Food Bioscience
·
2025
·
IF 5.9
Hongyang Chen,Zimao Ye,Yanchi Liu,Zhiqin Zhou
An integrated physiological and non-targeted metabolomics approach was used to construct a eugenol-based polymethoxyflavones nanoemulsion delivery system and examine its increased antibacterial activity on E. coli . Compared with pure eugenol nanoemulsion (EG, MIC: 640 μg/mL), the polymethoxyflavones-eugenol nanoemulsion (EGP) exhibited significantly enhanced antimicrobial activity (MIC: 320 μg/mL). EGP treatment disrupted the integrity of E. coli cell membranes and walls, increased cell permeability. Non-targeted metabolomics analysis (compared with CK) revealed 685 upregulated and 642 downregulated differentially accumulating metabolites, lysine and glutamine are reduced in E. coli , and glutaric acid, aminoadipic acid, and D-lactic acid are increased. Pathway enrichment analysis showed that amino acid metabolism and energy metabolism were significantly disturbed by TCA cycle disruption. EGP exhibits superior antimicrobial efficacy against E. coli through a multi-targeted mechanism involving cell membrane disruption and metabolic pathway interference. This study provides valuable insights into the development of natural antimicrobial nanoemulsion as potential alternatives to synthetic preservatives for food safety applications.
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ARCHIVES OF MICROBIOLOGY
·
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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Communications Biology
·
2020
·Vol. 3
·期 1
·1-10
·
IF 4.165
Liu Yuan,Jia Yuqian,Yang Kangni,Li Ruichao,Xiao Xia,Wang Zhiqiang
Recent emergence of high-level tigecycline resistance mediated by Tet(X3/X4) in Enterobacteriaceae undoubtably constitutes a serious threat for public health worldwide. Antibiotic adjuvant strategy makes antibiotic more effective against these resistant pathogens through interfering intrinsic resistance mechanisms or enhancing antibiotic actions. Herein, we screened a collection of drugs to identify compounds that are able to restore tigecycline activity against resistant pathogens. Encouragingly, we discovered that anti-HIV agent azidothymidine dramatically potentiates tigecycline activity against clinically resistant bacteria. Meanwhile, addition of azidothymidine prevents the evolution of tigecycline resistance in E. coli and the naturally occurring horizontal transfer of tet (X4). Evidence demonstrated that azidothymidine specifically inhibits DNA synthesis and suppresses resistance enzyme activity. Moreover, in in vivo infection models by Tet(X4)-expression E. coli , the combination of azidothymidine and tigecycline achieved remarkable treatment benefits including increased survival and decreased bacterial burden. These findings provide an effective regimen to treat infections caused by tigecycline-resistant Escherichia coli .
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ACS Synthetic Biology
·
2020
·
IF 4.411
Tao Zhan,Qian Chen,Chao Zhang,Changhao Bi,Xueli Zhang
Glycolate is an important α-hydroxy acid with a wide range of industrial applications. The current industrial production of glycolate mainly depends on chemical synthesis, but biochemical production from renewable resources using engineered microorganisms is increasingly viewed as an attractive alternative. Crude glycerol is an abundant byproduct of biodiesel production and a widely investigated potential sustainable feedstock. Here, we constructed a novel biosynthetic pathway for the production of glycolate from glycerol in Escherichia coli. The pathway starts from the oxidation of glycerol to d-glycerate by alditol oxidase, followed by sequential enzymatic dehydrogenation and decarboxylation as well as reduction reactions. We screened and characterized the catalytic activity of candidate enzymes, and a variant of alditol oxidase from Streptomyces coelicolor A3(2), 2-hydroxyglutarate-pyruvate transhydrogenase from Saccharomyces cerevisiae, α-ketoisovalerate decarboxylase from Lactococcus lactis, and aldehyde dehydrogenase from Escherichia coli were selected and assembled to create an artificial operon for the biosynthetic production of glycolate from glycerol. We also characterized the native strong constitutive promoter Plpp from E. coli and compared it with the PT7 promoter, which was employed to express the artificial operon on the plasmid pSC105-ADKA. To redirect glycerol flux toward glycolate synthesis, we deleted key genes of the native glycerol assimilation pathways and other branches of native E. coli metabolism, and we introduced a second plasmid expressing Dld3 to reduce the accumulation of the intermediate d-glycerate. Finally, the engineered strain TZ-108 harboring pSC105-ADKA and pACYC184-Plpp-Dld3 produced 0.64 g/L glycolate in shake flasks, which was increased to 4.74 g/L in fed-batch fermentation. This study provides an alternative pathway for glycolate synthesis and demonstrates the potential for producing other commodity chemicals by redesigning glycerol metabolism.
