Real-time activity assays of β-lactamases in living bacterial cells: application to the inhibition of antibiotic-resistant E. coli strains

2017 ◽  
Vol 13 (11) ◽  
pp. 2323-2327 ◽  
Author(s):  
Ying Ge ◽  
Ya-Jun Zhou ◽  
Ke-Wu Yang ◽  
Yi-Lin Zhang ◽  
Yang Xiang ◽  
...  
Keyword(s):  
Real Time ◽  
Biological Systems ◽  
Bacterial Cells ◽  
Antibiotic Resistant ◽  
Time Activity ◽  
E Coli ◽  
Living Bacteria

A UV-Vis approach is reported for activity assays and inhibition of β-lactamases in complex biological systems of living bacteria.

scholarly journals The Real-Time-Based Assessment of the Microbial Killing by the Antimicrobial Compounds of Neutrophils

2011 ◽  
Vol 11 ◽  
pp. 2382-2390 ◽  
Author(s):  
J. T. Atosuo ◽  
E.-M. Lilius
Keyword(s):  
Real Time ◽  
Antimicrobial Agents ◽  
Hypochlorous Acid ◽  
Bacterial Cells ◽  
Photorhabdus Luminescens ◽  
Bacterial Luciferase ◽  
E Coli ◽  
High Concentrations ◽  
Time Basis ◽  
K 12

A recombinantEscherichia coliK-12 strain, transformed with a modified bacterial luciferase gene (luxABCDE) fromPhotorhabdus luminescens, was constructed in order to monitor the activity of various antimicrobial agents on a real-time basis. ThisE. coli-lux emitted, without any addition of substrate, constitutive bioluminescence (BL), which correlated to the number of viable bacterial cells. The decrease in BL signal correlated to the number of killed bacterial cells. Antimicrobial activity of hydrogen peroxide (H2O2) and myeloperoxidase (MPO) was assessed. In high concentrations, H2O2alone had a bacteriocidic function and MPO enhanced this killing by forming hypochlorous acid (HOCl). Taurine, the known HOCl scavenger, blocked the killing by MPO. WhenE. coli-lux was incubated with neutrophils, similar killing kinetics was recorded as in H2O2/MPO experiments. The opsonization of bacteria enhanced the killing, and the maximum rate of the MPO release from lysosomes coincided with the onset of the killing.

scholarly journals Metabolic Flux Analysis of Catechin Biosynthesis Pathways Using Nanosensor

Antioxidants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 288
Author(s):  
Habiba Kausar ◽  
Ghazala Ambrin ◽  
Mohammad K. Okla ◽  
Walid Soufan ◽  
Abdullah A. Al-Ghamdi ◽  
...  
Keyword(s):  
Metabolic Engineering ◽  
Real Time ◽  
Metabolic Flux Analysis ◽  
Metabolic Flux ◽  
Regulatory Element ◽  
Flux Analysis ◽  
Bacterial Cells ◽  
Biosynthesis Pathway ◽  
Real Time Monitoring ◽  
E Coli

(+)-Catechin is an important antioxidant of green tea (Camelia sinensis (L.) O. Kuntze). Catechin is known for its positive role in anticancerous activity, extracellular matrix degradation, cell death regulation, diabetes, and other related disorders. As a result of enormous interest in and great demand for catechin, its biosynthesis using metabolic engineering has become the subject of concentrated research with the aim of enhancing (+)-catechin production. Metabolic flux is an essential concept in the practice of metabolic engineering as it helps in the identification of the regulatory element of a biosynthetic pathway. In the present study, an attempt was made to analyze the metabolic flux of the (+)-catechin biosynthesis pathway in order to decipher the regulatory element of this pathway. Firstly, a genetically encoded fluorescence resonance energy transfer (FRET)-based nanosensor (FLIP-Cat, fluorescence indicator protein for (+)-catechin) was developed for real-time monitoring of (+)-catechin flux. In vitro characterization of the purified protein of the nanosensor showed that the nanosensor was pH stable and (+)-catechin specific. Its calculated Kd was 139 µM. The nanosensor also performed real-time monitoring of (+)-catechin in bacterial cells. In the second step of this study, an entire (+)-catechin biosynthesis pathway was constructed and expressed in E. coli in two sets of plasmid constructs: pET26b-PT7-rbs-PAL-PT7-rbs-4CL-PT7-rbs-CHS-PT7-rbs-CHI and pET26b-T7-rbs-F3H-PT7-rbs- DFR-PT7-rbs-LCR. The E. coli harboring the FLIP-Cat was transformed with these plasmid constructs. The metabolic flux analysis of (+)-catechin was carried out using the FLIP-Cat. The FLIP-Cat successfully monitored the flux of catechin after adding tyrosine, 4-coumaric acid, 4-coumaroyl CoA, naringenin chalcone, naringenin, dihydroquercetin, and leucocyanidin, individually, with the bacterial cells expressing the nanosensor as well as the genes of the (+)-catechin biosynthesis pathway. Dihydroflavonol reductase (DFR) was identified as the main regulatory element of the (+)-catechin biosynthesis pathway. Information about this regulatory element of the (+)-catechin biosynthesis pathway can be used for manipulating the (+)-catechin biosynthesis pathway using a metabolic engineering approach to enhance production of (+)-catechin.

