INCREASING PERMEABILITY OF OUTER MEMBRANE OF E.COLI UNDER ULTRA-LOW FREQUENCY ALTERNATING MAGNETIC FIELD IN THE PRESENCE OF MAGNETIC NANOPARTICLES

2020 ◽  
pp. 90-91
Author(s):  
A. Nikitin ◽  
N. Dagaev ◽  
S. Gribanovsky ◽  
A. Ghigachev ◽  
D. Golovin ◽  
...  
Keyword(s):  
Infectious Diseases ◽  
Outer Membrane ◽  
Rapid Development ◽  
Low Frequency ◽  
Lytic Enzyme ◽  
Gram Negative Bacteria ◽  
Pathogenic Microorganisms ◽  
Gram Negative ◽  
Bacteriolytic Enzymes ◽  
Global Health Problem

Currently, the bacterial etiology infectious diseases still remain a global health problem. Most of them are caused by gram-negative pathogenic microorganisms. The traditional method of infectious diseases treatment is based on the use of antibiotics. However, the rapid development of the resistance of pathogenic microorganisms to existing antibiotics forces to seek alternatives to traditional therapy. One of such alternatives is the therapy with bacteriophage endolysins - bacteriolytic enzymes capable of destroying the bacterial cell wall by hydrolyzing the peptidoglycan. Endolysins are highly specific for certain pathogens. The main limitation of their use towards gram- negative bacteria is the presence of an outer membrane in the latter preventing the penetration of lytic enzyme to its substrate. The effectiveness of endolysin penetration can be increased by destabilizing the outer membrane of gram-negative bacteria

Electrophysiological Characterization of Transport Across Outer Membrane Channels from Gram-Negative Bacteria in Their Native Environment

2019 ◽  
Author(s):  
Jiajun Wang ◽  
Rémi Terrasse ◽  
Jayesh Arun Bafna ◽  
Lorraine Benier ◽  
Mathias Winterhalter
Keyword(s):  
Outer Membrane ◽  
Lipid Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Multi Drug Resistance ◽  
Gram Negative Bacteria ◽  
Membrane Channels ◽  
Gram Negative ◽  
Electrophysiological Characterization

Multi-drug resistance in Gram-negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics, we extract, purify and reconstitute them into artificial planar membranes. To avoid this time-consuming procedure, here we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer which moreover allows also to some extend the characterization of membrane protein channels in their native environment. Two major membrane channels from <i>Escherichia coli</i>, OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution methods, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution. The addition of Enrofloxacin on the LPS side yields somewhat higher association (<i>k<sub>on</sub></i>) and lower dissociation (<i>k<sub>off</sub></i>) rates compared to LPS-free reconstitution. We conclude that using outer membrane vesicles is a fast and easy approach for functional and structural studies of membrane channels in the native membrane.

scholarly journals MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

2021 ◽  
Vol 22 (10) ◽  
pp. 5328
Author(s):  
Miao Ma ◽  
Margaux Lustig ◽  
Michèle Salem ◽  
Dominique Mengin-Lecreulx ◽  
Gilles Phan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Cell Division ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

scholarly journals Shadowing the Actions of a Predator: Backlit Fluorescent Microscopy Reveals Synchronous Nonbinary Septation of Predatory Bdellovibrio inside Prey and Exit through Discrete Bdelloplast Pores

2010 ◽  
Vol 192 (24) ◽  
pp. 6329-6335 ◽  
Author(s):  
A. K. Fenton ◽  
M. Kanna ◽  
R. D. Woods ◽  
S.-I. Aizawa ◽  
R. E. Sockett
Keyword(s):  
Cell Division ◽  
Outer Membrane ◽  
Fluorescent Microscopy ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
Prey Cell ◽  
Gram Negative ◽  
A Genome ◽  
Predatory Bacteria ◽  
First Time

ABSTRACT The Bdellovibrio are miniature “living antibiotic” predatory bacteria which invade, reseal, and digest other larger Gram-negative bacteria, including pathogens. Nutrients for the replication of Bdellovibrio bacteria come entirely from the digestion of the single invaded bacterium, now called a bdelloplast, which is bound by the original prey outer membrane. Bdellovibrio bacteria are efficient digesters of prey cells, yielding on average 4 to 6 progeny from digestion of a single prey cell of a genome size similar to that of the Bdellovibrio cell itself. The developmental intrabacterial cycle of Bdellovibrio is largely unknown and has never been visualized “live.” Using the latest motorized xy stage with a very defined z-axis control and engineered periplasmically fluorescent prey allows, for the first time, accurate return and visualization without prey bleaching of developing Bdellovibrio cells using solely the inner resources of a prey cell over several hours. We show that Bdellovibrio bacteria do not follow the familiar pattern of bacterial cell division by binary fission. Instead, they septate synchronously to produce both odd and even numbers of progeny, even when two separate Bdellovibrio cells have invaded and develop within a single prey bacterium, producing two different amounts of progeny. Evolution of this novel septation pattern, allowing odd progeny yields, allows optimal use of the finite prey cell resources to produce maximal replicated, predatory bacteria. When replication is complete, Bdellovibrio cells exit the exhausted prey and are seen leaving via discrete pores rather than by breakdown of the entire outer membrane of the prey.

scholarly journals PATIENTS' MICROFLORA COMPARATIVE CHARACTERISTICS OF DIFFERENT DEPARTMENTS AT THE NATIONAL HOSPITAL OF PEDIATRICS IN HANOI, VIETNAM

2019 ◽  
pp. 43-48
Author(s):  
L.V. Kataeva ◽  
A.P. Rebeshchenko ◽  
T.F. Stepanova ◽  
O.V. Posoiuznykh ◽  
Le Thanh Hai ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Infectious Diseases ◽  
Hospital Environment ◽  
Clinical Samples ◽  
Gram Negative Bacteria ◽  
National Hospital ◽  
Statistical Research ◽  
Gram Positive ◽  
Gram Negative

We studied the microflora structure and resistance gathered from the biomaterial of patients and the environment objects of various departments at the National hospital of Pediatrics in Hanoi. 140 clinical samples of biomaterials from 74 patients treated in the intensive care unit, the infectious diseases and the gastroenterology departments were studied. A systematic approach including microbiological, epidemiological and statistical research methods was used in carrying out the study. Bacteria of the Enterobacteriaceae family (38.5 per cent) prevailed in the biomaterial of intensive care unit patients. Nonfermentative Gram-negative bacteria (46.5 per cent) occupied the leading positions in the infectious diseases department and Gram-positive bacteria (39.3 per cent) were in the gastroenterology department. Gram-positive flora (60.2 per cent in the intensive care unit and 50.7 per cent in the infectious diseases department) prevailed in the microflora structure gathered from hospital environment objects. We identified the prevalence of bacteria of the genus Enterobacteriaceae and non-fermentative Gram-negative bacteria with a wide spectrum of resistance in the departments of the National Hospital of Pediatrics.

scholarly journals Trans-envelope multidrug efflux pumps of Gram-negative bacteria and their synergism with the outer membrane barrier

2018 ◽  
Vol 169 (7-8) ◽  
pp. 351-356 ◽  
Author(s):  
Helen I. Zgurskaya ◽  
Valentin V. Rybenkov ◽  
Ganesh Krishnamoorthy ◽  
Inga V. Leus
Keyword(s):  
Outer Membrane ◽  
Efflux Pumps ◽  
Gram Negative Bacteria ◽  
Multidrug Efflux ◽  
Gram Negative ◽  
Multidrug Efflux Pumps ◽  
Membrane Barrier
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