LANGMUIR
·
2023
·
IF 3.9
Lingling Zhao,Yue Ma,Zhaomeng Sun,Xiaoqing Zhang,Mei Liu
Bacterial infections and antibiotic abuse are a global threat to human health. In recent years, there has been a boom in research on antimicrobial agents with low toxicity and efficient nanomaterials. Boric acid-functionalized carbon dots (B-CDs) with negative surface charge were synthesized by the hydrothermal method. Covalent bonds were formed between the boric acid groups and the cis-diol groups of the polysaccharide in the bacterial cell wall, and numerous B-CDs were trapped on the bacterial surface. In the experiments of antibacterial activity, B-CDs presented strong bactericidal activity against Escherichia coli (E. coli) with a minimum bactericidal concentration of 12.5 μg/mL. The antibacterial mechanism suggested that B-CDs entered the cell interior by diffusion and posed significant damage to the double helix structure of E. coli DNA. Furthermore, B-CDs exhibited low toxicity. The results demonstrated that the novel antimicrobial B-CDs not only fought against E. coli infection and antibiotic misuse but also provided new ideas for safe and effective antimicrobial agents of carbon nanomaterials.
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高影响因子
VETERINARY RESEARCH
·
2023
·Vol. 54
·期 1
·1-12
·
IF 4.4
Fu Shaodong,Wang Zhenglei,Han Xiangan,Xu Yuanyuan,Miao Jinfeng
Macrophages play a pivotal role in the inflammatory response to the zoonotic pathogen E. coli, responsible for causing enteric infections. While considerable research has been conducted to comprehend the pathogenesis of this disease, scant attention devoted to host-derived H2S. Herein, we reported that E. coli infection enhanced the expression of CSE in macrophages, accompanied by a significantly increased inflammatory response. This process may be mediated by the involvement of excessive autophagy. Inhibition of AMPK or autophagy with pharmacological inhibitors could alleviate the inflammation. Additionally, cell model showed that the mRNA expression of classic inflammatory factors (Il-1β, Il-6), macrophage polarization markers (iNOS, Arg1) and ROS production was significantly down-regulated after employing CSE specific inhibitor PAG. And PAG is capable of inhibiting excessive autophagy through the LKB1-AMPK-ULK1 axis. Interestingly, exogenous H2S could suppress inflammation response. Our study emphasizes the importance of CSE in regulating the macrophage-mediated response to E. coli. Increased CSE in macrophages leads to excessive inflammation, which should be considered a new target for drug development to treat intestinal infection.
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BIORESOURCE TECHNOLOGY
·
2022
·
IF 11.889
Lian Wang,Ning Li,Shiqin Yu,Jingwen Zhou
Caffeic acid is a phenylpropanoid which is widely used in medical industry. Microbial fermentation provides a green strategy for producing caffeic acid. To improve the capacity for caffeic acid production in Escherichia coli , the competing pathways for l -tyrosine synthesis were knocked out. The biosynthesis pathway of the cofactor FAD and the expression of previously reported polyphenol transporters were enhanced to promote the production of caffeic acid. Transcriptomics analysis was conducted to mine potential transporters that could further enhance the titer of caffeic acid in engineered E. coli . Transcriptomics data of E. coli under caffeic acid and ferulic acid stress showed that 19 transporters were upregulated. Among them, overexpression of ycjP , which was previously identified as a sugar ABC transporter permease, improved the caffeic acid titer to 775.7 mg/L. The caffeic acid titer was further improved to 7922.0 mg/L in a 5-L fermenter, the highest titer achieved by microorganisms.
