3 Biotech
·
2020
·Vol. 10
·期 12
·1-9
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IF 1.798
Zhang Jun,Tian Miao,Lv Pengmei,Luo Wen,Wang Zhiyuan,Xu Jingliang,Wang Zhongming
Long-chain fatty acids are widely used in food and chemical industries, and the enzymatic preparation of fatty acids is considered an environmentally friendly process. In the present study, long-chain fatty acids were prepared by the enzymatic hydrolysis of rapeseed oil with a genetically engineered lipase. Because thermophilic lipase has strong stability at higher temperatures, it was more suitable for the industrial production of long-chain fatty acids. Therefore, the thermophilic lipase BTL2 from Geobacillus thermocatenulatus was efficiently expressed in E. coli BL21(DE3) cells with an enzyme activity of 39.50 U/mg followed by gene codon optimisation. Experimental results showed that the recombinant lipase BTL2 exhibited excellent resistance to certain organic solvents ( n -hexane, benzene, ethanol, and butanol). The metal cation Ca 2+ and the non-ionic surfactant Triton-100X enhanced enzyme activity by 7.36% and 56.21% respectively. Moreover, the acid value of the liberated long-chain fatty acids by hydrolysing rapeseed oil was approximately 161.64 mg KOH/g at 50 °C in 24 h, the hydrolytic conversion rate was 91.45%, and the productivity was approximately 6.735 mg KOH/g h. These results suggested that the recombinant lipase BTL2 has excellent hydrolytic performance for rapeseed oil and showed great potential for the enzymatic preparation of long-chain fatty acids.
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JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2020
·Vol. 95
·期 6
·1756-1772
·
IF 2.75
Guanshu Li,Yuejiao Cao,Ludong Yi,Jun Wang,Youtao Song
BACKGROUND The recovery and reuse of sonocatalysts are the pivotal issues in the sonocatalytic degradation of organic pollutants. The use of some natural minerals as the carrier is not only beneficial to recycling of sonocatalysts, but also reduces the treatment costs of organic pollutants. Two kinds of hydroxyapatite (HAP), Ox Bone (OB)-HAP and synthesized (Syn)-HAP combine with the Pt-TiO 2 /(Er 3+ :Y 3 Al 5 O 12 @Ta 2 O 5 ) (P-TET) composite, obtaining two Z-scheme sonocatalysts, P-TET/OB-HAP and P-TET/Syn-HAP, respectively. The sonocatalytic activities of the prepared samples are investigated via degradation of prometryn and disinfection of Escherichia coli . RESULTS A series of characterizations showed that the Z-scheme P-TET/(OB or Syn)-HAP sonocatalysts were prepared successfully. To evaluate their sonocatalytic activities, some influencing factors such as ultrasonic irradiation time, inorganic oxidants, used times and trapping agents on the sonocatalytic degradation prometryn were determined. The best degradation ratio (80.31% based on N computing and 85.07% based on S atom computing) of prometryn could be obtained for 10 mmol L −1 K 2 S 2 O 8 , 1.0 g L −1 P-TET/OB-HAP sonocatalyst and 150 min ultrasonic irradiation. The excellent sonocatalytic disinfection ratio (88.65%) of E. coli could also be obtained under 40 min ultrasound irradiation. Moreover, a possible mechanism on sonocatalytic degradation of prometryn was illustrated. CONCLUSION The treated bovine bone HAP was directly used as a carrier to combine with P-TET to construct a novel Z-scheme P-TET/OB-HAP sonocatalyst. The high degradation ratio of prometryn and disinfection ratio of E. coli showed that P-TET/OB-HAP could be a promising sonocatalyst for the degradation of organic pollutants and the disinfection of bacteria. © 2020 Society of Chemical Industry
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BIORESOURCE TECHNOLOGY
·
2020
·
IF 7.539
Guoyan Zhang,Hossain M. Zabed,Junhua Yun,Jiao Yuan,Yufei Zhang,Yang Wang,Xianghui Qi
In this study, a new strain of Lactobacillus plantarum (CY.6) was identified and its L-arabinose isomerase (L-AI) encoding gene ( ara A) was overexpressed in Escherichia coli BL21 for the biosynthesis of D-tagatose from milk whey powders (WP). Whole-cell biotransformation of lactose in WP into D-tagatose was done by three technological approaches, including 100%, 50% and 0% hydrolysis of lactose in WP before biotransformation, where simultaneous saccharification and biotransformation (SSB, 0% prior hydrolysis of lactose) produced maximum amounts of D-tagatose. Two-stage SSB provided 73.6% conversion efficiency (based on D-galactose) and 36.8% (in term of lactose), with 51.5 g/L of D-tagatose after 96 h, while concentration of D-tagatose produced after first stage was 34.4 g/L. Yield and volumetric productivity of D-tagatose after two-stage SSB were found to be 0.26 g/g of WP (0.37 g/g of lactose, 0.74 g/g of D-galactose produced from lactose) and 0.54 g/L/h, respectively.
