INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
·
2016
·Vol. 51
·期 10
·2178-2184
·
IF 1.504
Yuanlong Chi,Qisheng Zhang,Gong Chen,Jiayuan Zhao,Hongmei Zhang,Dongying Jia,Kai Yao
Summary Starter cultures of low-salt Chinese paocai were screened from 135 lactic acid bacteria (LAB) by evaluating their antimicrobial activity and growth characteristics. Furthermore, the survival of Escherichia coli O157:H7, nitrite contents and sensory acceptability of the starter-fermented paocai were evaluated. LAB BC92, which was identified as Lactobacillus pentosus , was used as a starter culture to produce paocai. In comparison with naturally fermented paocai, the disappearance time of E. coli O157:H7 in starter-fermented paocai decreased from 5.29 to 3.82 days, and the maximum nitrite content decreased from 11.73 to 8.64 mg kg −1 , and the nitrite reduction time decreased from 4 to 3 days. In addition, starter fermentations were able to accelerate the flavour formation and shorten the paocai ripening period. The paocai that was fermented naturally and fermented by BC92 all had good sensory acceptance, and no significant difference ( P > 0.05) was observed.
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Environmental Technology & Innovation
·
2024
·
IF 6.7
Guoming Zeng,Yu He,Xuanhao Fan,Xiaoling Lei,Quanfeng Wang,Haoxuan Wei,Da Sun
Surface modification can significantly improve nano zero-valent iron (nZVI) stability. However, different methods and materials significantly affect nZVI toxicity, and the effects on bacterial metabolic processes and corresponding molecular mechanisms require further study. In this study, Chlorella biochar-loaded nano zero-valent iron (nZVI/BC) was prepared, showing optimum removal of Microcystis aeruginosa ( M. aeruginosa ) at a dosing rate of 12.5 g L −1 . The toxicity against Escherichia coli ( E. coli ) was investigated, revealing time-dependent inactivation efficiency, achieving −3.60 log at 30 min and −5.0 log for a single nZVI. Transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) analyses revealed that nZVI exhibited stronger adsorption to cells compared to nZVI/BC, with both nZVI and nZVI/BC primarily interacting with amine, carboxyl, and ester groups on the cell surface. Physiological, biochemical, ROS quenching, and metabolomics experiments indicated that ROS played a key role in the inactivation of E. coli . This study proposes a strategy to balance the stability of nZVI with its biocompatibility.
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AFRICAN JOURNAL OF BIOTECHNOLOGY
·
2017
·Vol. 16
·期 50
·2307-2316
·
IF 0
Haiyuan Liu,Shu Han,Liping Xie,Jie Pan,Wei Zhang,Guihua Gong,Youjia Hu
2-C-Methyl-D-erythritol-4-phosphate (MEP) pathway has been extensively employed for terpenoids biosynthesis in Escherichia coli. In this study, to obtain key-enzymes of MEP pathway for squalene production, overexpression of different combination of MEP pathway genes were compared. Squalene production in strain YSS12 with overexpressed dxs, idi and ispA of MEP pathway from E. coli was improved by 71-fold when compared with strain YSS3 which only contained double copy SQS. Analysis of transcriptional levels of MEP pathway genes in engineering strains showed that different squalene production can be attributed to changed transcriptional levels of co-overexpressed genes dxs, idi, ispG and ispA in engineering strains. Furthermore, different E. coli expression hosts were compared for squalene production, among which BL21(DE3) was the best squalene producer. These results illustrate that dxs, idi and ispA of the MEP pathway from E. coli were key-enzymes for squalene production in E. coli. These key-enzymes of MEP pathway could also be applied to other terpenoids production in E. coli.