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mSystems
·
2022
·
IF 7.324
Zhe Zhao,Ying Xu,Bo Jiang,Qingsheng Qi,Ya-Jie Tang,Mo Xian,Jichao Wang,Guang Zhao
The two-component system CpxRA can sense environmental stresses and regulate transcription of a wide range of genes for the purpose of adaptation. Despite extensive research on this system, the identification of the CpxR regulon is not systematic or comprehensive. Herein, genome-wide screening was performed using a position-specific scoring matrix, resulting in the discovery of more than 10,000 putative CpxR binding sites, which provides an extensive and selective set of targets based on sequence. More than half of the candidate genes ultimately selected (73/97) were experimentally confirmed to be CpxR-regulated genes through experimental analysis. These genes are involved in various physiological functions, indicating that the CpxRA system regulates complex cellular processes. The study also found for the first time that the CpxR-regulated genes ydeE, xylE, alx, and galP contribute to Escherichia coli resistance to acid stress, whereas prlF, alx, casA, yacH, ydeE, sbmA, and ampH contribute to E. coli resistance to cationic antimicrobial peptide stress. Among these CpxR-regulated genes, ydeE and alx responded to both stressors. In a similar way, a cationic antimicrobial peptide is capable of directly activating the periplasmic domain of CpxA kinase in vitro, which is consistent with the CpxA response to acid stress. These results greatly expand our understanding of the CpxRA-dependent stress response network in E. coli.IMPORTANCE CpxRA system is found in many pathogens and plays an essential role in sensing environmental signals and transducing information inside cells for adaptation. It usually regulates expression of specific genes in response to different environmental stresses and is important for bacterial pathogenesis. However, systematically identifying CpxRA-regulated genes and elucidating the regulative role of CpxRA in bacteria responding to environmental stress remains challenging. This study discovered more than 10,000 putative CpxR binding sites based on sequence. This bioinformatics approach, combined with experimental assays, allowed the identification of many previously unknown CpxR-regulated genes. Among the novel 73 CpxRA-regulated genes identified in this study, the role of nine of them in contributing to E. coli resistance to acid or cationic antimicrobial peptide stress was studied. The potential correlation between these two environmental stress responses provides insight into the CpxRA-dependent stress response network. This also improves our understanding of environment-bacterium interaction and Gram-negative pathogenesis.
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Microbial Cell Factories
·
2022
·Vol. 21
·期 1
·1-15
·
IF 6.352
Zhang Zhen,Yu Zichen,Wang Jinduo,Yu Yifa,Li Lanxiao,Sun Pengjie,Fan Xiaoguang,Xu Qingyang
Background 5-hydroxytryptophan (5-HTP), the direct biosynthetic precursor of the neurotransmitter 5-hydroxytryptamine, has been shown to have unique efficacy in the treatment of a variety of disorders, including depression, insomnia, and chronic headaches, and is one of the most commercially valuable amino acid derivatives. However, microbial fermentation for 5-HTP production continues to face many challenges, including low titer/yield and the presence of the intermediate L-tryptophan (L-Trp), owing to the complexity and low activity of heterologous expression in prokaryotes. Therefore, there is a need to construct an efficient microbial cell factory for 5-HTP production.Results We describe the systematic modular engineering of wild-type Escherichia coli for the efficient fermentation of 5-HTP from glucose. First, a xylose-induced T7 RNA polymerase-PT7 promoter system was constructed to ensure the efficient expression of each key heterologous pathway in E. coli. Next, a new tryptophan hydroxylase mutant was used to construct an efficient tryptophan hydroxylation module, and the cofactor tetrahydrobiopterin synthesis and regeneration pathway was expressed in combination. The L-Trp synthesis module was constructed by modifying the key metabolic nodes of tryptophan biosynthesis, and the heterologous synthesis of 5-HTP was achieved. Finally, the NAD(P)H regeneration module was constructed by the moderate expression of the heterologous GDHesi pathway, which successfully reduced the surplus of the intermediate L-Trp. The final engineered strain HTP11 was able to produce 8.58 g/L 5-HTP in a 5-L bioreactor with a yield of 0.095 g/g glucose and a maximum real-time productivity of 0.48 g/L/h, the highest values reported by microbial fermentation.Conclusion In this study, we demonstrate the successful design of a cell factory for high-level 5-HTP production, combined with simple processes that have potential for use in industrial applications in the future. Thus, this study provides a reference for the production of high-value amino acid derivatives using a systematic modular engineering strategy and a basis for an efficient engineered strain development of 5-HTP high-value derivatives.
