was achieved between newly formed carboxyl groups of cellulose and amino of EPL. The beads were characterized by FTIR, SEM, XRD and TGA. The crystalline form of cellulose transformed from cellulose I to cellulose II after being dissolved and regenerated. The grafted cellulose beads showed good antibacterial activities against Gram-negative Escherichia coli , Gram-positive Staphylococcus aureus and Alicyclobacillus acidoterrestris with 10 h. The beads could be biodegraded in soil after 28 days. It is expected that the bio-based composite beads could have potential applications in water purification and food treatment fields.
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Bioresources and Bioprocessing
·
2021
·Vol. 8
·期 1
·1-15
·
IF 4.578
Tan Xu,Zhang Sheng,Song Wei,Liu Jia,Gao Cong,Chen Xiulai,Liu Liming,Wu Jing
In this study, a four-enzyme cascade pathway was developed and reconstructed in vivo for the production of d - p -hydroxyphenylglycine (D-HPG), a valuable intermediate used to produce β-lactam antibiotics and in fine-chemical synthesis, from l -tyrosine. In this pathway, catalytic conversion of the intermediate 4-hydroxyphenylglyoxalate by meso -diaminopimelate dehydrogenase from Corynebacterium glutamicum ( Cg DAPDH) was identified as the rate-limiting step, followed by application of a mechanism-guided “conformation rotation” strategy to decrease the hydride-transfer distance d (C6HDAP−C4NNADP) and increase Cg DAPDH activity. Introduction of the best variant generated by protein engineering ( Cg DAPDH BC621/D120S/W144S/I169P with 5.32 ± 0.85 U·mg −1 specific activity) into the designed pathway resulted in a D-HPG titer of 42.69 g/L from 50-g/L l -tyrosine in 24 h, with 92.5% conversion, 71.5% isolated yield, and > 99% enantiomeric excess in a 3-L fermenter. This four-enzyme cascade provides an efficient enzymatic approach for the industrial production of D-HPG from cheap amino acids.
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JOURNAL OF CHROMATOGRAPHIC SCIENCE
·
2021
·Vol. 59
·期 4
·388-395
·
IF 1.618
Ma Xiaofei,Li Jingtang,Li Xiaoqi,Feng Zijie,Yang Xuan,Liu Jie,Du Yingxiang
Nowadays, ionic liquids (ILs) functionalized cyclodextrins (CDs) have drawn increasing attention in chiral separation. Herein, a novel β-CD derivative functionalized by L-histidinium IL, mono-6-deoxy-6-L-histidinium-β-cyclodextrin chloride (L-HMCDCl), was synthesized for the first time and utilized for enantioseparation of nefopam and chlorphenamine in capillary electrophoresis. The L-HMCDCl exhibited superior enantioselectivity compared with native β-CD. The effect of some key parameters such as chiral selector concentration, buffer pH and applied voltage on the enantioseparation was investigated in detail. In the interest of the chiral discrimination mechanism and the enhanced enantioselectivity of L-HMCDCl, molecular modeling with AutoDock was employed to study the interaction, which was in good agreement with experimental results.
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Science China-Chemistry
·
2020
·Vol. 63
·期 9
·1295-1305
·
IF 6.356
Wang Xianheng,Yang Lei,Yang Peng,Guo Wancai,Zhang Quan-Ping,Liu Xianhu,Li Yiwen
Melanin-inspired polymers are currently the focus of growing interest for a wide range of applications ranging from energy to biomedical area. Whilst researchers have made numerous attempts to prepare and utilize polydopamine nanoparticles (PDA NPs), they have made limited progress in developing and discovering another typical functional mimic of natural melanin, poly (levodopa) (P(L-DOPA)) NPs, probably due to the lack of facile synthetic strategies towards satisfactory structural and functional control of melanin-like NPs. Herein, we reported a one-pot preparation method towards P(L-DOPA) NPs with good yields and controllable size/property in an aqueous solution assisted by various metal ions ( i.e. , Ni(II), Mg(II), Ca(II), Fe(III), Mn(II), Co (II), Zn(II) and Cd(II)). Interestingly, the resulting P(L-DOPA) NPs exhibited enhanced light absorption and photothermal behaviors compared with well-established PDA NPs, which can be employed to further fabricate kinds of photothermal composite actuators with promising performances such as folding, switching, and forward-moving. This study offers a facile and robust way to synthesize new synthetic melanins beyond PDA, and facilitates further functional discovery and evolution of melanin-inspired polymers and composites.