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PubMed
Food Bioscience
·
2024
·
IF 4.8
Jinyue Sun,Han-Xiao Zhuang,Jia-Neng Pan,Qian-Jun Shen,Hui-Ling Shen,Wen-Wen Zhou
This study has investigated cuproptosis caused by copper sulfate (CuSO 4 ) in Escherichia coli O157: H7 and its mechanism. Meanwhile, the mechanism of CuSO 4 combined with natamycin (Nata) against E. coli O157: H7 planktonic and biofilm cells were also investigated. Finally, we prepared an agar-based film, researched its properties, and used it for packaging cherry tomatoes and purple kale. The results indicated that CuSO 4 could cause cuproptosis in E. coli O157: H7 and lead the genes related to Fe-S cluster protein ( hyfA , sufB , xdhC , and narY ) to down-regulate and cuproptosis-related proteins to change. Then, CuSO 4 combined with Nata could synergistically decrease E. coli O157: H7 bacterial counts in planktonic condition and biofilm by synergistically affecting the membrane potential, cytoplasm leakage, permeability of outer membrane and inner membrane. After that, CuSO 4 and Nata could change the mechanical properties, color and optical characteristics of agar-based film, and decrease the water vapor permeability and oxygen permeability value. Finally, CuSO 4 @Nata@Carboxymethylcellulose@Agar film effectively lowered the counts of E. coli O157: H7 in cherry tomatoes and purple kale during the storage.
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INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
·
2025
·
IF 5.2
Kai Fan,Lijing Li,Jiaxin Wu
Escherichia coli ( E. coli ) O157:H7 on the surfaces of fruits and vegetables poses significant risks to human health. This study assessed the bactericidal mechanisms of ultrasound (US) and oregano essential oil nanoemulsion (OEON) against E. coli , as well as their application in storage preservation of cherry tomatoes. The results showed that US + OEON treatment exhibited markedly superior inactivation effect on E. coli compared to their individual treatments. OEON (2 %) combined with ultrasonic treatment (375 W) for 4 min reduced the viable E. coli count by 5.06 ± 0.22 log CFU/mL. This performance markedly exceeded that of single treatments, with US achieving 1.15 ± 0.10 log CFU/mL reduction and OEON 1.04 ± 0.18 log CFU/mL reduction. The synergistic treatment intensified lipid peroxidation of bacterial cell membranes and enhanced membrane permeability. Furthermore, in preservation applications on cherry tomatoes, US + OEON effectively suppressed total viable counts, achieving a 1.44 ± 0.19 log CFU/mL reduction after 4-min treatment with 2 % OEON combined with 375 W US. This approach induced no adverse effects on cherry tomato color, texture, nutritional composition, or antioxidant properties. In summary, compared to US or OEON treatment alone, US + OEON treatment exhibits superior antibacterial effect and improves the storage quality of cherry tomatoes.
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PubMed
高影响因子
FOOD CHEMISTRY
·
2020
·
IF 6.306
Miaolin Duan,Xiaoyue Xiao,Yanmei Huang,Guoqiang Li,Shan Shan,Xi Lv,Houde Zhou,Silu Peng,Chengwei Liu,Daofeng Liu,Weihua Lai
Escherichia coli O157:H7 makes a major threat to human health. Aiming to detect Escherichia coli O157:H7 sensitively, hybridization chain reaction signal amplified immunoassay (immuno-HCR) based on contact quenching (CQ) and fluorescence resonance energy transfer (FRET) was developed. The background of the new designed HCR hairpins (CQ-FRET hairpins) was reduced by contact-quenching fluorescein (FAM) and breaking FRET from donor (FAM) to acceptor (Cy5). The F/F 0 ratio of CQ-FRET hairpins (37.02) was obviously higher than that of two other common HCR fluorescent hairpins (CQ hairpins, 21.45; FRET hairpins, 4.61). The limit of detection of the assay was 3.5 × 10 1 CFU/mL and obviously lower than that of CQ hairpins based immuno-HCR (3.28 × 10 3 CFU/mL) and FRET hairpins based immuno-HCR (6.49 × 10 4 CFU/mL). The proposed low fluorescent background immuno-HCR with high sensitivity which was verified in contaminated milk samples could be potentially used in the detection of various pathogens.