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Frontiers in Bioengineering and Biotechnology
·
2021
·
IF 5.89
E Yang,Meng Jun,Cai Heqing,Li Caibin,Liu Sainan,Sun Luming,Liu Yanxiang
The organic compounds from biochar play a role of hormone analogs, stimulating the expression of metabolites by controlling related gene and protein. In this experiment, we reported the L-histidine biosysthesis was promoted by biochar treatment in E. coli unlike genetic engineering of the traditional method. The related results indicated the most optimal concentration was found to be 3%, and 7% is the lethal dose. E. coli was inhibited in the high-concentration treatment. On the other hand, docking technology was usually used as drug screening, basing on Lock-and-key model of protein in order to better understand mechanisms. So the organic compounds of biochar from GC-MS analysis that acted as ligands were connected to HisG protein controlling L-histidine biosysthesis in E. coli. The result showed that the three organic molecules interacted with HisG protein by hydrogen bond. So we considered that these three compounds play regulatory roles in L-histidine biosysthesis, and the hisG gene expression fully supports this conclusion.
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PROTEIN EXPRESSION AND PURIFICATION
·
2015
·
IF 1.695
Fanqiang Meng,Haizhen Zhao,Chong Zhang,Fengxia Lu,Xiaomei Bie,Zhaoxin Lu
A potential bacteriocin gene was isolated from 18575 ORFs by bioinformatics methods. It was named pln1 , and cloned into pET32a. Then, it was expressed as a thioredoxin-Pln1 fusion protein in Escherichia coli BL21 (DE3). The fusion protein was purified by Ni-NTA, and thioredoxin was removed by enterokinase. Finally, Pln1 was purified using a cation affinity column. The yields of fused and cleaved Pln1 peptides were 100–110 mg/l and 9–11 mg/l, respectively. Pln1 was stable in an acidic environment and at temperatures below 60 °C, but was easily degraded under alkaline conditions and by protease treatment. The cleaved and purified Pln1 showed strong antimicrobial activity against gram-positive bacteria such as Micrococcus luteus CMCC 63202, Staphylococcus epidermidis , Lactococcus lactis NZ3900, Lactobacillus paracasei CICC 20241, and Listeria innocua CICC 10417. In particular, Pln1 had a better activity against methicillin-resistant S. epidermidis (MRSE) than nisin, thereby offering an attractive approach to counter bacterial antibiotic resistance .
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BIOCHEMICAL ENGINEERING JOURNAL
·
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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ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY
·
2015
·
IF 2.084
Mengnan Qin,Zhifen Lin,Dali Wang,Xi Long,Min Zheng,Yanling Qiu
Bacteria in the environment face the threat of antibiotics. However, most studies investigating the toxicity and toxicity mechanisms of antibiotics have been conducted on microorganisms in aerobic conditions, while studies examining the anaerobic toxicity and toxicity mechanisms of antibiotics are still limited. In this study, we determined the aerobic and anaerobic toxicities of sulfonamides (SAs) on Escherichia coli . Next, a comparison of the aerobic and anaerobic toxicities indicated that the SAs could be divided into three groups: Group I: log(1/EC 50-anaerobic ) > log(1/EC 50-aerobic ) (EC 50-anaerobic /EC 50-aerobic , the median effective concentration under anaerobic/aerobic conditions), Group II: log(1/EC 50-anaerobic ) ≈ log(1/EC 50-aerobic ), and Group III: log(1/EC 50-anaerobic ) < log(1/EC 50-aerobic ). Furthermore, this division was not based on the reactive oxygen species (ROS) level or the interaction energy ( E binding ) value, which represents the affinity between SAs and dihydropteroate synthase (dhps) but rather on the total binding energy. Furthermore, SAs with greatly similar structures were categorized into different groups. This deep insight into the difference between aerobic and anaerobic toxicities will benefit environmental science, and the results of this study will serve as a reference for the risk assessment of chemicals in the environment.