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ADVANCED POWDER TECHNOLOGY
·
2019
·
IF 3.25
Linwei Ji,Baojiang Liu,Yajie Qian,Qing Yang,Pin Gao
Composites coupling different semiconductors have attracted increasing attention for photocatalytic application owing to low visible-light absorption capability and weak photocatalytic activity of the single-component system. In this study, Bi 2 WO 6 /TiO 2 /rGO ternary composites, successfully synthesized by a facile hydrothermal method, were manifested as an outstanding visible-light-response photocatalyst for the disinfection towards E. coli . X-ray diffraction, Fourier-transform infrared, and X-ray photoelectron spectroscopy demonstrated that GO coupled in the composites was efficiently reduced to rGO during the hydrothermal process, which was greatly beneficial for enhancing light harvest, promoting charge separation, and improving photocatalytic disinfection activity. UV–vis diffuse reflectance spectra, photoluminescence and time-resolved photoluminescence, photocurrent measurements, and ultraviolet photoelectron spectroscopy clearly showed that Bi 2 WO 6 /TiO 2 /rGO composites had narrower band gap energy and much better suppression capability of photoinduced electron-hole recombination in comparison to the pure Bi 2 WO 6 and TiO 2 , and Bi 2 WO 6 /TiO 2 . The radical trapping results revealed that the photogenerated holes (h + ) were the leading active species responsible for the effective inactivation of E. coli under visible-light irradiation. Hence, the underlying mechanism for the enhanced photocatalytic disinfection performance of Bi 2 WO 6 /TiO 2 /rGO composites was proposed. This study provides new insight into the design and development of composite materials with enhanced photocatalytic activity, which can be an inspiring alternative for environmental application.
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BIOSENSORS & BIOELECTRONICS
·
2018
·
IF 8.173
Miao Zhong,Lu Yang,Hui Yang,Chang Cheng,Wenfang Deng,Yueming Tan,Qingji Xie,Shouzhuo Yao
We report here cadmium sulfide quantum dots (CdS QDs)-encapsulated metal-organic frameworks as signal-amplifying tags for ultrasensitive electrochemical detection of Escherichia coli O157:H7 ( E. coli O157:H7). CdS QDs were encapsulated in zeolitic imidazolate framework-8 (ZIF-8) to form CdS@ZIF-8 muti-core-shell particles by in situ growth of ZIF-8 in the presence of CdS QDs. To specifically recognize E. coli O157:H7 cells, CdS@ZIF-8 particles were coated with polyethyleneimine to introduce amino groups on their surfaces, followed by surface modification of anti- E. coli O157:H7 antibody. A sandwich-type electrochemical immunobiosensor for the detection of E. coli O157:H7 was fabricated using CdS@ZIF-8 particles as signal tags. Cd(II) ions were released from CdS@ZIF-8 tags by HCl leaching, enabling the detection of E. coli O157:H7 by differential pulse voltammetry . Under the optimized conditions, the linear range of the biosensor is from 10 to 10 8 colony forming units (CFU) per mL for E. coli O157:H7 detection, with the detection limit of 3 CFU mL −1 ( S / N = 3). The sensitivity of the biosensor for E. coli O157:H7 detection using CdS@ZIF-8 particles as signal tags is 16 times that of a biosensor using CdS QDs as signal tags, because the number of CdS QDs labeled to each bacterial cell increases greatly resulting from a great number of CdS QDs encapsulated in each CdS@ZIF-8 label. This method was successfully used to detect E. coli O157:H7 in milk samples.