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PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Aiyun Guo,Qixing Zhou,Yanyu Bao,Fanghan Qian,Xu Zhou
Conjugative plasmid transfer is a major contributor to the spread of antibiotic resistance genes (ARGs). However, the role of conventional fungicides on conjugative plasmid transfer has been neglected. Based on the condition that the increasing use of the combination of nano- and conventional fungicides will lead to combined contamination, the effects of a conventional fungicide prochloraz alone or in combination with nano-CuO on the conjugation of plasmid RP4 between Escherichia coli in phosphate-buffered saline were investigated in this study. The results demonstrated that 50 µg/L prochloraz alone significantly increased the conjugative transfer by 1.82 folds. The combination of 100 µg/L nano-CuO and prochloraz at 5, 50, and 500 µg/L significantly increased the conjugation by 2.56, 3.61, and 2.13 folds, respectively. The promotion of conjugative transfer of ARGs mediated by fungicides is mainly attributed to (i) the increased cell membrane permeability, (ii) the increased cell adhesion via enhancing the synthesis of polysaccharides in extracellular polymeric substances, and (iii) the up-regulation of the genes relevant to conjugation, oxidative stress, SOS response, outer membrane, polysaccharide export, intercellular adhesion, and ATP synthesis. Our findings provide evidence for the contribution of fungicides to ARGs transfer, which is significant to control the risk of ARGs dissemination.
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PubMed
高影响因子
INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
·
2025
·
IF 5.2
Dan Liu,Yaokun Pang,Shenrui Pan,Jianxia Sun
More attention has been paid to developing new antibacterial drugs from natural products due to antibacterial resistance. Ferulic acid (FA) is a natural phenolic acid with demonstrated antimicrobial effects. However, its bactericidal activity is insufficient to achieve a rapid bacteria reduction in a short time. This study demonstrates the antimicrobial activity and synergistic interaction of FA in combination with ultraviolet A (UV-A) against Escherichia coli (E. coli) . The synergistic activity against E. coli was concentration and time-dependent. A set of associated changes in cellular functions of E. coli including membrane integrity, cell membrane permeability and DNA damages were measured. Morphologically, the treated cells exhibited a bacterial membrane and DNA dysfunction. Furthermore, the photostability and photochemical pathway of FA upon UV-A exposure was investigated. A rapid photochemical degradation of FA upon UV-A irradiation was observed due to the photoisomerization process of FA. Type II reaction was assumed as the main photochemical pathway as evidenced by the actions of different quenching agents. Antibacterial activity of FA + UV-A was also tested on chicken breast meat. A reduction of the loads of E. coli bacteria on chicken and good maintenance of its quality was achieved. This combination of methods helps to reduce the use of chemical food preservatives and provide new ways to control pathogenic microorganisms in food industry.
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PubMed
高影响因子
ENZYME AND MICROBIAL TECHNOLOGY
·
2023
·
IF 3.4
Rui Huang,Chuang Li,Shi-Guang Zhao,Qing-Tao Liu,Yan Liu,Zheng-Lian Xue
In order to excavate microbial epoxide hydrolases (EHs) with desired catalytic properties, a novel EH, Sf EH1, was identified based on the genome annotation of Streptomyces fradiae and sequence alignment analysis with local protein library. The Sf EH1-encoding gene, sfeh 1, was then cloned and over-expressed in soluble form in Escherichia coli /BL21(DE3). The optimal temperature and pH of recombinant Sf EH1 (re Sf EH1) and re Sf EH1-expressing E. coli ( E. coli / sfeh 1) were both determined as 30 ℃ and 7.0, also indicating that the influences of temperature and pH on re Sf EH1′s activities were more obvious than those of E. coli / sfeh 1 whole cells. Subsequently, using E. coli / sfeh 1 as catalyst, its catalytic properties towards thirteen common mono-substituted epoxides were tested, in which E. coli / sfeh 1 had the highest activity of 28.5 U/g dry cells for rac -1,2-epoxyoctane ( rac - 6a ), and ( R )-1,2-pentanediol (( R )- 3b ) (or ( R )-1,2-hexanediol (( R )- 4b )) with up to 92.5% (or 94.1%) ee p was obtained at almost 100% conversion ratio. Regioselectivity coefficients (α S and β R ) displayed in the enantioconvergent hydrolysis of rac - 3a (or rac - 4a ) were calculated to be 98.7% and 93.8% (or 95.2% and 98.9%). Finally, the reason of the high and complementary regioselectivity was confirmed by both kinetic parameter analysis and molecular docking simulations .
