SENSORS AND ACTUATORS B-CHEMICAL
·
2021
·
IF 7.46
Shuai Zhao,Tuoyu Zhou,Aman Khan,Zhengjun Chen,Pu Liu,Xiangkai Li
Electrochemical enzyme biosensors based on various modified electrodes have been developed for bisphenol A detection. However, enzyme activity loss and high cost limit their application. In this study, an electrochemical biosensor was developed for bisphenol A detection by displaying tyrosinase on the surface of Escherichia coli cells, followed by adsorption onto a glassy-carbon electrode. The biosensor exhibited a linear relationship between the concentration range of 0.01–100 nM BPA (R 2 = 0.9967) and the current peak. The detection limit was 0.01 nM, which is higher than that of other chemically modified tyrosinase biosensors. For the detection of bisphenol A in tea and juice samples, the fabricated biosensor presented respectable accuracy comparable to that of high-performance liquid chromatography. Furthermore, high recovery rates (97.78%−100.32%) were obtained. Therefore, this biosensor could be a promising and reliable analytical tool for the detection of bisphenol A.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2023
·
IF 6.1
Dongxu Yuan,Bingbing Liu,Xinsong Yuan,Leilei Feng,Xudong Xu,Jialin Zhu,Zhengjie Chen,Renhao Xu,Jiao Chen,Gang Xu,Jianping Lin,Lirong Yang,Mian Li,Jiazhang Lian,Mianbin Wu
The bioproduction of xylitol from hemicellulose hydrolysate has good potential for industrial development. However, xylitol productivity has always been limited due to corncob hydrolysate toxicity and glucose catabolic repression. To address these challenges, this work selected the S83 and S128 amino acid residues of the cyclic AMP receptor protein (CRP) as the modification target. By introducing multisite mutation in CRP, this approach successfully enhanced xylose catabolism and improved the strain’s tolerance to corncob hydrolysate. The resulting mutant strain, designated as CPH (CRP S83H-S128P), underwent fermentation in a 20 L bioreactor with semicontinuous feeding of corncob hydrolysate. Remarkably, xylitol yield and xylitol productivity for 41 h fermentation were 175 and 4.32 g/L/h, respectively. Therefore, multisite CRP mutation was demonstrated as an efficient global regulatory strategy to effectively improve xylitol productivity from lime-pretreated corncob hydrolysates.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Hongyan Shen,Yingying Liu,Yinan Liu,Zemeng Duan,Pengpeng Wu,Zhifen Lin,Haoyu Sun
Silver antibacterial compounds (SACs) and quorum sensing inhibitors (QSIs), as the potential antibiotic substitutes, have been recommended to prevent and treat microbial infections for the purpose of controlling the increasingly serious bacterial resistance induced by the abuse of antibiotics. However, there is little information regarding the resistance risk of these compounds, especially their mixtures. In this study, bacterial mutation and RP4 plasmid conjugative transfer among bacteria were used to characterize the bacterial endogenous and exogenous resistance, respectively. The effects of SACs (including silver nitrate (AgNO 3 ) and silver nanoparticle (AgNP)), QSIs, and their binary mixtures on the bacterial resistance were investigated via setting the frequency of mutation and conjugative transfer in Escherichia coli ( E. coli ) as the test endpoints. The results indicated that these two endpoints exhibited hormetic dose-responses to each treatment. Furthermore, the joint resistance actions between SACs and QSIs were all judged to be antagonism. Correlation analysis suggested that the promotion of the bacterial resistance in each treatment was closely related to its toxicity. It was speculated that AgNO 3 and AgNP might both release Ag + ions to facilitate the E. coli resistance, while QSIs probably acted on LsrR and SdiA proteins to stimulate the bacterial mutation and accelerate the RP4 plasmid conjugative transfer, respectively. These findings imply that the bacteria may generate targeted stress response to the survival pressure from environmental compounds, displaying hormetic phenomenon in resistance-related test endpoints. This study provides a new insight into the resistance risk induced by SACs and QSIs, benefiting the environmental risk assessment of these compounds from the perspective of bacterial resistance.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2021