scholarly journals Antibacterial Activity of Synthetic Cationic Iron Porphyrins

Antioxidants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 972
Author(s):  
Artak Tovmasyan ◽  
Ines Batinic-Haberle ◽  
Ludmil Benov
Keyword(s):  
Bactericidal Activity ◽  
Protoporphyrin Ix ◽  
Laboratory Animals ◽  
Bacterial Cells ◽  
Decomposition Products ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Resistant Strains ◽  
Positively Charged ◽  
New Strategies

Widespread antibiotic resistance demands new strategies for fighting infections. Porphyrin-based compounds were long ago introduced as photosensitizers for photodynamic therapy, but light-independent antimicrobial activity of such compounds has not been systematically explored. The results of this study demonstrate that synthetic cationic amphiphilic iron N-alkylpyridylporphyrins exert strong bactericidal action at concentrations as low as 5 μM. Iron porphyrin, FeTnHex-2-PyP, which is well tolerated by laboratory animals, efficiently killed Gram-negative and Gram-positive microorganisms. Its bactericidal activity was oxygen-independent and was controlled by the lipophilicity and accumulation of the compound in bacterial cells. Such behavior is in contrast with the anionic gallium protoporphyrin IX, whose efficacy depends on cellular heme uptake systems. Under aerobic conditions, however, the activity of FeTnHex-2-PyP was limited by its destruction due to redox-cycling. Neither iron released from the Fe-porphyrin nor other decomposition products were the cause of the bactericidal activity. FeTnHex-2-PyP was as efficient against antibiotic-sensitive E. coli and S. aureus as against their antibiotic-resistant counterparts. Our data demonstrate that development of amphiphilic, positively charged metalloporphyrins might be a promising approach in the introduction of new weapons against antibiotic-resistant strains.

Real-time PCR and enzyme-linked fluorescent assay methods for detecting Shiga-toxin-producingEscherichia coliin mincemeat samples

2007 ◽  
Vol 53 (3) ◽  
pp. 337-342 ◽  
Author(s):  
A. Stefan ◽  
S. Scaramagli ◽  
R. Bergami ◽  
C. Mazzini ◽  
M. Barbanera ◽  
...  
Keyword(s):  
Real Time ◽  
Shiga Toxin ◽  
Real Time Pcr ◽  
Central Italy ◽  
Health Concern ◽  
Bacterial Cells ◽  
Fluorescent Assay ◽  
Point Of Sale ◽  
E Coli ◽  
Assay Methods

This work aimed to compare real-time polymerase chain reaction (PCR) with the commercially available enzyme-linked fluorescent assay (ELFA) VIDAS ECOLI O157™ for detecting Escherichia coli O157 in mincemeat. In addition, a PCR-based survey on Shiga-toxin-producing E. coli (STEC) in mincemeat collected in Italy is presented. Real-time PCR assays targeting the stx genes and a specific STEC O157 sequence (SILO157, a small inserted locus of STEC O157) were tested for their sensitivity on spiked mincemeat samples. After overnight enrichment, the presence of STEC cells could be clearly determined in the 25 g samples containing 10 bacterial cells, while the addition of five bacteria provided equivocal PCR results with Ct values very close to or above the threshold of 40. The PCR tests proved to be more sensitive than the ELFA-VIDAS ECOLI O157™, whose detection level started from 50 bacterial cells/25 g of mincemeat. The occurrence of STEC in 106 mincemeat (bovine, veal) samples collected from September to November 2004 at five different points of sale in Italy (one point of sale in Arezzo, Tuscany, central Italy, two in Mantova, Lombardy, Northern Italy, and two in Bologna, Emilia-Romagna, upper-central Italy) was less than 1%. Contamination by the main STEC O-serogroups representing a major public health concern, including O26, O91, O111, O145, and O157, was not detected. This survey indicates that STEC present in these samples are probably not associated with pathogenesis in humans.

scholarly journals Rapid and Accurate Detection of Bacteriophage Activity againstEscherichia coliO157:H7 by Propidium Monoazide Real-Time PCR