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BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
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2017
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IF 3.498
Lang-Hong Wang,Xin-An Zeng,Man-Sheng Wang,Charles S. Brennan,Deming Gong
In this work, modifications of cell membrane fluidity, fatty acid composition and fatty acid biosynthesis-associated genes of Escherichia coli ATCC 25922 ( E. coli ) and Staphylococcus aureus ATCC 6538 ( S. aureus ), during growth in the presence of naringenin (NAR), one of the natural antibacterial components in citrus plants, was investigated. Compared to E. coli , the growth of S. aureus was significantly inhibited by NAR in low concentrations. Combination of gas chromatography–mass spectrometry with fluorescence polarization analysis revealed that E. coli and S. aureus cells increased membrane fluidity by altering the composition of membrane fatty acids after exposure to NAR. For example, E. coli cells produced more unsaturated fatty acids (from 18.5% to 43.3%) at the expense of both cyclopropane and saturated fatty acids after growth in the concentrations of NAR from 0 to 2.20 mM. For S. aureus grown with NAR at 0 to 1.47 mM, the relative proportions of anteiso-branched chain fatty acids increased from 37.2% to 54.4%, whereas iso-branched and straight chain fatty acids decreased from 30.0% and 33.1% to 21.6% and 23.7%, respectively. Real time q-PCR analysis showed that NAR at higher concentrations induced a significant down-regulation of fatty acid biosynthesis-associated genes in the bacteria, with the exception of an increased expression of fabA gene. The minimum inhibitory concentration (MIC) of NAR against these two bacteria was determined, and both of bacteria underwent morphological changes after exposure to 1.0 and 2.0 MIC.
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MICROCHEMICAL JOURNAL
·
2024
·
IF 4.9
Jingya Cao,Bailu Liu,Zhihao Tao,Fubang Liu,Qilin Liu,Tianhua Li,Luhong Wen,Ning Gan
Rapid, accurate, and simultaneous detection of triphenylmethane (TPM) residues and their metabolites in aquaculture products is vital to ensure the safety of aquatic products. In this study, a novel Escherichia coli ( E. coli ) engineering bacteria-polydopamine (PDMS@PDA@ E. coli ) coated stir bar was prepared for the extraction and enrichment of malachite green (MG), leucomalachite green (LMG), crystal violet (CV), and leucocrystal violet (LCV), which are typical TPM drugs utilised in aquaculture. A PDMS stir bar was first modulated to show hydrophilic properties via plasma treatment to enhance the evenness and stability of PDA coating. Subsequently, the PDMS@PDA stir bar was adsorbed with E. coli to form PDMS@PDA@ E. coli coating, which showed enhanced extraction capacity and selectivity towards TPMs. These characteristics were due to the specific adsorption properties of TPM dyes by Gram-negative bacteria. A hand-held stirring device was installed with the stir bar for on-site extraction. To directly detect the eluted targets without separation, a portable mass spectrometer was utilised. Under the optimal conditions, the samples can be rapidly pretreated (within 30 min) and used for the analysis of 4 TPMs with a recovery of 77.8 %-97.0 % together with the detection limits of 0.13–0.38 μg/kg. These findings prove that the assay has potential application value and broad prospects for the on-site detection of TPM residues in fish.
