PROCESS BIOCHEMISTRY
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2014
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IF 2.524
Ling Jiang,Bo Wang,Rong-rong Li,Sa Shen,Hong-wei Yu,Li-dan Ye
Enzymatic catalytic promiscuity has received increasing attention in the past decade. In this research, ten enzymes were investigated for the promiscuous activity in catalysis of the Michael addition-cyclization cascade reaction of p -nitrobenzalacetone with 1,3-cyclohexanedione to prepare 2-hydroxy-2-methyl-4-(4-nitrophenyl)-3,4,7,8-tetrahydro-2 H -chromen-5(6 H )-one in anhydrous media, and control experiments were conducted to exclude false positive results. The highest yield (46.1%) was observed with Escherichia coli BioH esterase and the optimal reaction condition was: 1 mmol α,β-unsaturated ketone, 1 mmol 1,3-dicarbonyl compound, 20 mg E. coli BioH esterase, 20 ml N,N-dimethylformamide at 37 °C for 120 h. To preliminarily investigate the mechanism, site-directed mutagenesis was performed on the hydrolysis catalytic triad of BioH, and the results indicated “alternate-site enzyme promiscuity”. When a series of substituted benzalacetones and 1,3-cyclic diketones were used as the reactants, yields of up to 76.3% were achieved. These results imply the potential industrial application of E. coli BioH in the preparation of dihydropyran derivatives.
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SENSORS AND ACTUATORS B-CHEMICAL
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2016
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IF 4.758
Xuecheng Sun,Chong Lei,Lei Guo,Yong Zhou
Herein we report a new separable detection system combining magnetic nanoparticle labels with giant magnetoresistance (GMR) first time developed for Escherichia coli (E. coli) O157H:H7 detection. The GMR sensor fabricated employing standard microfabrication technique, while double antibody sandwich immunoassay and streptavidin–biotin binding assay were employed for immobilizing and labeling E. coli O157H:H7 on Au-film coated glass wafer. The GMR-based immunosensor detected E. coli O157H:H7 antigens at different sample concentrations with a minimum detectable limit of 100 CFU/mL, well accepted for early detection in clinical diagnosis and environmental monitoring. Compared with the recently reported GMR sensor based detection methods, this newly developed separable detection method possesses several advantages such as convenient manipulation, avoid being contaminated and damaged by chemical solution and reusability without cleaning. So it is of considerable interest towards the biomedical application based on known specific binding of target and labels.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2017
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IF 3.154
Qinglin He,Hua Yin,Jingjie Jiang,Yanfen Bai,Ning Chen,Shaowei Liu,Yibin Zhuang,Tao Liu
Three rosmarinic acid analogs produced by recombinant Escherichia coli, two xanthones from fungi and honokiol from plants, were explored as the substrates of E. coli harboring a glucosyltransferase mutant UGT73B6FS to generate phenolic glucosides. Six new and two known compounds were isolated from the fermentation broth of the recombinant strain of the feeding experiments, and the compounds were identified by spectroscopy. The biotransformation of rosmarinic acid analogs and xanthones into corresponding glucosides was presented for the first time. This study not only demonstrated the substrate flexibility of the glucosyltransferase mutant UGT73B6FS toward aromatic alcohols but also provided an effective and economical method to produce phenolic glucosides by fermentation circumventing the use of expensive precursor UDP-glucose.
