ULTRASONICS SONOCHEMISTRY
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2021
·
IF 7.491
Qiao He,Donghong Liu,Muthupandian Ashokkumar,Xingqian Ye,Tony Z. Jin,Mingming Guo
This study was aimed at providing new insights on the response of bacterial cell membranes to ultrasound exposure. Escherichia coli ( E. coli ) O157:H7 cells were exposed to different ultrasound treatments (power intensities of 64, 191, 372, and 573 W /cm 2 , frequency of 20 kHz, pulsed mode of 2 sec: 2 sec) and the dynamic changes in cell viability within 27 min were assessed. With an increase in ultrasonic intensity and prolonged duration, a 0.76–3.52 log CFU/mL reduction in E. coli populations was attained. The alterations in the sensitivity of ultrasound-treated cells to antimicrobial compounds were evaluated by exposure to thyme essential oil nanoemulsion (TEON). The treatment reduced the E. coli population by 2.16–7.10 log CFU/mL, indicating the effects of ultrasonic field on facilitating the antibacterial efficacy of TEON. Ultrasonic-treated E. coli cells also displayed remarkable morphological and ultrastructural damages with destroyed membrane integrity and misshaped cell structures, which was observed by electron microscopy analysis. Significant increase in outer and inner membrane permeability, along with the cytoplasmic leakage and membrane depolarization were assessed utilizing spectrophotometry. For the first time, significant reduction in the membrane fluidity in response to ultrasound exposure were investigated. Additional efforts in exploring the effect of ultrasonic field on some bacterial membrane compositions were performed with infrared spectroscopy. In this study, multiple lines of evidence effectively served to elucidate the alterations on cellular membrane structure and property during exposure to sonication that could extend our understanding of the antimicrobial molecular mechanisms of ultrasound.
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高影响因子
BIOMEDICAL MICRODEVICES
·
2015
·Vol. 17
·期 1
·1-8
·
IF 2.877
Yang Zhen,Sun Xue-cheng,Wang Tao,Lei Chong,Liu Yan,Zhou Yong,Lei Jian
A giant magnetoimpedance (GMI)-based biosensor was developed for detection of Escherichia coli (E. coli) O157: H7. The GMI sensor involving the sensing elements of Cr/Cu/NiFe/Cu/NiFe was fabricated by Micro Electro-Mechanical system (MEMS) technology, including thick photoresist lithography and electroplating. A separate Au film substrate as immunoplatform was used to capture E. coli O157:H7. The monoclonal mouse anti-E. coli antibody was immobilized on Au film substrate surface with a self-assembled layer. The different concentration E. coli O157:H7 (100, 300 and 500 cfu/ml) were combined with Dynabeads-antibody conjugates (DAC) respectively. DAC were prepared by conjugating streptavidin-coupled Dynabeads with biotin-labeled polyclonal mouse anti-E. coli antibodies. The classical sandwich assay was used for detection of E. coli O157:H7 targeted with Dynabeads by using antibody-antigen pair combination of biotin-streptavidin. The fundamental principle for detection of E. coli O157:H7 based on GMI sensor was that Dynabeads were employed as magnetic labels of E. coli O157:H7, and E. coli O157:H7 can be monitored by detecting the fringe field of Dynabeads using magnetic sensing elements. We observed that the GMI ratio were significantly improved due to the presence of E. coli O157:H7 combined with Dynabeads. The GMI ratio increased as the E. coli O157:H7 concentration increased. A lower detectable concentration of 100 cfu/ml was achieved in present work. The GMI-based biosensor provides a new method to rapid and sensitive detection E. coli O157:H7, which has a large potential for bio-application.