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ULTRASONICS SONOCHEMISTRY
·
2020
·
IF 6.513
Mingming Guo,Lianjiao Zhang,Qiao He,Saifanassour Ali Arabi,Huanhuan Zhao,Weijun Chen,Xingqian Ye,Donghong Liu
Essential oil nanoemulsions have been proven to have stronger antimicrobial effects compared to the essential oil alone or coarse emulsion. Sonoporation could be the promising candidate to trigger a synergistic effect with thyme essential oil nanoemulsion (TEON) and produce a more effective antibacterial efficacy. Therefore, in this study, the bactericidal effects of ultrasound (US) in combination with TEON treatments against Escherichia coli ( E. coli ) O157:H7 were investigated. The remarkable synergistic effects of US (20 kHz, 255 W/cm 2 , 9 min) and TEON (0.375 mg/mL) treatments at 22 °C reduced E. coli O157:H7 populations by 7.42 ± 0.27 log CFU/mL. The morphological changes of cells exposed to different treatments were observed by scanning electron microscopy and transmission electron microscopy. The results showed that the synergistic effects of the ultrasound and TEON treatments altered the morphology and interior microstructure of organism cells. Laser scanning confocal microscopy (LSCM) images revealed that the combination treatments of ultrasound and TEON altered the permeability of cell membranes, and this affected the integrity of E. coli O157:H7 cells. This was further indicated by the high amounts of nucleic acids and proteins released from these cells following treatment. The results from this study illustrated the mechanisms of the synergistic effects of sonoporation and TEON treatments and provided valuable information for their potential in food pasteurization.
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Nanomedicine
·
2018
·
IF 5.005
Yahui Zhang,Lin Wang,Xiang Xu,Fang Li,Qingsheng Wu
Aim: The combined efficacy of CuO nanoparticles (NPs) with 22 kinds of antibiotics against Escherichia coli was systematic studied, and CuO with cephalexin synergistic system was screened out. Methods: Antimicrobial susceptibility test included disk diffusion test, checkerboard method and time-kill assay. The interactions of CuO NPs and antibiotics were analyzed by x-ray photoelectron spectroscopy, Fourier transform infrared spectra and Zeta. The interactions between bacteria and antibacterial agents were studied by surface plasmon resonance sensor for the first time. Results & Conclusion: Synergistic effect (1+1>2) was observed when CuO NPs combined with cephalexin against E. coli. The concentrated cephalexin molecules interacted more strongly with the E. coli cells to make cell wall become loose. Then, CuO NPs were more easily to damage and penetrate cells. Besides, the presence of antibiotics did not enhance Cu2+ release, Cu2+ uptake and reactive oxygen species generation. But the presence of cephalexin greatly enhanced cell permeability in comparison to others.
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JOURNAL OF MICROBIOLOGY AND BIOTECHNOLOGY
·
2025
·
IF 3.1
Kaize Kong,Feitao Chen,Huan Fang,Pingtao Jiang,Xinfang Zhao,Jijiao Zhang,Huina Dong,Hongxing Jin,Dawei Zhang
Isopropyl β-D-thiogalactopyranoside (IPTG), while widely utilized for inducing gene expression in systems governed by T7 lac and related promoters, poses significant challenges due to its toxicity and expense, prompting the exploration of alternative induction strategies. In this study, we developed a series of inducer-free vitamin B 12 -producing strains featuring thermally regulated pathway genes. We engineered a thermal switch by replacing the lacI promoter with the P R promoter, which is regulated by the temperature-sensitive repressor cI857 from the λ bacteriophage. As a result, target genes driven by T7 lac or other lac -derived promoters containing lac operators were expressed upon lowering the temperature. Our findings indicate that culturing at 37°C and then shifting to 32°C when the optical density at 600 nm reaches 2 is the most effective strategy for vitamin B 12 production. Additionally, the vitamin B12 titer increased by 37.96% after introducing an ssrA degradation tag at the C-terminus of lacI . This study introduces a novel strategy for vitamin B 12 production that circumvents the need for IPTG by implementing a thermal switch. This approach may have significant implications for chemical bioproduction processes that have traditionally relied on IPTG for gene induction.
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Yongli Zhang,Zhao Zhou,Jun Wu,Yiyang Shi,Xinxiao Sun,Jia Wang,Xiaolin Shen,Qipeng Yuan
Methylation reactions are involved in the synthesis of various natural molecules, but the limited supply of intracellular S-adenosylmethionine (SAM) poses a challenge for the large-scale microbial production of methylated compounds. In this study, we conducted a comprehensive analysis and optimization of the SAM cycle regeneration pathway, enhancing the methylation efficiency in three key steps of the pathway (SAM carbon skeleton cycle, 5-methyltetrahydrofolate cycle, and adenine-ATP cycle), and constructed an efficient endogenous methylation platform in E. coli . This platform significantly increased the intracellular level of the cofactor SAM and improved methylation efficiency. Using this platform, the production of methylated products, including ferulic acid, vanillyl alcohol, and melatonin, increased by 4.2-fold, 1.28-fold, and 44.6 %, respectively. Notably, the ferulic acid titer reached 7.24 g/L, marking the highest level reported to date. These findings demonstrate the broad applicability of this methylation platform, providing a generalizable and effective approach for the biosynthesis of a wide range of SAM-dependent products.
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