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Antibiotics-Basel
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2024
·Vol. 13
·期 6
·528
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IF 4.3
Muchen Zhang,Huangwei Song,Siyuan Yang,Yan Zhang,Yunrui Tian,Yang Wang,Dejun Liu
The emergence of carbapenem-resistant Gram-negative pathogens presents a clinical challenge in infection treatment, prompting the repurposing of existing drugs as an essential strategy to address this crisis. Although the anticancer drug 5-fluorouracil (5-FU) has been recognized for its antibacterial properties, its mechanisms are not fully understood. Here, we found that the minimal inhibitory concentration (MIC) of 5-FU againstEscherichia coliwas 32–64 µg/mL, including strains carryingblaNDM-5, which confers resistance to carbapenems. We further elucidated the antibacterial mechanism of 5-FU againstE. coliby using genetic and biochemical analyses. We revealed that the mutation of uracil phosphoribosyltransferase-encoding geneuppincreased the MIC of 5-FU againstE. coliby 32-fold, indicating the role of theuppgene in 5-FU resistance. Additionally, transcriptomic analysis ofE. colitreated with 5-FU at 8 µg/mL and 32 µg/mL identified 602 and 1082 differentially expressed genes involved in carbon and nucleic acid metabolism, DNA replication, and repair pathways. The biochemical assays showed that 5-FU induced bacterial DNA damage, significantly increased intracellular ATP levels and the NAD+/NADH ratio, and promoted reactive oxygen species (ROS) production. These findings suggested that 5-FU may exert antibacterial effects onE. colithrough multiple pathways, laying the groundwork for its further development as a therapeutic candidate against carbapenem-resistant bacterial infections.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
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2025
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IF 3.3
Guo Jing,Cui Jiayi,Xun Mingyue,Zhang Wencheng,Xian Mo,Zhang Rubing
L- threo -3-hydroxyaspartic acid (L-THA) is a non-proteinogenic amino acid that has garnered significant attention due to its diverse biological activities. However, the synthesis of L-THA through enzymatic and whole-cell catalysis requires the expensive substrate L-aspartic acid or L-asparagine, and co-substrate α-ketoglutarate, which limits their large-scale application. Here, this is the first report of engineering E. coli as a cell factory for de novo production of L-THA from glucose by fermentation. Firstly, the asnO gene encoding asparagine hydroxylases from Streptomyces coelicolor was heterologously expressed in E. coli to yield the L-THA producing strain. The formation and configuration of L-THA were characterized by LC–MS and HPLC after FDAA derivatization. Secondly, the pathway genes aspC and asnB , which encode aspartate aminotransferase and asparagine synthase, respectively, were overexpressed to enhance L-THA titer from 49.9 to 90.84 mg/L. Thirdly, the efforts were made to improve the key precursor L-aspartic acid pool by overexpressing the aspartase encoding gene aspA and knocking out aspartate kinase (AK) III encoding gene lysC . The best strain CC03 was obtained and L-THA titer reached 278.3 mg/L in a shake flask, representing an approximately 5.6-fold increase compared to the original strain. Ultimately, 2.87 g/L L-THA was obtained after 32 h fed-batch fermentation. This research underscores the potential use of E. coli fermentation as a feasible platform for de novo biosynthesis of L-THA from glucose, which is amenable to industrial application.
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BIORESOURCE TECHNOLOGY
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2025
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IF 9
Xin Jin,Sumeng Wang,Yaping Gao,Qingsheng Qi,Quanfeng Liang
Background The industrial production of L-threonine faces challenges because of high production costs, especially those of substrates, meaning new production methods are needed. Methods Fur, a new global transcription factor related to L-threonine biosynthesis, was discovered in this study. Multidimensional regulation combined with global transcriptional machinery engineering was used to modify an Escherichia coli strain. Results: The most efficient mutant showed high titer (154.2 g/L), productivity (2.14 g/L/h), and yield (0.76 g/g) of L-threonine production. These three parameters indicated that these engineering strategies were economically feasible for developing high L-threonine-producing strains. We integrated the sucrose utilization gene cluster into the genome to further reduce the production cost of L-threonine. Using untreated cane molasses as the substrate, L-threonine was successfully produced with a titer of 92.46 g/L and a cost reduction of 48 %. Conclusion This research offers advantages for industrial scalability, and the resulting engineered bacterium holds significant industrial application potential.