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PLoS Pathogens
·
2024
·Vol. 20
·期 1
·e1011926
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IF 5.5
Zihao Wang,Ziming Jiang,Yu Zhang,Congwei Wang,Zhaoyang Liu,Zhankui Jia,Sudhanshu Bhushan,Jinjian Yang,Zhengguo Zhang
Uropathogenic Escherichia coli (UPEC) is the primary causative agent of urinary tract infections (UTIs) in humans. Moreover, as one of the most common bacterial pathogens, UPEC imposes a substantial burden on healthcare systems worldwide. Epithelial cells and macrophages are two major components of the innate immune system, which play critical roles in defending the bladder against UPEC invasion. Yet, the routes of communication between these cells during UTI pathogenesis are still not fully understood. In the present study, we investigated the role of membrane-bound nanovesicles (exosomes) in the communication between bladder epithelial cells and macrophages during UPEC infection, using an array of techniques such as flow cytometry, miRNA profiling, RNA sequencing, and western blotting. Moreover, our in vitro findings were validated in a mouse model of UPEC-induced cystitis. We found that UPEC infection induced the bladder epithelial MB49 cell line to secrete large numbers of exosomes (MB49-U-Exo), which were efficiently absorbed by macrophages both in vivo and in vitro. Assimilation of MB49-U-Exo induced macrophages to produce proinflammatory cytokines, including tumor necrosis factor (TNF)α. Exposure of macrophages to MB49-U-Exo reduced their phagocytic activity (by downregulating the expression of phagocytosis-related genes) and increased their rate of apoptosis. Mechanistically, we showed that MB49-U-Exo were enriched in miR-18a-5p, which induced TNFα expression in macrophages by targeting PTEN and activating the MAPK/JNK signaling pathway. Moreover, administration of the exosome secretion inhibitor GW4869 or a TNFα-neutralizing antibody alleviated UPEC-mediated tissue damage in mice with UPEC-induced cystitis by reducing the bacterial burden of the bladder and dampening the associated inflammatory response. Collectively, these findings suggest that MB49-U-Exo regulate macrophage function in a way that exacerbates UPEC-mediated tissue impairment. Thus, targeting exosomal -release or TNFα signaling during UPEC infection may represent promising non-antibiotic strategies for treating UTIs.
Urinary tract infections, which are typically caused by uropathogenic Escherichia coli (UPEC), affect over 150 million people each year, worldwide. Because the incidence of antibiotic resistance among UPEC strains is on the rise, urinary tract infections are becoming increasingly challenging to treat using this standard treatment method. Moreover, although the host immune response against UPEC has been intensively studied, the mechanism of communication between bladder epithelial cells and macrophages during UPEC infection remains largely unexplored. Here, we characterized the exosomes released from bladder epithelial cells following UPEC infection and evaluated their impact on macrophages. We demonstrated that bladder tissue destruction following excessive innate immune cell activation during UPEC infection may be driven by exosomes secreted from bladder epithelial cells. We further showed that pharmacologically inhibiting exosomal release from epithelial cells limited macrophage-associated inflammation, innate immune cell infiltration, and histopathological injuries in a mouse model of UPEC-induced cystitis. Collectively, our findings suggest that modulating exosome release represents a promising non-antibiotic therapy for UTIs.
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ANALYTICAL CHEMISTRY
·
2025
·
IF 6.7
Zirui Wang,Jilong Zheng,Min Li,Shujia Wang,Zhida Gao,Yan-Yan Song,Chenxi Zhao
Rapid and accurate detection of trace microbial pathogens is essential for human health, environmental monitoring, and food safety. Here, we report the development of a solid-state electrochemiluminescence (ECL) bacterial sensor based on a β-glycosidase (β-Gal)-triggered coreactant generation strategy. Leveraging a three-dimensional TiO2 nanotube array integrated with peroxidase-like MIL-53(Fe), glucose oxidase-like Au nanoparticles, and luminol, this sensor efficiently generates coreactants on-site, enabling sensitive glucose detection. As glucose is the primary product of β-Gal-catalyzed lactose hydrolysis, its concentration directly correlates with β-Gal enzymatic activity, thus allowing for the quantification of β-Gal via ECL signal intensity. Using enterohemorrhagic Escherichia coli (EHEC) as a model of food-borne pathogens, the sensor demonstrates rapid detection (30 min) with an ultralow LOD (0.8 CFU mL–1), representing the most sensitive label-free bacterial ECL sensor reported to date. Furthermore, the ECL electrode was applied for the detection of EHEC on raw salmon slices, underscoring its potential for food safety monitoring.
