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https://www.readbyqxmd.com/read/28646720/nanoporous-gold-based-microbial-biosensor-for-direct-determination-of-sulfide
#1
Zhuang Liu, Hanyue Ma, Huihui Sun, Rui Gao, Honglei Liu, Xia Wang, Ping Xu, Luying Xun
Environmental pollution caused by sulfide compounds has become a major problem for public health. Hence, there is an urgent need to explore a sensitive, selective, and simple sulfide detection method for environmental monitoring and protection. Here, a novel microbial biosensor was developed using recombinant Escherichia coli BL21 (E. coli BL21) expressing sulfide:quinone oxidoreductase (SQR) for sulfide detection. As an important enzyme involved in the initial step of sulfide metabolism, SQR oxidizes sulfides to polysulfides and transfers electrons to the electron transport chain...
June 20, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28646667/prevalence-and-characterization-of-extended-spectrum-%C3%AE-lactamase-esbl-and-ampc-%C3%AE-lactamase-producing-enterobacteriaceae-in-fresh-pork-meat-at-processing-level-in-germany
#2
Franziska Schill, Amir Abdulmawjood, Günter Klein, Felix Reich
ESBL or AmpC β-lactamase producing Enterobacteriaceae is an increasing concern in human medicine. A distribution via the food chain is discussed, but less is known about these bacteria on fresh pork meat. The aim of this study was to investigate the prevalence of ESBL/AmpC Enterobacteriaceae bacteria in fresh pork meat at processing level in Germany. The analysis comprised microbiological hygiene parameters and further pheno- and genotypical characterization of ESBL/AmpC isolates. The examination included three pools of meat and one corresponding meat juice sample from each of the tested pork meat batches (n=63)...
June 15, 2017: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/28646502/the-liver-gut-microbiota-axis-modulates-hepatotoxicity-of-tacrine-in-the-rat
#3
Lian Yee Yip, Chiu Cheong Aw, Sze Han Lee, Yi Shuen Hong, Han Chen Ku, Winston Hecheng Xu, Jessalyn Mei Xuan Chan, Eleanor Jing Yi Cheong, Kern Rei Chng, Amanda Hui Qi Ng, Niranjan Nagarajan, Ratha Mahendran, Yuan Kun Lee, Edward R Browne, Eric Chun Yong Chan
The gut microbiota possesses diverse metabolic activities but its contribution towards heterogeneous toxicological responses is poorly understood. Here, we elucidate the role of the liver-gut microbiota axis in underpinning the hepatotoxicity of tacrine. We employed an integrated strategy combining pharmacokinetics, toxicology, metabonomics, genomics and metagenomics to elucidate and validate the mechanism of tacrine-induced hepatotoxicity in Lister hooded rats. Pharmacokinetic studies in rats demonstrated 3...
June 23, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/28646449/occurrence-of-pepper-mild-mottle-virus-pmmov-in-groundwater-from-a-karst-aquifer-system-in-the-yucatan-peninsula-mexico
#4
Gabriela Rosiles-González, Gerardo Ávila-Torres, Oscar A Moreno-Valenzuela, Gilberto Acosta-González, Rosa María Leal-Bautista, Cinthya D Grimaldo-Hernández, Judith K Brown, Cristóbal Chaidez-Quiroz, Walter Q Betancourt, Charles P Gerba, Cecilia Hernández-Zepeda
The Yucatan Peninsula of Mexico hosts a karst aquifer system that is the only source of freshwater for the area; however, it is vulnerable to human-mediated contamination. Pepper mild mottle virus (PMMoV) is one of the most abundant RNA viruses associated with human feces, making it a viable indicator for tracking fecal pollution in aquatic environments, including groundwater. In this study, groundwater samples collected from a karst aquifer from fresh and brackish water locations were analyzed for fecal indicator bacteria, somatic and male F+ specific coliphages, and PMMoV during the rainy and dry seasons...
June 23, 2017: Food and Environmental Virology
https://www.readbyqxmd.com/read/28646435/eco-friendly-synthesis-of-silver-nanoparticles-using-green-algae-caulerpa-serrulata-reaction-optimization-catalytic-and-antibacterial-activities
#5
Eman F Aboelfetoh, Rania A El-Shenody, Mohamed M Ghobara
Stable colloidal silver nanoparticles (AgNPs) were synthesized using Caulerpa serrulata (green marine algae) aqueous extract as an efficient reducing and stabilizing agent. This method is considered to be a sustainable alternate to the more complicated chemical procedures. To achieve the optimization synthesis of AgNPs, several effects such as extract concentration, contact time, pH values, and temperature were examined. The synthesized AgNPs were characterized by UV-Vis spectroscopy, FT-IR, XRD, and HR-TEM...