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METABOLIC ENGINEERING
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2024
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IF 6.8
Yajing Zhang,Tao Sun,Linqi Liu,Xupeng Cao,Weiwen Zhang,Wangyin Wang,Can Li
Microbial CO 2 fixation into lactic acid (LA) is an important approach for low-carbon biomanufacturing. Engineering microbes to utilize CO 2 and sugar as co-substrates can create efficient pathways through input of moderate reducing power to drive CO 2 fixation into product. However, to achieve complete conservation of organic carbon, how to engineer the CO 2 -fixing modules compatible with native central metabolism and merge the processes for improving bioproduction of LA is a big challenge. In this study, we designed and constructed a solar formic acid/pentose (SFAP) pathway in Escherichia coli , which enabled CO 2 fixation merging into sugar catabolism to produce LA. In the SFAP pathway, adequate reducing equivalents from formate oxidation drive glucose metabolism shifting from glycolysis to the pentose phosphate pathway. The Rubisco-based CO 2 fixation and sequential reduction of C3 intermediates are conducted to produce LA stoichiometrically. CO 2 fixation theoretically can bring a 20% increase of LA production compared with sole glucose feedstock. This SFAP pathway in the integration of photoelectrochemical cell and an engineered Escherichia coli opens an efficient way for fixing CO 2 into value-added bioproducts.
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Bioresources and Bioprocessing
·
2024
·Vol. 11
·期 1
·1-10
·
IF 4.3
Wang Cong,Chang Dongdong,Zhang Qi,Yu Zhisheng
Lignocellulose pretreated using pyrolysis can yield clean energy (such as bioethanol) via microbial fermentation, which can significantly contribute to waste recycling, environmental protection, and energy security. However, the acids, aldehydes, and phenols present in bio-oil with inhibitory effects on microorganisms compromise the downstream utilization and conversion of lignocellulosic pyrolysates. In this study, we constructed a microbial electrolysis cell system for bio-oil detoxification and efficient ethanol production using evolved Escherichia coli to overcome the bioethanol production and utilization challenges highlighted in previous studies. In electrically treated bio-oil media, the E. coli-H strain exhibited significantly higher levoglucosan consumption and ethanol production capacities compared with the control. In undetoxified bio-oil media containing 1.0% (w/v) levoglucosan, E. coli-H produced 0.54 g ethanol/g levoglucosan, reaching 94% of the theoretical yield. Our findings will contribute to developing a practical method for bioethanol production from lignocellulosic substrates, and provide a scientific basis and technical demonstration for its industrialized application.
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FOOD CHEMISTRY
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2025
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IF 9.8
Mengxue Diao,Ziwei Li,Runhao Zhou,Xiaoxia Yan,Tiehua Zhang
Thymol showed good antimicrobial activity, however, the poor aqueous solubility limits it to apply in food industry. α-Lactalbumin can be used to delivery hydrophobic molecules, then enhancing their biological activities. The study investigates the potential of α-lactalbumin to expand the application range of thymol, further to evaluate the antimicrobial activity of the α-lactalbumin-thymol complexation. Multi-spectroscopy techniques and computational simulations have confirmed the successful complexation, driving mainly by van der Waals force. The α-lactalbumin-thymol complexation exhibited the superior antimicrobial activity than thymol against Escherichia coli and Staphylococcus aureus , as indicated by lower or comparable minimum inhibitory concentration (336 μg/mL and 224 μg/mL, respectively), fewer colony forming units, and larger inhibition zone diameters. Furthermore, α-lactalbumin enhanced the degree of membrane damage by thymol. The complexation preserved no obvious cytotoxicity against HeLa cells. This study indicates that the α-lactalbumin-thymol complexation chelates hold promise as natural antimicrobial agents in the food processing industry.