·
IF 7.46
Yuanyang Xie,Yu Huang,Jiye Li,Jiangling Wu
A pH-triggered colorimetric assay has been established by using aptamer anchored gold nanoparticles to detect Escherichia coli O157:H7 ( E. coli O157:H7). Gold nanoparticles (AuNPs) functionalized by aptamer via thiol groups were used as probes ( [email protected] ).Solvents of HCl (acid), NaOH (alkaline) and MgCl 2 (nearly neutral) were used as triggers to initiate the movement of [email protected] in the presence of E. coli O157:H7 bacteria respectively. Due to the pH effect of trigger on the surface charges of E. coli O157:H7 and the contribution of aptamer to capture E. coli O157:H7, the movement of [email protected] with the presence of E. coli O157:H7 exhibit dispersion and aggregation respectively, which leads the change of colorimetric signal to an opposite direction. Taking the solvent of NaCl frequently used as trigger for gold nanoparticle based colorimetric sensor into consideration, the utilization of pH dependent triggers provide an alternative for this kind of trigger-based sensor. Design of gold nanoparticle-based colorimetric biosensing assay suiting a wide range of trigger is more flexible for specific diagnosis. These results demonstrate a great potential to design bacterial sensor with high sensitivity to defend public health.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2020
·Vol. 193
·期 3
·717-729
·
IF 2.277
Zhang Jun,Tian Miao,Chen Xiaoyan,Lv Pengmei,Luo Wen,Wang Zhiyuan,Xu Jingliang,Wang Zhongming
Biodiesel biosynthesis with enzymatic transesterification is considered green, sustainable, and environmentally friendly method. Lipase from Burkholderia cepacia G63 has excellent catalytic properties in biodiesel production. Lipase chaperones promote secretion and folding of enzymes, thereby enhancing enzymatic activity. In the current study, heterologous co-expression of lipase (lipA) and chaperone (lipB) was achieved in Escherichia coli through codon optimization. The enzymatic activity of purified and renatured lipAB was 2080.23 ± 19.18 U/g at 50 °C and pH 8.0. Moreover, lipAB showed increased resistance to pH and temperature changes, and lipAB retained stable catalytic properties after treatment with metal ions, organic solvents, and surfactants, namely Mg 2+ , methanol, and Triton-100X. Besides, using recombinant lipase lipAB as catalysts, biodiesel was synthesized using rapeseed oil under 50 °C for 72 h with a yield of 90.23%. Thus, the current study confirmed that co-expression of lipase and its chaperone is an effective strategy to enhance enzyme activity and improve the biochemical profile, meanwhile, showing that lipAB is a promising biocatalyst for biodiesel production.
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ENZYME AND MICROBIAL TECHNOLOGY
·
2020
·
IF 3.448
Cun-Duo Tang,Hong-Ling Shi,Yuan-Yuan Jia,Xiang Li,Lin-Feng Wang,Jian-He Xu,Lun-Guang Yao,Yun-Chao Kan
L -Phenylglycine ( L -PHG) is a member of unnatural amino acids, and becoming more and more important as intermediate for pharmaceuticals, food additives and agrochemicals. However, the existing synthetic methods for L -PHG mainly rely on toxic cyanide chemistry and multistep processes. To provide green, safe and high enantioselective alternatives, we envisaged cascade biocatalysis for the one-pot synthesis of L -PHG from racemic mandelic acid. A engineered E. coli strain was established to co-express mandelate racemase, D -mandelate dehydrogenase and L -leucine dehydrogenase and catalyze a 3-step reaction in one pot, enantioselectively transforming racemic mandelic acid to give L -PHG ( e.e. >99 %). After the conditions for biosynthesis of L -PHG optimized by response surface methodology, the yield and space-time yield of L -PHG can reach 87.89 % and 79.70 g·L −1 ·d −1 , which was obviously improved. The high-yielding and enantioselective synthetic methods use cheap and green reagents, and E. coli whole-cell catalysts, thus providing green and useful alternative methods for manufacturing L -PHG.