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BIOTECHNOLOGY & BIOTECHNOLOGICAL EQUIPMENT
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2021
·
IF 1.632
Yingxue Liao,Zhijian Ni,Jinyong Wu,Zhongkui Li,Yuanfei Ge,Xiangsong Chen,Jianming Yao
2'-Fucosyllactose (2'-FL) is one of the most important oligosaccharides in human milk. In this study, a glucose–glycerol mixed carbon source and the deletion of the genes arcA and iclR were attempted for the first time in engineered Escherichia coli to improve 2'-FL production. The highest 2'-FL titre of 5.04 g/L, almost 1.4 times higher than that in the control strain, was obtained in the arcA mutant strain using shake-flask culture. In addition, the arcA mutant showed a significantly reduced accumulation of acetate. However, the deletion of iclR and the double deletion of arcA/iclR provided no benefit in terms of 2'-FL biosynthesis. Overall, these results suggest that deletion of arcA could efficiently increase the 2'-FL yield in E. coli and could lay a foundation for more efficient and larger-scale production. Moreover, in shake-flask culture under optimal conditions, the 2'-FL titer reached a maximum value of 7.14 g/L.
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
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2022
·
IF 7.129
Li-Juan Feng,Kai-Xin Zhang,Zong-Lin Shi,Fan-Ping Zhu,Xian-Zheng Yuan,Wan-Song Zong,Chao Song
Microplastics (MPs) in natural environments undergo complex aging processes, changing their interactions with coexisting antibiotics, and posing unpredictable ecological risks. However, the joint toxicity of aged MPs (aMPs) and antibiotics to bacteria, especially at the molecular level, is unclear. In this study, non-thermal plasma technology was used to simultaneously simulate various radical oxidation and physical reactions that occur naturally in the environment, breaking the limitation of simple aging process in laboratory aging technologies. After aging, we investigated the altered properties of aMPs, their interactions with ciprofloxacin (CIP), and the molecular responses of E. coli exposed to pristine MPs (13.5 mg/L), aMPs (13.5 mg/L), and CIP (2 μg/L) individually or simultaneously. aMPs bound far more CIP to their surfaces than pristine MPs, especially in freshwater ecosystems. Notably, the growth of E. coli exposed to aMPs alone was inhibited, whereas pristine MPs exposure didn’t affect the growth of E. coli . Moreover, the most differentially expressed genes in E. coli were induced by the coexposure of aMPs and CIP. Although E. coli depended on chemotaxis to improve its flagellar rotation and escaped the stress of pollutants, the coexposure of aMPs and CIP still caused cell membrane damage, oxidative stress, obstruction of DNA replication, and osmotic imbalance in E. coli . This study filled the knowledge gap between the toxicity of aMPs and pristine MPs coexisting with antibiotics at the transcription level, helping in the accurate assessment of the potential risks of MPs to the environment.
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高影响因子
WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
·
2010
·Vol. 27
·期 1
·129-136
·
IF 1.082
Tang Xiaoling,Liu Ji,Wang Bo,Yu Hongwei
Thirty-one ester hydrolases were cloned from Escherichia coli K-12 and an efficient screening strategy was applied to screen and characterize them, emphasizing on their enantioselectivity. We are the first to investigate the enantioselectivity of these enzymes, although their activity had been reported by other researchers. The enzyme XL3 from gene b0349, XL10 from gene b0494, XL15 from gene b3412, XL27 from gene b2154 and XL31 from gene b3825 exhibited high activity towards p -nitrophenyl esters with short chain. The enzyme XL15 from gene b3412 was demonstrated for the first time to show high enantioselectivity to ( R )-1-phenylethyl acetate both in hydrolysis and esterification with enantioselectivity value ( E) > 100 at the conversion of 31.2 and 36.8%, respectively.