July 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28646326/transposable-elements-mediate-adaptive-debilitation-of-flagella-in-experimental-escherichia-coli-populations
#6
Gordon R Plague, Krystal S Boodram, Kevin M Dougherty, Sandar Bregg, Daniel P Gilbert, Hira Bakshi, Daniel Costa
Although insertion sequence (IS) elements are generally considered genomic parasites, they can mediate adaptive genetic changes in bacterial genomes. We discovered that among 12 laboratory-evolved Escherichia coli populations, three had experienced at least six different IS1-mediated deletions of flagellar genes. These deletions all involved the master flagellar regulator flhDC, and as such completely incapacitate motility. Two lines of evidence strongly suggest that these deletions were adaptive in our evolution experiment: (1) parallel evolution in three independent populations is highly unlikely just by chance, and (2) one of these deletion mutations swept to fixation within ~1000 generations, which is over two million times faster than expected if this deletion was instead selectively neutral and thus evolving by genetic drift...
June 23, 2017: Journal of Molecular Evolution
https://www.readbyqxmd.com/read/28646205/comparative-nanouplc-ms-e-analysis-between-magainin-i-susceptible-and-resistant-escherichia-coli-strains
#7
Marlon H Cardoso, Keyla C de Almeida, Elizabete de S Cândido, André M Murad, Simoni C Dias, Octávio L Franco
In recent years the antimicrobial peptides (AMPs) have been prospected and designed as new alternatives to conventional antibiotics. Indeed, AMPs have presented great potential toward pathogenic bacterial strains by means of complex mechanisms of action. However, reports have increasingly emerged regarding the mechanisms by which bacteria resist AMP administration. In this context, we performed a comparative proteomic study by using the total bacterial lysate of magainin I-susceptible and -resistant E. coli strains...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28646154/investigation-of-the-removal-mechanism-of-antibiotic-ceftazidime-by-green-algae-and-subsequent-microbic-impact-assessment
#8
Ying Yu, Yangyang Zhou, Zhiliang Wang, Oscar Lopez Torres, Ruixin Guo, Jianqiu Chen
The present study provides an integrated view of algal removal of the antibiotic ceftazidime and its basic parent structure 7-aminocephalosporanic acid (7-ACA), including contribution analysis, bacteriostatic and aquatic toxic assessment and metabolite verification. 92.70% and 96.07% of the two target compounds was removed after the algal treatment, respectively. The algal removal can be separated into three steps: a rapid adsorption, a slow cell wall-transmission and the final biodegradation. Additionally, while ceftazidime demonstrated an excellent inhibitory effect on Escherichia coli, there was no bacteriostasis introduced after the algal treatment, which could avoid favoring the harmful selective pressure...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28646114/staphylococcus-aureus-strain-newman-photoinactivation-and-cellular-response-to-sunlight-exposure
#9
Jill S McClary, Lauren M Sassoubre, Alexandria B Boehm
Sunlight influences microbial water quality of surface waters. Previous studies have investigated photoinactivation mechanisms and cellular photostress responses of fecal indicator bacteria (FIB), including Escherichia coli and enterococci, but further work is needed to characterize photostress responses of bacterial pathogens. Here we investigate the photoinactivation of Staphylococcus aureus (strain Newman), a pigmented, waterborne pathogen of emerging concern. We measured photodecay using standard culture-based assays and cellular membrane integrity; and investigated photostress response by measuring the relative number of mRNA transcripts of select oxidative stress, DNA repair, and metabolism genes...
June 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28646112/crispr-cas12a-assisted-recombineering-in-bacteria
#10
Mei-Yi Yan, Hai-Qin Yan, Gai-Xian Ren, Ju-Ping Zhao, Xiao-Peng Guo, Yi-Cheng Sun
Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas12a (Cpf1) has emerged as an effective genome editing tool in many organisms. Here, we developed and optimized a CRISPR-Cas12a assisted recombineering system to facilitate genetic manipulation in bacteria. Using this system, point mutations, deletions, insertions, and gene replacements can be easily generated on the chromosome or native plasmids in Escherichia coli, Yersinia pestis, and Mycobacterium smegmatis Because CRISPR-Cas12a-assisted recombineering does not require introduction of an antibiotic resistance gene into the chromosome to select for recombinants, it is an efficient approach for generating markerless and scarless mutations in bacteria...