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CHIRALITY
·
2018
·Vol. 30
·期 7
·907-912
·
IF 1.833
Jianyong Zheng,Xing Lan,Lijuan Huang,Yinjun Zhang,Zhao Wang
D-alanine is widely used in medicine, food, additives, cosmetics, and other consumer items. Esterase derived from Bacillus cereus WZZ001 exhibits high hydrolytic activity and stereoselectivity. In this study, we expressed the esterase gene in Escherichia coli BL21 (DE3). We analyzed the biocatalytic resolution of N-acetyl-DL-alanine methyl ester by immobilized whole E . coli BL21 (DE3) cells, which were prepared through embedding and cross-linking. We analyzed biocatalytic resolution under the optimal conditions of pH of 7.0, temperature of 40°C and substrate concentration of at 700 mM with an enantiomeric excess of 99.99% and e.e. p of 99.50%. The immobilized recombinant B . cereus esterase E . coli BL21 (DE3) cells exhibited excellent reusability and retained 86.04% of their initial activity after 15 cycles of repeated reactions. The immobilized cells are efficient and stable biocatalysts for the preparation of N-acetyl-D-alanine methyl esters.
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CHINESE CHEMICAL LETTERS
·
2018
·
IF 2.631
Rongqiao Chen,Chune Guo,Wubo Chu,Nan Jiang,He Li
Marine microorganism accumulated on the surface of ships or pipelines would accelerate fouling organisms, such as mussels and barnacles, adhered on the surface. It was significant to understand the bio-interaction between the microorganisms and the surface. Attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy was used to study the initial stages of marine microorganism adhering to surfaces, because it could probe the microorganism interaction to the surface regardless of the water interference. Bacillus sp. and Escherichia coli were selected to study the initial attachment on different surfaces, because they were typical fouling microorganisms and showed opposite Gram stain results. The assays were conducted respectively in dried and settled bacteria on two different surfaces (ZnSe, Al 2 O 3 coated on ZnSe). IR spectra of settled bacteria showed amide I band red shift and amide II band blue shift in aqueous environment on both surfaces compared with the dry bacteria. The reasons of amide bands shift were investigated and it was discovered that the hydrogen bond between the water and the protein of the bacteria led to the protein secondary structure change. ATR-FTIR provided an approach to study the attachment process and showed dynamic changing process on the surface, and it could be an appropriate approach to study the interaction between proteins and chemicals.
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LWT-FOOD SCIENCE AND TECHNOLOGY
·
2018
·
IF 3.129
Xueyan Ren,Peipei An,Xin Zhai,Shuo Wang,Qingjun Kong
Antibiotic overuse has caused concerns owing to the emergence of antibiotic resistant microorganisms and the accompanying decreased bacteria-inhibiting effectiveness of proffered treatments. Pterostilbene, derived from XinJiang wine grape, is a natural polyphenol, and has attracted considerable attention for its promising antifungal effects. However, its inhibitory activities and mechanisms of action against bacteria are still unknown. In this study, pterostilbene inhibited the growth of Gram-positive Staphyloccocus aureus and Gram-negative Escherichia coli effectively. Electron microscope observations showed that the morphological structures of S. aureus and E. coli were significantly damaged by pterostilbene. Cells became irregular, shriveled, and lysed, while nucleic acids and proteins leaked, and DNA content decreased. Furthermore, confocal laser scanning microscopy experiments revealed that bacteria treated with pterostilbene produced reactive oxygen species, and the cytomembrane potential increased. To further clarify the molecular mechanism, changes in the expression levels of four genes in two bacteria were confirmed by qRT-PCR. Pterostilbene cause the up-regulation of DinF (an oxidative stress gene). An associated down-regulation of PaL, MtgA, and NagA (genes involved in cell wall synthesis) is also attributed to pterostilbene treatment. This is the first time that the mechanism of pterostilbene against S. aureus and E. coli is presented in literature.