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Hui Liu ◽  
Yan D. Niu ◽  
Jinquan Li ◽  
Kim Stanford ◽  
Tim A. McAllister
Keyword(s):  
Cell Surface ◽  
Real Time ◽  
Quantitative Polymerase Chain Reaction ◽  
Extracellular Dna ◽  
Bacterial Cells ◽  
Propidium Monoazide ◽  
Direct Plating ◽  
E Coli ◽  
Polymerase Chain ◽  
Phage Activity

Conventional methods to determine the efficacy of bacteriophage (phage) for biocontrol ofE. colirequire several days, due to the need to culture bacteria. Furthermore, cell surface-attached phage particles may lyse bacterial cells during experiments, leading to an overestimation of phage activity. DNA-based real-time quantitative polymerase chain reaction (qPCR) is a fast, sensitive, and highly specific means of enumerating pathogens. However, qPCR may underestimate phage activity due to its inability to distinguish viable from nonviable cells. In this study, we evaluated the suitability of propidium monoazide (PMA), a microbial membrane-impermeable dye that inhibits amplification of extracellular DNA and DNA within dead or membrane-compromised cells as a means of using qPCR to identify only intactE. colicells that survive phage exposure.Escherichia coliO157:H7 strain R508N and 4 phages (T5-like, T1-like, T4-like, and O1-like) were studied. Results compared PMA-qPCR and direct plating and confirmed that PMA could successfully inhibit amplification of DNA from compromised/damaged cellsE. coliO157:H7. Compared to PMA-qPCR, direct plating overestimated (P< 0.01) phage efficacy as cell surface-attached phage particles lysedE. coliO157:H7 during the plating process. Treatment of samples with PMA in combination with qPCR can therefore be considered beneficial when assessing the efficacy of bacteriophage for biocontrol ofE. coliO157:H7.

scholarly journals Surface Modification by Media Organics Reduces the Bacterio-toxicity of Cupric Oxide Nanoparticle against Escherichia coli

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ruchira Chakraborty ◽  
Tarakdas Basu
Keyword(s):  
Surface Modification ◽  
Nutrient Medium ◽  
Cupric Oxide ◽  
Copper Oxide Nanoparticles ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Bactericidal Effects ◽  
Oxide Nanoparticle

Abstract Prevalence of antibiotic-resistant bacteria demands alternatives to antibiotics. Copper-based nanoparticles with a high antibacterial property may be a solution to the problem. It is, therefore, important to understand the mode of antibacterial action of the nanoparticles (NPs). Despite reports on induction of reactive oxygen species (ROS) in bacteria by copper and copper-oxide nanoparticles and involvement of such ROS in cell killing, it is still unclear (a) if surface modification of the nanoparticles by media organics has any role on their antibacterial potency and (b) whether the bactericidal effects of these NPs are ‘particle-specific’ or ‘ion-specific’ in nature. We address these issues for cupric oxide nanoparticle (CuO-NP) in this study. Instead of nutrient medium, when E. coli bacterial cells were suspended in saline (0.9% NaCl), CuO-NP had a more anti-bacterial effect, with MBC (minimum bactericidal concentration) value of 6 µg/mL, than in nutrient medium with MBC value of 160 µg/mL. Moreover, the lysine-modified CuO-NP in saline had MBC at 130 µg/mL. Thus, unmodified CuO-NP was more efficient killer than modified one. Our finding further revealed that in saline;CuO-NP had ‘particle-specific’ antibacterial effect through generation of ROS and consequent oxidative damage by lipid peroxidation, protein oxidation and DNA degradation in cells.

Real-time activity monitoring of New Delhi metallo-β-lactamase-1 in living bacterial cells by UV-Vis spectroscopy

2017 ◽  
Vol 53 (57) ◽  
pp. 8014-8017 ◽  
Author(s):  
Ke-Wu Yang ◽  
Yajun Zhou ◽  
Ying Ge ◽  
Yuejuan Zhang
Keyword(s):  
Real Time ◽  
Activity Monitoring ◽  
New Delhi ◽  
Bacterial Cells ◽  
Time Activity ◽  
Vis Spectroscopy

A novel UV-Vis method for monitoring the reactions of the β-lactam antibiotics inside living bacterial cells.