June 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28646111/a-bacillus-paralicheniformis-iron-containing-urease-reduces-urea-concentrations-in-rice-wine
#11
Qingtao Liu, Yuqi Chen, Minglai Yuan, Guocheng Du, Jian Chen, Zhen Kang
Urease, as a nickel-containing metalloenzyme, was the first enzyme to be crystallized, and it has a prominent position in the history of biochemistry. In the present study, we identified a nickel urease gene cluster, ureABCEFGDH, from Bacillus paralicheniformis ATCC 9945a and characterized it in Escherichia coli Enzymatic assays demonstrate that this oxygen-stable urease is also an iron-containing acid urease. UreH heterologous expression assays suggest that this accessory protein is involved in transmembrane transportation of nickel and iron ions...
June 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28645718/optimizing-adjuvants-for-intradermal-delivery-of-menc-glycoconjugate-vaccine
#12
Agnese Donadei, Cristiana Balocchi, Maria R Romano, Luigi Panza, Roberto Adamo, Francesco Berti, Derek T O'Hagan, Simona Gallorini, Barbara C Baudner
Intradermal vaccine delivery is a promising alternative to the conventional intramuscular route. The skin layer is immunologically supported by a densely network of antigen presenting cells, while the skeletal muscle is loaded with a relatively sparse population of APCs. Nevertheless, the vaccine to be suitable for intradermal delivery needs a new formulation to facilitate either smaller injection volumes or the introduction into new delivery devises as micro-needles. This study presents a proof of concept for intradermal delivery of the MenC-CRM197 glycoconjugate vaccine using a mouse model...
June 20, 2017: Vaccine
https://www.readbyqxmd.com/read/28645581/improvement-of-isopropanol-tolerance-of-escherichia-coli-using-adaptive-laboratory-evolution-and-omics-technologies
#13
Takaaki Horinouchi, Aki Sakai, Hazuki Kotani, Kumi Tanabe, Chikara Furusawa
Isopropanol (IPA) is the secondary alcohol that can be dehydrated to yield propylene. To produce IPA using microorganisms, a significant issue is that the toxicity of IPA causes retardation or inhibition of cell growth, decreasing the yield. One possible strategy to overcome this problem is to improve IPA tolerance of production organisms. For the understanding of tolerance to IPA, we performed parallel adaptive laboratory evolution (ALE) of Escherichia coli under IPA stress. To identify the genotypic change during ALE, we performed genome re-sequencing analyses of obtained tolerant strains...
June 20, 2017: Journal of Biotechnology
https://www.readbyqxmd.com/read/28645580/chemostat-studies-of-bacteriophage-m13-infected-escherichia-coli-jm109-for-continuous-ssdna-production
#14
Benjamin Kick, Karl Lorenz Behler, Timm Steffen Severin, Dirk Weuster-Botz
Steady state studies in a chemostat enable the control of microbial growth rate at defined reaction conditions. The effects of bacteriophage M13 infection on maximum growth rate of Escherichia coli JM109 were studied in parallel operated chemostats on a milliliter-scale to analyze the steady state kinetics of phage production. The bacteriophage infection led to a decrease in maximum specific growth rate of 15 % from 0.74 h(-1) to 0.63 h(-1). Under steady state conditions, a constant cell specific ssDNA formation rate of 0...