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高影响因子
PROCESS BIOCHEMISTRY
·
2018
·
IF 2.616
Liqing Zhao,Yingmiao Xie,Liuyan Chen,Xuefeng Xu,Cindy Xinxin Zhao,Feng Cheng
Biotransformation of isoeugenol to vanillin is an attractive approach in industry for vanillin synthesis. However, the biotransformation efficiency is hampered by the low activity of isoeugenol monooxygenase (IEM) and the product inhibition towards IEM. Therefore, it is worth discovering a new IEM and improving its enzymatic properties by protein engineering. Herein, a new IEM720 gene was firstly cloned from microbial metagenome and successfully expressed in E. coli . Secondly, five potentially beneficial amino acid positions were selected by a “three-criteria” in silico system and visual inspection was performed for grouping them into two sets (regions A and B). The variant IEM720-F281Q displayed highest isoeugenol conversion and k cat value after screening the site-saturation libraries of these five positions. Furthermore, the structure-functional relationships of the beneficial substitution on IEM activity were investigated. The final vanillin concentration reached ∼4.5 g/L (∼75% conversion) by combining sol-gel chitosan membrane (for relieve of product inhibition) and E. coli cells harboring IEM720-F281Q.
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高影响因子
APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2021
·Vol. 193
·期 7
·2029-2042
·
IF 2.926
Xu Jian-Miao,Cao Hui-Ting,Wang Ming,Ma Bao-Jian,Wang Liu-Yu,Zhang Kai,Cheng Feng,Xue Ya-Ping,Zheng Yu-Guo
d -amino acid oxidase (DAAO) is widely used in the industrial preparation of l -amino acids, and cultivating Escherichia coli ( E. coli ) expressing DAAO for the biosynthesis of l -phosphinothricin ( l -PPT) is very attractive. At present, the biomass production of DAAO by fermentation is still limited in large-scale industrial applications because the expression of DAAO during the fermentation process inhibits the growth of host cells, which limits higher cell density. In this study, the factors that inhibit the growth of bacterial cells during a 5-L fed-batch fermentation process were explored, and the fermentation process was optimized by co-expressing catalase (CAT), by balancing the biomass and the enzyme activity, and by adding exogenous d -alanine ( d -Ala) to relieve the limitation of DAAO on the cells and optimize fermentation. Under optimal conditions, the DO-STAT feeding mode with DO controlled at 30% ± 5% and the addition of 27.5 g/L lactose mixed with 2 g/L d -Ala during induction at 28 °C resulted in the production of 26.03 g dry cell weight (DCW)/L biomass and 390.0 U/g DCW specific activity of DAAO; an increase of 78% and 84%, respectively, compared with the initial fermentation conditions. The fermentation strategy was successfully scale-up to a 5000-L fermenter.
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PubMed
高影响因子
Catalysts
·
2021
·Vol. 11
·期 2
·184
·
IF 4.146
Huang Zhou,Fengjiao He
β-NaYF4:Yb,Er,Gd fluorescent nanorods were successfully coupled to a reduced TiO2(UCNPs@R-TiO2) nanocomposite and applied to visible-light catalytic sterilization under 980 nm near-infrared (NIR) light illumination. The UCNPs (β-NaYF4:Yb,Er,Gd) absorb the NIR light and emit red and green light. The visible light can be absorbed by the R-TiO2(Eg = 2.8 eV) for the photocatalytic reaction. About 98.1% ofEscherichia coliwere effectively killed upon 12 min of NIR light irradiation at a minimum inhibitory concentration (MIC) of 40 μg/mL UCNPs@R-TiO2nanocomposite. The bactericidal properties were further evaluated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. We found that the high bactericidal activity was due to the synergistic effect between the UCNPs and R-TiO2. Moreover, the UCNPs show excellent upconversion luminance properties, and the introduction of visible-light-absorbed R-TiO2nanoparticles (2.8 eV) was conducive to the efficient separation and utilization of photogenerated electron-hole pairs.
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危险品化学品经营许可证（带存储）