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SENSORS AND ACTUATORS B-CHEMICAL
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2020
·
IF 7.1
Pingyue Wang,Ancheng Wang,Md Mehedi Hassan,Qin Ouyang,Huanhuan Li,Quansheng Chen
In this study, we have design a new biosensor for E. coli, based on the fluorescence resonance energy transfer (FRET) between aptamer modified upconversion nanoparticles (UCNPs) as donors and layered tungsten disulfide (WS 2 ) nanosheets as the effective acceptor. The aptamer modified-UCNPs can be fetched nearest to the WS 2 surface, because of the potent van der Waals force between the nucleobases of aptamer and the basal plane of WS 2 . The spectral overlap between UCNPs fluorescence emission and WS 2 absorption permits the occurrence of FRET, resulted in quenching of upconversion fluorescence. In the presence of E. coli , the specific aptamer preferentially bind to E. coli , causing changes in the conformation of aptamer, a phenomenon directs the dissociation of mixing probe away from the surface of WS 2 nanosheets and therefore parts of the quenched fluorescence of UCNPs was retrieved. The fluorescence intensity increased with the raised concentration of E. coli . The aptasensor exhibited limitary over the concentration range 85 to 85 × 10 7 cfu mL −1 for E. coli and the detection limit (LOD) was 17 cfu mL −1 . In addition, the proposed biosensing method comprehended huge advantages including the facile operation procedure, high sensitivity and selectivity, which confer a great potential for the quantification of E. coli in medical diagnostics, food and environmental analysis.
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BMC BIOTECHNOLOGY
·
2017
·Vol. 17
·期 1
·1-11
·
IF 2.415
Chang Fei,Zhang Xianbing,Pan Yu,Lu Youxue,Fang Wei,Fang Zemin,Xiao Yazhong
Background β-Glucosidase has attracted substantial attention in the scientific community because of its pivotal role in cellulose degradation, glycoside transformation and many other industrial processes. However, the tedious and costly expression and purification procedures have severely thwarted the industrial applications of β-glucosidase. Thus development of new strategies to express β-glucosidases with cost-effective and simple procedure to meet the increasing demands on enzymes for biocatalysis is of paramount importance.Results Light activated cassette YF1/FixJ and the SRRz lysis system were successfully constructed to produce Bgl1A(A24S/F297Y), a mutant β-glucosidase tolerant to both glucose and ethanol. By optimizing the parameters for light induction, Bgl1A(A24S/F297Y) activity reached 33.22 ± 2.0 U/mL and 249.92 ± 12.25 U/mL in 250-mL flask and 3-L fermentation tank, respectively, comparable to the controls of 34.02 ± 1.96 U/mL and 322.21 ± 10.16 U/mL under similar culture conditions with IPTG induction. To further simplify the production of our target protein, the SRRz lysis gene cassette from bacteriophage Lambda was introduced to trigger cell autolysis. As high as 84.53 ± 6.79% and 77.21 ± 4.79% of the total β-glucosidase were released into the lysate after cell autolysis in 250 mL flasks and 3-L scale fermentation with lactose as inducer of SRRz. In order to reduce the cost of protein purification, a cellulose-binding module (CBM) from Clostridium thermocellum was fused into the C-terminal of Bgl1A(A24S/F297Y) and cellulose was used as an economic material to adsorb the fusion enzyme from the lysate. The yield of the fusion protein could reach 92.20 ± 2.27% after one-hour adsorption at 25 °C.Conclusion sWe have developed an efficient and inexpensive way to produce β-glucosidase for potential industrial applications by using the combination of light induction, cell autolysis, and CBM purification strategy.
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ANALYTICAL BIOCHEMISTRY
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2022
·
IF 3.191
Junfang Xia,Tong Bu,Pei Jia,Kunyi He,Xin Wang,Xinyu Sun,Li Wang
Polymerase chain reaction (PCR) is one of the most common methods for rapid monitoring of foodborne pathogens; however, it requires purified nucleic acid as a template . Conventional nucleic acid purification is a time-consuming and laborious process. To overcome this, we developed polydopamine nanospheres (PDA NPs)-assisted direct PCR for detecting Escherichia coli O157:H7 ( E. coli O157:H7). PDA NPs significantly enhanced PCR efficiency because of their strong interaction with PCR reagents, including polymerase and primers, thereby enabling regulation of the PCR performance. The optimal concentration and diameter for PDA NPs were 0.10 μg/μL and 504 nm, respectively. The PDA NPs-assisted direct PCR exhibited high sensitivity in E.coli O157:H7 detection. The detection limit of PDA NPs-assisted direct PCR was 6.7 × 10 4 CFU/mL, which was 10-fold lower than that of direct PCR (6.7 × 10 5 CFU/mL). Moreover, the sensor demonstrated excellent selectivity against E. coli O157:H7, with a negative reaction to eight other common pathogens. Most importantly, the PDA NPs-assisted direct PCR detected the order of 10 4−5 CFU/mL E.coli O157:H7 in milk, beef, and watermelon samples. No cultural enrichment was required, with the whole process taking <3 h. Therefore, PDA NPs-assisted direct PCR has tremendous potential in the rapid and sensitive detection of pathogens.