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2022
·Vol. 106
·期 17
·5771-5783
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IF 5.56
Li Yihao,Wang Huimin,Wu Pingxiao,Jiang Lu,Ahmed Zubair,Ruan Bo,Yang Shanshan
Abstract The emergence and spread of antibiotic resistance genes (ARGs) induced by the overuse of antibiotics has become a serious threat to public health. Heavy metals will bring longer-term selection pressure to ARGs when the concentration of their residues is higher than that of antibiotics in environmental media. To explore the potential roles of montmorillonite (Mt) in the emergence of ARGs under divalent cadmium ion (Cd 2+ ) stress, Escherichia coli ( E. coli ) was induced continuously for 15 days under Cd 2+ gradient concentrations (16, 32, 64, 96, and 128 μg∙mL −1 ) with and without Mt. Subsequently, antibiotic resistance testing, transcriptomics, transmission electron microscope, scanning electron microscopy, and Fourier transform infrared were conducted for analysis. The results of characterization analysis showed that Cd 2+ could enhance the expression of resistance genes such as penicillin, tetracycline, macrolactone, and chloramphenicol in E. coli . Moreover, compared with Cd 2+ , Mt-Cd could inhibit the promotion of these resistances by alleviating the expressions of genes involved in cell wall/membrane, protein synthesis, transport systems, signal transduction, and energy supply processes. Therefore, the study promoted the understanding of Cd 2+ in triggering bacterial antibiotic resistance and highlighted a novel theme of clay’s ability to mitigate ecological risk of antibiotic resistance caused by heavy metals. Key points • Montmorillonite (Mt) could inhibit the promotion of antibiotic resistances. • E. coli formed a unique resistance mechanism by interacting with Mt and Cd 2+ . • Mt stimulated cellular signal transduction, cellular component, and energy supply.
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Frontiers in Bioengineering and Biotechnology
·
2022
·
IF 6.064
Wang Jing,Chen Qiaoyu,Wang Xin,Chen Kequan,Ouyang Pingkai
D-1,2,4-Butanetriol (BT) has attracted much attention for its various applications in energetic materials and the pharmaceutical industry. Here, a synthetic pathway for the biosynthesis of BT from d-arabinose was constructed and optimized in Escherichia coli. First, E. coli Trans1-T1 was selected for the synthesis of BT. Considering the different performance of the enzymes from different organisms when expressed in E. coli, the synthetic pathway was optimized. After screening two d-arabinose dehydrogenases (ARAs), two d-arabinonate dehydratases (ADs), four 2-keto acid decarboxylases (ADXs), and three aldehyde reductases (ALRs), ADG from Burkholderia sp., AraD from Sulfolobus solfataricus, KivD from Lactococcus lactis IFPL730, and AdhP from E. coli were selected for the bio-production of BT. After 48 h of catalysis, 0.88 g/L BT was produced by the recombinant strain BT5. Once the enzymes were selected for the pathway, metabolic engineering strategy was conducted for further improvement. The final strain BT5ΔyiaEΔycdWΔyagE produced 1.13 g/L BT after catalyzing for 48 h. Finally, the fermentation conditions and characteristics of BT5ΔyiaEΔycdWΔyagE were also evaluated, and then 2.24 g/L BT was obtained after 48 h of catalysis under the optimized conditions. Our work was the first report on the biosynthesis of BT from d-arabinose which provided a potential for the large-scale production of d-glucose-based BT.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2021
·
IF 5.279
Feifei Hou,Dexin Feng,Mo Xian,Wei Huang
2-Acetamidophenol (AAP) is an aromatic product with promising activities in agricultural applications and medical research. At present, AAP is synthesized by chemical methods from nonrenewable fossil fuel resources, which cause environmental pollution and the reaction conditions are harsh. In this study, we constructed the artificial biosynthetic pathway of AAP with five different expressed proteins in Escherichia coli for the first time. By introducing the hydrogen peroxide degrading enzyme catalase and improving cell tolerance to toxic intermediates or products, the yield of AAP reached 33.54 mg/L using shaking-flask culture. The best-engineered strain could produce 568.57 mg/L AAP by fed-batch fermentation from glucose and precursor (2-aminophenol, 2-AP) addition. Furthermore, a one-pot whole-cell cascade biocatalytic pathway to AAP and analogues was developed and optimized. This method can efficiently produce 1.8 g/L AAP using the methyl anthranilate hydrolysis product as the substrate. This study provides not only the de novo artificial biosynthetic pathway of AAP in E. coli but also a promising sustainable and efficient strategy to enable the synthesis of AAP on a gram scale.