Mechanisms involved in effects of antimicrobial peptides, bactenectins ChBac3.4, ChBac5, and mini-ChBac7.5Nb, on bacterial cells

2017 ◽  
pp. 43-50
Author(s):  
О.В. Шамова ◽  
М.С. Жаркова ◽  
П.М. Копейкин ◽  
Д.С. Орлов ◽  
Е.А. Корнева
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Innate Immunity ◽  
Infectious Diseases ◽  
Metabolic Activity ◽  
Capra Hircus ◽  
Bacterial Cells ◽  
Antibiotic Resistant ◽  
Resistant Strains

Антимикробные пептиды (АМП) системы врожденного иммунитета - соединения, играющие важную роль в патогенезе инфекционных заболеваний, так как обладают свойством инактивировать широкий спектр патогенных бактерий, обеспечивая противомикробную защиту живых организмов. В настоящее время АМП рассматриваются как потенциальные соединения-корректоры инфекционной патологии, вызываемой антибиотикорезистентными бактериями (АБР). Цель данной работы состояла в изученим механизмов антибактериального действия трех пептидов, принадлежащих к семейству бактенецинов - ChBac3.4, ChBac5 и mini-ChBac7.5Nb. Эти химически синтезированные пептиды являются аналогами природных пролин-богатых АМП, обнаруженных в лейкоцитах домашней козы Capra hircus и проявляющих высокую антимикробную активность, в том числе и в отношении грамотрицательных АБР. Методы. Минимальные ингибирующие и минимальные бактерицидные концентрации пептидов (МИК и МБК) определяли методом серийных разведений в жидкой питательной среде с последующим высевом на плотную питательную среду. Эффекты пептидов на проницаемость цитоплазматической мембраны бактерий для хромогенного маркера исследовали с использованием генетически модифицированного штамма Escherichia coli ML35p. Действие бактенецинов на метаболическую активность бактерий изучали с применением маркера резазурина. Результаты. Показано, что все исследованные пептиды проявляют высокую антимикробную активность в отношении Escherichia coli ML35p и антибиотикоустойчивых штаммов Escherichia coli ESBL и Acinetobacter baumannii in vitro, но их действие на бактериальные клетки разное. Использован комплекс методик, позволяющих наблюдать в режиме реального времени динамику действия бактенецинов в различных концентрациях (включая их МИК и МБК) на барьерную функцию цитоплазматической мембраны и на интенсивность метаболизма бактериальных клеток, что дало возможность выявить различия в характере воздействия бактенецинов, отличающихся по структуре молекулы, на исследуемые микроорганизмы. Установлено, что действие каждого из трех исследованных бактенецинов в бактерицидных концентрациях отличается по эффективности нарушения целостности бактериальных мембран и в скорости подавления метаболизма клеток. Заключение. Полученная информация дополнит существующие фундаментальные представления о механизмах действия пролин-богатых пептидов врожденного иммунитета, а также послужит основой для биотехнологических исследований, направленных на разработку на базе этих соединений новых антибиотических препаратов для коррекции инфекционных заболеваний, вызываемых АБР и являющимися причинами тяжелых внутрибольничных инфекций. Antimicrobial peptides (AMPs) of the innate immunity are compounds that play an important role in pathogenesis of infectious diseases due to their ability to inactivate a broad array of pathogenic bacteria, thereby providing anti-microbial host defense. AMPs are currently considered promising compounds for treatment of infectious diseases caused by antibiotic-resistant bacteria. The aim of this study was to investigate molecular mechanisms of the antibacterial action of three peptides from the bactenecin family, ChBac3.4, ChBac5, and mini-ChBac7.5Nb. These chemically synthesized peptides are analogues of natural proline-rich AMPs previously discovered by the authors of the present study in leukocytes of the domestic goat, Capra hircus. These peptides exhibit a high antimicrobial activity, in particular, against antibiotic-resistant gram-negative bacteria. Methods. Minimum inhibitory and minimum bactericidal concentrations of the peptides (MIC and MBC) were determined using the broth microdilution assay followed by subculturing on agar plates. Effects of the AMPs on bacterial cytoplasmic membrane permeability for a chromogenic marker were explored using a genetically modified strain, Escherichia coli ML35p. The effect of bactenecins on bacterial metabolic activity was studied using a resazurin marker. Results. All the studied peptides showed a high in vitro antimicrobial activity against Escherichia coli ML35p and antibiotic-resistant strains, Escherichia coli ESBL and Acinetobacter baumannii, but differed in features of their action on bacterial cells. The used combination of techniques allowed the real-time monitoring of effects of bactenecin at different concentrations (including their MIC and MBC) on the cell membrane barrier function and metabolic activity of bacteria. The differences in effects of these three structurally different bactenecins on the studied microorganisms implied that these peptides at bactericidal concentrations differed in their capability for disintegrating bacterial cell membranes and rate of inhibiting bacterial metabolism. Conclusion. The obtained information will supplement the existing basic concepts on mechanisms involved in effects of proline-rich peptides of the innate immunity. This information will also stimulate biotechnological research aimed at development of new antibiotics for treatment of infectious diseases, such as severe in-hospital infections, caused by antibiotic-resistant strains.

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