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ARCHIVES OF MICROBIOLOGY
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2024
·Vol. 206
·期 12
·1-13
·
IF 2.3
Zhai Yafei,Wang Yuhao,Wang Bohua,Niu Liyuan,Xiang Qisen,Bai Yanhong
Dielectric barrier discharge (DBD) plasma can be used to control food spoilage and food pathogens. However, DBD plasma may induce sublethal injury in microorganisms, constituting a considerable risk to food safety. This research was designed to investigate the sublethal injury and recovery of Escherichia coli O157:H7 after DBD plasma treatment. The results indicated that the sublethal injury ratios of cells rose along with the augmentation of treatment time and input power of DBD plasma under mild treatment conditions, whereas injury accumulation ultimately culminated in cell death. The highest sublethal ratio of 99.3% was obtained after DBD plasma treatment at 18 W for 40 s. When solutions such as phosphate buffered saline (PBS), peptone water, glucose solution, and tryptic soy broth (TSB) were used for cell recovery, TSB was proven to be the most efficacious, facilitating the completion of recovery within 2 h. The repair ratio of injured cells increased as the recovery pH (3.0–7.0) and temperature (4–37 ºC) increased. Moreover, Mg 2+ and Zn 2+ were demonstrated to be necessary for the recovery process, while Ca 2+ presented a weak effect. Understanding the sublethal injury of bacteria resulting from DBD plasma treatment and their repair conditions can provide useful insight into avoiding the occurrence of sublethal injury as well as inhibiting the occurrence of recovery during food processing and storage.
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JOURNAL OF CONTROLLED RELEASE
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2017
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IF 7.786
Songzhi Xie,Long Zhao,Xiaojie Song,Maosheng Tang,Chuanfei Mo,Xiaohong Li
The use of bacteria as drug carriers meets several challenges, such as biocompatibility, motility deterioration after drug loading and lack of in vivo verification. Escherichia coli Nissle 1917 (EcN) is one of the best studied probiotic strains, and doxorubicin (DOX) is conjugated onto EcN in the current study via acid-labile linkers of cis -aconitic anhydride (EcN-ca-Dox), realizing the bacteria-directed accumulation and acid-responsive release of anticancer drugs in tumors. The drug conjugation has maintained the bacterial motion profiles of over 9 μm/s and cell viability of over 70%. After 3 h and 3 days of intravenous injection of EcN-ca-Dox, DOX accumulations in tumors are determined as 12.9% and 6.4% of the injected doses per gram of tissue, respectively, which are much higher than the commonly used nanocarriers . Compared with free DOX and DOX-conjugated EcN via stable linkers of succinic anhydride , the EcN-ca-Dox treatment improves the antitumor efficacy with respect to the tumor growth inhibition, prolongation of animal survivals, and apoptosis induction of tumor cells. In addition, EcN has been cleaned off from tumors and other tissues after antimicrobial treatment. Thus, the acid-labile EcN conjugates provide a safe and concise strategy to enhance the temporal and spatial controllability of anticancer drugs.
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BIOCHEMICAL ENGINEERING JOURNAL
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2021
·
IF 3.978
Yiwei Dai,Chenchen Li,Luhua Zheng,Bo Jiang,Tao Zhang,Jingjing Chen
In our previous study, a whole-cell biocatalytic system involving α-glucan phosphorylase , phosphoglucomutase , glucose 6-phosphate isomerase, tagatose 1,6-bisphosphate aldolase , and phosphoglycolate phosphatase , was constructed to produce d -tagatose from maltodextrin . However, the biotransformation efficiency of this whole-cell catalyst was low because of the unbalanced ratio of each enzyme and metabolic flux of the intermediates. Therefore, in this study, the biosynthesis of d -tagatose was enhanced by optimizing vectors and improving the expression of rate-limiting enzymes through the construction of multi-copy genes to regulate expression levels. The conversion rate increased from 20.8% after 24 h to 25.2% after 3 h using 10 g/L maltodextrin as the substrate. Furthermore, the genes in the bypass pathways in Escherichia coli , pfka and zwf , were deleted to increase the accumulation of intermediates. The strain ER-2GatZ (Δ p Δ z ) produced 3.383 g/L d -tagatose using 10 g/L substrate after 3 h, which was 1.34 times that of the wild strain. This work exemplifies the use of modular engineering to enhance d -tagatose production using whole-cell catalysts.
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