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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
·
2023
·
IF 3.1
Liangwan Wei,Zhe Wang,Yindi Chu,Kun Cai,Wei Li,Piying Huang,Youcai Qin,Dailin Liu,Xiaocui Zhuang,Mingquan Guo,Xinbo Song,Enguo Fan
Antimicrobial resistance (AMR) crisis urges the development of new antibiotics. In the present work, we for the first time used bio-affinity ultrafiltration combined with HPLC-MS (UF-HPLC-MS) to examine the interaction between the outer membrane β-barrel proteins and natural products. Our results showed that natural product licochalcone A from licorice interacts with BamA and BamD with the enrichment factor of 6.38 ± 1.46 and 4.80 ± 1.23, respectively. The interaction was further confirmed by use of biacore analysis, which demonstrated that the Kd value between BamA/D and licochalcone was 6.63/28.27 μM, suggesting a good affinity. To examine the effect of licochalcone A on BamA/D function, the developed versatile in vitro reconstitution assay was used and the results showed that 128 μg/mL licochalcone A could reduce the outer membrane protein A integration efficiency to 20%. Although licochalcone A alone can not inhibit the growth of E. coli , but it can affect the membrane permeability , suggesting that licochalcone A holds the potential to be used as a sensitizer to combat AMR.
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JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2023
·Vol. 98
·期 10
·2597-2609
·
IF 3.4
Jun Chen,Xiaohong Yang,Shangqing Xia,Xue Li,Yutong Wang,Zongsheng Zhan,Mingxia Du,Dongliang Shao
BACKGROUND Persulfate (PS) has the capability to yield free radicals via activators, thereby shaping an advanced oxidation process that can significantly contribute to effective sterilization. Central to this technology is the pursuit of appropriate activators. RESULTS In our research, we successfully synthesized an economical and efficient PS activator, namely a pyrrhotite-loaded sludge carbon (Pyr-SC) composite. This was achieved via a straightforward procedure utilizing two environmentally friendly and cost-efficient raw materials: pyrite and sludge. Pyr-SC exhibited a specific surface area of 60.4 m 2 g −1 and rich functional groups such as carbon–sulfur and sulfur–oxygen. The magnetic and graphitic carbon structures were formed at high temperatures during the preparation process, and the sludge carbon (SC) exhibited porous defects, which allowed the effective insertion of iron/sulfur into SC to form the stable Pyr-SC structure. Pyr-SC activated PS, which further sterilized Escherichia coli in the wastewater at a sterilization rate of 7.00 lg E. coli at 10 7 cfu mL −1 in 80 min. The sterilization rate was less affected by temperature and pH. We verified sulfate, hydroxyl and oxygen free radicals produced by the Pyr-SC-activated PS. The Pyr-SC composite, thanks to its expedited electron transfer, could activate PS to engender free radicals. Furthermore, the oscillatory transformation of iron ions caused by the monosulfide ion on the Pyr-SC surface augmented the production of free radicals. An assessment of Pyr-SC's stability was conducted, adhering to the principles of magnetic separation. After five cycles in the Pyr-SC/PS reaction system, the sterilization rate reached 3.29 lg, whereas the leaching rate of iron in Pyr-SC decreased. The Pyr-SC/PS reaction system also had a broad spectrum of wastewater. CONCLUSION The economically prepared Pyr-SC composite provided an effective technology for activating PS and sterilizing microorganisms in wastewater. © 2023 Society of Chemical Industry.