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BIOSENSORS & BIOELECTRONICS
·
2018
·
IF 8.173
Lingyan Zheng,Gaozhe Cai,Siyuan Wang,Ming Liao,Yanbin Li,Jianhan Lin
We intended to develop a novel biosensor using gold nanoparticles (AuNPs) for indicating different concentrations of E. coli O157:H7 and smart phone imaging APP for monitoring color change of the AuNPs. The magnetic nanoparticles (MNPs) modified with the capture antibodies and the polystyrene microspheres (PSs) modified with the detection antibodies and the catalases were simultaneously used to react with the target bacteria in the first mixing channel of the microfluidic chip, and hydrogen peroxide was injected and catalyzed by the catalases on the MNP-bacteria-PS complexes. After the mixture of the AuNPs and the crosslinking agents were injected to react with the catalysate in the second mixing channel and incubated in the detection chamber, the aggregation of the AuNPs was triggered through the crosslinking agents, resulting in the color of the AuNPs changing from blue to red. Finally, the color was measured using the smart phone imaging APP to determine the amount of the bacteria. This biosensor exhibited a good specificity and sensitivity for detection of E. coli O157:H7 in chicken samples with a lower detection limit of 50 CFU/mL.
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WATER RESEARCH
·
2015
·
IF 5.528
Yujiao Long,Jinren Ni,Zuhui Wang
Although the identification of effective oxidant species has been extensively studied, yet the subcellular mechanism of bacterial inactivation has never been clearly elucidated in electrochemical disinfection processes. In this study, subcellular mechanism of Escherichia coli inactivation during electrochemical disinfection was revealed in terms of comprehensive factors such as cell morphology, total organic components, K + leakage , membrane permeability, lipid peroxidation, membrane potential, membrane proteins, intracellular enzyme, cellular ATP level and DNA. The electrolysis was conducted with boron-doped diamond anode in three electrolytes including chloride, sulfate and phosphate. Results demonstrated that cell inactivation was mainly attributed to damage to the intracellular enzymatic systems in chloride solution. In sulfate solution, certain essential membrane proteins like the K + ion transport systems were eliminated. Thus, the pronounced K + leakage from cytosol resulted in gradual collapse of the membrane potential, which would hinder the subcellular localization of cell division-related proteins as well as ATP synthesis and thereby lead to the bacterial inactivation. Remarkable lipid peroxidation was observed, while the intracellular damage was negligible. In phosphate solution, the cells sequentially underwent overall destruction as a whole cell with no captured intermediate state, during which the organic components of the cells were mostly subjected to mineralization . This study provided a thorough insight into the bacterial inactivation mechanism on the subcellular level.
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JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION
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2013
·
IF 1.7
Fei Zhang,Juan Wu,Ding Kang,Hongbin Zhang
Novel nanocomposite hydrogels composed of hyaluronan (HA), poly(vinyl alcohol) (PVA) and silver nanoparticles were prepared by several cycles of freezing and thawing. The nanocomposite was then characterised using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD) and scanning electron microscopy (SEM). The complex hydrogels consisted of semi-interpenetrating network structures, with PVA microcrystallines as junction zones. By increasing the HA content, the crystallinity and melting temperature of the complex hydrogels decreased, whereas the glass transition temperatures of these materials increased because of the steric hindrance of HA and the occurrence of intermolecular interactions through hydrogen bonding between HA and PVA in the complex hydrogels. Swelling studies showed that in comparison with the swelling properties of the cryogels from PVA alone, those of the complex hydrogels can be significantly improved and presented in a pH-sensitive manner. In addition, silver nanoparticles were synthesised through UV-initiated photoreduction with HA functioning as a reducing agent and stabiliser. The silver nanoparticles were then incorporated in situ into the HA/PVA complex hydrogel matrix. The size and morphology of the as-prepared Ag nanoparticles were investigated through ultraviolet–visible light spectroscopy, transmission electron microscopy, XRD and thermogravimetric analysis. The experimental results indicated that silver nanoparticles 20–50 nm in size were uniformly dispersed in the hydrogel matrix. The antibacterial effects of the HA/PVA/Ag nanocomposite hydrogel against Escherichia coli were evaluated. The results show that this nanocomposite hydrogel possesses high antibacterial property and has a potential application as a wound dressing material.
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