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JOURNAL OF BIOTECHNOLOGY
·
2024
·
IF 4.1
Bowen Shen,Lin Zhang,Yu Zhou,Feifei Song,Shengping You,Rongxin Su,Wei Qi
5-Hydroxytryptophan (5-HTP), a precursor of the neurotransmitter serotonin in mammals, has demonstrated efficacy in treating various diseases such as depression, fibromyalgia and obesity. However, conventional biosynthesis methods of 5-HTP are limited by low yield and high reagent and process costs. In this study, the strain C1T7-S337A/F318Y with optimized promoter distribution was obtained, and the 5-HTP yield was 60.30 % higher than that of the initial strain. An efficient fermentation process for 5-HTP synthesis was developed using strain C1T7-S337A/F318Y with whey powder as a substrate for cell growth and inducer production. Shake flask fermentation experiments yielded 1.302 g/L 5-HTP from 2.0 g/L L-tryptophan (L-Trp), surpassing the whole-cell biocatalysis by 42.86 %. Scale-up to a 5 L fermenter further increased the yield to 1.649 g/L. This fermentation strategy substantially slashed reagent cost by 95.39 %, providing a more economically viable and environmentally sustainable route for industrial biosynthesis of 5-HTP. Moreover, it contributes to the broader utilization of whey powder in various industries.
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JOURNAL OF DAIRY SCIENCE
·
2022
·
IF 4.225
Bolong Fang,Juan Peng,Gan Zhang,Keyu Xing,Wenyao Chen,Daofeng Liu,Shan Shan,Yonghua Xiong,Weihua Lai
ABSTRACT Escherichia coli O157:H7 is a type of hazardous bacteria in the field of food safety. A sensitive and effective method is urgently needed to detect it, avoiding enormous harm for the human health. In this study, we synthesized stable Ag + -doped gold nanoclusters (Ag-AuNC) with a fluorescence intensity 4.8 times stronger than that of AuNC. It was further demonstrated that Ag 0 existing in the AuNC core and a fraction of Ag + anchored on the AuNC shell eliminated the surface defects and improved the luminescent properties of AuNC. A combination of I 2 and I − was used to quench fluorescence-enhanced Ag-AuNC, which was first applied in ELISA for detecting E. coli O157:H7 to improve the sensitivity. In the presence of E. coli O157:H7, the biotinylated anti- E. coli O157:H7 mAb and streptavidin-alkaline phosphatase would be immobilized and catalyze l -ascorbic acid 2-phosphate sesquimagnesium salt hydrate to produce ascorbic acid. After addition of KIO 3 , I 2 /I − were generated. The I 2 could trigger oxidative etching of Ag-AuNC and I − could combine with Ag + to decrease the Ag + concentration of Ag-AuNC, which resulted in fluorescence quenching of Ag-AuNC. Under optimal conditions, the linear range of I 2 /I − -mediated fluorescence quenching of Ag-AuNC-based immunoassay for detecting E. coli O157:H7 was 3.3 × 10 3 to 10 6 cfu/mL, with a detection limit of 9.2 × 10 2 cfu/mL, 10.7-fold lower than that of the traditional ELISA. The proposed immunoassay exhibits excellent sensitivity, specificity, recovery, and accuracy, which is useful for quantitative detection of E. coli O157:H7 in food safety.
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FOOD CHEMISTRY
·
2020
·
IF 6.306
Yu-gang Shi,Run-run Zhang,Chen-min Zhu,Ming-feng Xu,Qing Gu,Rammile Ettelaie,Shan Lin,Yi-fan Wang,Xin-yi Leng
The objective of this study was to investigate the antibacterial activity and potential mechanism of alkyl gallates against Escherichia coli and Staphylococcus aureus . Results show that the length of the alkyl chain plays a pivotal role in eliciting the activity and octyl gallate (OG) exerted excellent bactericidal activity through a multiple bactericidal mechanism. OG functions against both bacteria through damaging bacterial cell wall integrity, permeating into cells and then interacting with DNA, as well as disturbing the activity of the respiratory electron transport chain to induce a high-level toxic ROS (hydroxyl radicals) generation and up-regulation of the ROS genes. Also, electrospun nanofibers with OG have unique superiorities for maintaining the freshness of the icefish (4 °C). This research not only provides a more in-depth understanding of the interaction between OG and microorganisms but also highlights the great promise of using OG as a safe multi-functionalized food additive for food preservations.
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