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APPLIED SPECTROSCOPY
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2022
·
IF 3.588
Heera Jayan,Hongbin Pu,Da-Wen Sun
Detection of bioactive metabolites produced by bacteria is important for identifying biomarkers for infectious diseases. In this study, a surface-enhanced Raman spectroscopy (SERS)-based technique was developed for the detection of bioactive metabolite indole produced by Escherichia coli (E. coli) in biological media. The use of highly sensitive Au@Ag core-shell nanoparticles resulted in the detection of indole concentration as low as 0.0886 mM in standard solution. The supplementation of growth media with 5 mM of exogenous tryptophan resulted in the production of a maximum yield of indole of 3.139 mM by E. coli O157:H7 at 37 °C. The growth of bacterial cells was reduced from 47.73 × 108 to 1.033 × 106 CFU/mL when the cells were grown in 0 and 10 mM exogenous tryptophan, respectively. The amount of indole in the Luria–Bertani (LB) media had an inverse correlation with the growth of cells, which resulted in a three-log reduction in the colony-forming unit when the indole concentration in the media was 20 times higher than normal. This work demonstrates that SERS is an effective and highly sensitive method for rapid detection of bioactive metabolites in biological matrix.
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Engineering
·
2022
·
IF 12.834
Yingbo Shen,Fupin Hu,Yongqiang Wang,Dandan Yin,Lu Yang,Yiqiang Chen,Chunyan Xu,Jiyun Li,Junyao Jiang,Xueyang Wang,Yulin Fu,Dongyan Shao,Dejun Liu,Tengfei Ma,Chang Cai,Zhangqi Shen,Shaolin Wang,Juan Li,Rong Zhang,Yuebin Ke,Congming Wu,Jianzhong Shen,Timothy R. Walsh,Yang Wang
Although carbapenem use is prohibited in animals in China, carbapenem-resistant Escherichia coli (CREC), especially New Delhi metallo-β-lactamase (NDM)-producing strains, are widely prevalent in food-producing animals. At present, the impact of livestock-associated CREC strains on human populations at the national level is unknown. Here, we conduct a retrospective cross-sectional study to investigate the prevalence of CREC from clinical settings across 22 Chinese provinces or municipalities and analyze anthropogenic factors associated with their presence. We also ascertain the bla NDM and bla KPC abundance among pig and chicken farms and present a detailed genomic framework for CREC of animal and human origin. Overall, 631/29 799 (2.1%) clinical Escherichia coli ( E. coli ) isolates were identified as CREC. Multivariable analysis revealed that being male, an age below 1, an age between 13 and 18, provinces with greater chicken production, and provinces with higher pig production were associated with higher odds of CREC infection. In general, 73.8% ( n = 45/61) of pig farms and 62.2% ( n = 28/45) of chicken farms had a bla NDM abundance of 1 × 10 −5 to 1 × 10 −3 and 1 × 10 −3 to 1 × 10 −2 , respectively. Among all the Chinese NDM-positive E. coli ( n = 463) available at the National Center for Biotechnology Information (NCBI), the genomic analysis revealed that bla NDM-5 and IncX3 were the predominant carbapenemase gene-plasmid combination, while a highly homogeneous relationship between NDM-positive isolates from humans and animals was demonstrated at the plasmid and core genome levels. All the findings suggest frequent CREC transmission between humans and animals, indicating that further discussions on the use of antibiotics in animals and humans are needed, both in China and across the globe.