June 20, 2017: Journal of Biotechnology
https://www.readbyqxmd.com/read/28645373/strategies-and-methods-of-transcription-coupled-repair-studies-in-vitro-and-in-vivo
#15
Vitaly Epshtein, Venu Kamarthapu, Evgeny Nudler
Transcription-coupled repair (TCR) serves an important role in preserving genome integrity and maintaining fidelity of replication. Coupling transcription to DNA repair requires a coordinated action of several factors, including transcribing RNA polymerase and various transcription modulators and repair proteins. To study TCR in molecular detail, it is important to employ defined protein complexes in vitro and defined genetic backgrounds in vivo. In this chapter, we present methods to interrogate various aspects of TCR at different stages of repair...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28645155/features-of-genomic-organization-in-a-nucleotide-resolution-molecular-model-of-the-escherichia-coli-chromosome
#16
William C Hacker, Shuxiang Li, Adrian H Elcock
We describe structural models of the Escherichia coli chromosome in which the positions of all 4.6 million nucleotides of each DNA strand are resolved. Models consistent with two basic chromosomal orientations, differing in their positioning of the origin of replication, have been constructed. In both types of model, the chromosome is partitioned into plectoneme-abundant and plectoneme-free regions, with plectoneme lengths and branching patterns matching experimental distributions, and with spatial distributions of highly-transcribed chromosomal regions matching recent experimental measurements of the distribution of RNA polymerases...
June 22, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28644990/global-transcriptional-response-of-escherichia-coli-mg1655-cells-exposed-to-the-oxygenated-monoterpenes-citral-and-carvacrol
#17
Beatriz Chueca, Elisa Pérez-Sáez, Rafael Pagán, Diego García-Gonzalo
DNA microarrays were used to study the mechanism of bacterial inactivation by carvacrol and citral. After 10-min treatments of Escherichia coli MG1655 cells with 100 and 50ppm of carvacrol and citral, 76 and 156 genes demonstrated significant transcriptional differences (p≤0.05), respectively. Among the up-regulated genes after carvacrol treatment, we found gene coding for multidrug efflux pumps (acrA, mdtM), genes related to phage shock response (pspA, pspB, pspC, pspD, pspF and pspG), biosynthesis of arginine (argC, argG, artJ), and purine nucleotides (purC, purM)...
June 20, 2017: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/28644830/optimal-chemotactic-responses-in-stochastic-environments
#18
Martin Godány, Bhavin S Khatri, Richard A Goldstein
Although the "adaptive" strategy used by Escherichia coli has dominated our understanding of bacterial chemotaxis, the environmental conditions under which this strategy emerged is still poorly understood. In this work, we study the performance of various chemotactic strategies under a range of stochastic time- and space-varying attractant distributions in silico. We describe a novel "speculator" response in which the bacterium compare the current attractant concentration to the long-term average; if it is higher then they tumble persistently, while if it is lower than the average, bacteria swim away in search of more favorable conditions...
2017: PloS One
https://www.readbyqxmd.com/read/28644760/expression-and-characterization-of-soybean-seed-coat-peroxidase-in-escherichia-coli-bl21-de3
#19
Changqing Liu, Kai Zheng, Ying Xu, Lacmata Tamekou Stephen, Jiming Wang, Hongwei Zhao, Tongqing Yue, Rui Nian, Haibo Zhang, Mo Xian, Huizhou Liu
Soybean seed coat peroxidase(SBP) is a valuable enzyme having a broad variety of applications in analytical chemistry, biochemistry and food processing. In the present study, the sscp gene (Gene ID: 548068) was optimized based on the preferred codon usage of Escherichia coli, synthesized, and expressed in E. coli BL21(DE3). SDS-PAGE and western blot analysis of this expressed protein revealed that its molecular weight is approximately 39 kDa. The effects of induction temperature, concentration of IPTG (isopropyl-β-D-thiogalactoside) and hemin, induction time, expression time were optimized to enhance SBP production with a maximum activity of 11...
June 23, 2017: Preparative Biochemistry & Biotechnology
https://www.readbyqxmd.com/read/28644573/characteristics-of-integrons-and-associated-gene-cassettes-in-antibiotic-resistant-escherichia-coli-isolated-from-free-ranging-food-animals-in-china
#20
Mujeeb Ur Rehman, Hui Zhang, Shucheng Huang, Muhammad Kashif Iqbal, Khalid Mehmood, Houqiang Luo, Jiakui Li
We investigated the occurrence of integrons in antibiotic-resistant Escherichia coli strains isolated from free-ranging food animals, including yaks, piglets, and chickens, in China, and characterized the gene cassettes harbored within the integrons. We examined 432 E. coli strains that exhibited resistance to at least one class of antibiotics. Integrase genes and associated gene cassettes were characterized by polymerase chain reaction (PCR) analysis, restriction fragment-length polymorphism, DNA sequencing, conjugation experiments, and plasmid analysis...
June 23, 2017: Journal of Food Science
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