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Bioresources and Bioprocessing
·
2021
·Vol. 8
·期 1
·1-16
·
IF 4.578
Ding Qiang,Liu Yadi,Hu Guipeng,Guo Liang,Gao Cong,Chen Xiulai,Chen Wei,Chen Jian,Liu Liming
Microbial organelles are a promising model to promote cellular functions for the production of high-value chemicals. However, the concentrations of enzymes and nanoparticles are limited by the contact surface in single Escherichia coli cells. Herein, the definition of contact surface is to improve the amylase and CdS nanoparticles concentration for enhancing the substrate starch and cofactor NADH utilization. In this study, two biofilm-based strategies were developed to improve the contact surface for the production of shikimate and L-malate. First, the contact surface of E. coli was improved by amylase self-assembly with a blue light-inducible biofilm-based SpyTag/SpyCatcher system. This system increased the glucose concentration by 20.7% and the starch-based shikimate titer to 50.96 g L−1, which showed the highest titer with starch as substrate. Then, the contact surface of E. coli was improved using a biofilm-based CdS-biohybrid system by light-driven system, which improved the NADH concentration by 83.3% and increased the NADH-dependent L-malate titer to 45.93 g L−1. Thus, the biofilm-based strategies can regulate cellular functions to increase the efficiency of microbial cell factories based on the optogenetics, light-driven, and metabolic engineering.
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Frontiers in Bioengineering and Biotechnology
·
2021
·
IF 5.89
Li Bingyu,Hou Chaofan,Ju Xian,Feng Yong,Ye Zhi-Qiang,Xiao Yunzhu,Gu Mingyao,Fu Chunxiang,Wei Chaoliang,You Conghui
Motility is finely regulated and is crucial to bacterial processes including colonization and biofilm formation. There is a trade-off between motility and growth in bacteria with molecular mechanisms not fully understood. Hypermotile Escherichia coli could be isolated by evolving non-motile cells on soft agar plates. Most of the isolates carried mutations located upstream of the flhDC promoter region, which upregulate the transcriptional expression of the master regulator of the flagellum biosynthesis, FlhDC. Here, we identified that spontaneous mutations in clpX boosted the motility of E. coli largely, inducing several folds of changes in swimming speed. Among the mutations identified, we further elucidated the molecular mechanism underlying the ClpXV78F mutation on the regulation of E. coli motility. We found that the V78F mutation affected ATP binding to ClpX, resulting in the inability of the mutated ClpXP protease to degrade FlhD as indicated by both structure modeling and in vitro protein degradation assays. Moreover, our proteomic data indicated that the ClpXV78F mutation elevated the stability of known ClpXP targets to various degrees with FlhD as one of the most affected. In addition, the specific tag at the C-terminus of FlhD being recognized for ClpXP degradation was identified. Finally, our transcriptome data characterized that the enhanced expression of the motility genes in the ClpXV78F mutations was intrinsically accompanied by the reduced expression of stress resistance genes relating to the reduced fitness of the hypermotile strains. A similar pattern was observed for previously isolated hypermotile E. coli strains showing high expression of flhDC at the transcriptional level. Hence, clpX appears to be a hot locus comparable to the upstream of the flhDC promoter region evolved to boost bacterial motility, and our finding provides insight into the reduced fitness of the hypermotile bacteria.
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