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Microbial Cell Factories
·
2024
·Vol. 23
·期 1
·1-13
·
IF 4.3
Zhao Siyu,Shi Tangen,Li Liangwen,Chen Zhichao,Li Changgeng,Yu Zichen,Sun Pengjie,Xu Qingyang
Background Hypoxanthine, prevalent in animals and plants, is used in the production of food additives, nucleoside antiviral drugs, and disease diagnosis. Current biological fermentation methods synthesize quantities insufficient to meet industrial demands. Therefore, this study aimed to develop a strain capable of industrial-scale production of hypoxanthine. Results De novo synthesis of hypoxanthine was achieved by blocking the hypoxanthine decomposition pathway, thus alleviating transcriptional repression and multiple feedback inhibition, and introducing a purine operon from Bacillus subtilis to construct a chassis strain. The effects of knocking out the IMP(Inosine 5’-monophosphate) branch on the growth status and titer of the strain were then investigated, and the effectiveness of adenosine deaminase and adenine deaminase was verified. Overexpressing these enzymes created a dual pathway for hypoxanthine synthesis, enhancing the metabolic flow of hypoxanthine synthesis and preventing auxotrophic strain formation. Introducing IMP-specific 5’ -nucleotidase addressed the issue of adenylate accumulation. In addition, the metabolic flow of the guanine branch was dynamically regulated by the guaB gene. The supply of glutamine and aspartic acid precursors was enhanced by introducing an exogenous glnA mutant gene, overexpressing aspC , and replacing the weaker promoter to regulate the aspartic acid branching pathway. Ultimately, fermentation in a 5 L bioreactor for 48 h produced 30.6 g/L hypoxanthine, with a maximum real-time productivity of 1.4 g/L/h, the highest value of hypoxanthine production by microbial fermentation reported so far. Conclusions The intracellular purine biosynthesis pathway is extensive and regulated at multiple levels in cells. The IMP branch in the hypoxanthine synthesis pathway has a higher metabolic flux. The current challenge lies in systematically allocating the metabolic flux within the branch pathway to achieve substantial product accumulation. In this study, E. coli was used as the chassis strain to construct a dual pathway for IMP and AMP(Adenosine 5’-monophosphate) synergistic hypoxanthine synthesis and dynamically regulate the guanine branch pathway. Overall, our experimental efforts culminated in a high-yield, plasmid- and defect-free engineered hypoxanthine strain.
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PeerJ
·
2024
·
IF 2.3
Chunyu Tong,Yimin Liang,Qi Liu,Honghao Yu,Wenzhi Feng,Bocui Song
Background Bacteria can develop resistance to various antibiotics under selective pressure, leading to multifaceted changes in resistance mechanisms. Transcriptomic sequencing allows for the observation of transcriptional level alterations in cells under antibiotic stress. Understanding the bacterial response to such stress is essential for deciphering their strategy against drug-resistant antibiotics and identifying potential targets for antibiotic development. Methods This study using wild-type (WT) Escherichia coli ( E. coli ) discovered that continuous in vitro induction screening for imipenem-resistant strains resulted in bacteria with enhanced biofilm-forming ability and mutations in antibiotic target sites. Transcriptomic sequencing of the resistant bacteria revealed significant changes in carbon and amino acid metabolism, nutrient assimilation, substance transport, nucleotide metabolism, protein biosynthesis, and cell wall biosynthesis. The up-regulated drug efflux genes were disrupted using gene knockout technology. Drug sensitivity tests indicated that drug efflux has a minimal effect on imipenem resistance. Results This suggests a strategy for E. coli drug resistance involving the reduction of unnecessary substance synthesis and metabolism, coupled with an increase in activities that aid in resisting foreign threats.
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