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TOXICON
·
2020
·
IF 2.201
Qing Cao,Weijing Liu,Yurong Gu,Liqiang Xie,Weili Jiang,Yan Gao,Liuyan Yang
Heavy metals and microcystins commonly co-exist in water bodies with cyanobacteria, and have been shown to affect aquatic plants. However, their combined effects remain largely unknown. In this study, the toxic effects of copper (Cu) and cadmium (Cd) on Ceratophyllum demersum L. were characterized in the presence of microcystin-LR (MC-LR). The results showed that the bioaccumulation of MC-LR and Cu/Cd in C. demersum was significantly increased by the interaction between MC-LR and Cu/Cd. The combined toxicity assessment results suggested that the toxicities of Cu or Cd to C. demersum would be largely exacerbated by MC-LR, which could be the results of increased bioaccumulation of the pollutants. Cu, Cd and MC-LR, as well as their mixture, significantly decreased plant fresh weight and total chlorophyll content of C. demersum , especially at their high concentrations. The antioxidative system was activated to cope with the adverse effects of oxidative stress. Antioxidant enzyme activities were significantly stimulated by Cu, Cd and MC-LR, as well as their mixture. However, the decreased superoxide dismutase (SOD) and glutathione reductase (GR) activities were observed when exposed to relative high concentrations of Cu or Cd together with MC-LR of 5 μg L −1 . MC-LR brought more stress to the antioxidative system, which is another possible explanation for the synergistic effect. Our findings highlight increased ecological risks of the co-contamination of heavy metals and harmful cyanobacteria.
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ACS Biomaterials Science & Engineering
·
2020
·
IF 4.152
Bo Li,Ying Chen,Jisu He,Jing Zhang,Song Wang,Wenqian Xiao,Zhongning Liu,Xiaoling Liao
Nanofibrous poly(l-lactic acid) (PLLA) membrane-simulated extracellular matrices (ECMs) can be used in the biomedical field. However, the hydrophobic nature and poor osteoinductive property of PLLA limit its application in guided bone regeneration (GBR). In this work, a methacrylated gelatin/nano-HA (GelMA/nHA) complex was first synthesized in situ and then introduced into PLLA to fabricate biomimetic GelMA/nHA/PLLA membranes, mimicking the nanofibrous architecture and composition of ECMs by electrospinning and photocrosslinking. Compared to PLLA and GelMA/PLLA membranes, the novel GelMA/nHA/PLLA membranes demonstrated better tensile, hydrophilic, water sorption, and degradation properties. An in vitro biological evaluation indicated that the membranes promoted human bone marrow-derived mesenchymal stem cell (hBMSC) proliferation, adhesion, and osteogenic differentiation. Critical-sized defects in rat models were used to evaluate the bone regeneration performances of the three kinds of membranes in vivo, and the GelMA/nHA/PLLA membranes demonstrated excellent osteogenic regeneration potential. Therefore, GelMA/nHA/PLLA membranes have wide application prospects in bioengineering applications such as GBR treatment.
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2020
·Vol. 104
·期 23
·10005-10018
·
IF 3.53
Guo Xiaolei,Wu Weibin,Zhang Mingliang,Wu Licheng,Huang Jianzhong
Abstract l -Tyrosine is a versatile compound used in the fine chemical, pharmaceutical, and functional food industries. Here, we report a bi-enzymatic cascade involving alanine racemase (ALR) and d -amino acid oxidase (DAAO) to produce pyruvate, as co-substrate for l -tyrosine production, from the cheap substrate l -alanine. The BpALR (ALR from Bacillus pseudofirmus ) was used as a whole-cell biocatalyst, converting l -alanine to d , l -alanine. The FsDAAO (DAAO from Fusarium solani ) was immobilized to oxidize the d -alanine generated in the first step to pyruvate. Both systems were combined as a continuous-flow reactor for maximized l -alanine-to-pyruvate conversion rates. The optimal parameters and appropriate conditions for FsDAAO immobilization were investigated. The pyruvate concentration of 86.6 g/L was achieved within 17 h. Subsequently, a whole-cell biocatalyst system for l -tyrosine production, catalyzed by the tyrosine phenol-lyase (TPL) from Erwinia herbicola (EhTPL), was developed, and a fed-batch approach was applied with phenol and the pyruvate produced with the ALR/DAAO system mentioned above. The concentration of phenol and pyruvate in the reactor should not exceed 7.5 g/L and 10 g/L, respectively. Significantly, the l -tyrosine concentration of 152.5 g/L was achieved within 10 h, demonstrating the great potential for high-efficiency production of l -tyrosine through the approach we established in this paper. Graphical abstract Key points • A specific bioreactor system for pyruvate produced from l -alanine was developed • The appropriate condition for immobilization of FsDAAO was investigated • A fed-batch process was established to produce l -tyrosine with recombinant E. coli • The bi-enzymatic cascade was successfully used for l -tyrosine production at low cost
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