scholarly journals In Situ Characterization of Differences in the Viscoelastic Response of Individual Gram-Negative and Gram-Positive Bacterial Cells

2009 ◽  
Vol 191 (17) ◽  
pp. 5518-5525 ◽  
Author(s):  
Virginia Vadillo-Rodriguez ◽  
Sarah R. Schooling ◽  
John R. Dutcher
Keyword(s):  
Viscoelastic Properties ◽  
Cell Envelope ◽  
Outer Membrane Proteins ◽  
Elastic Response ◽  
Bacterial Cells ◽  
Structure Property ◽  
Gram Positive ◽  
Gram Negative ◽  
Structure Property Relationships ◽  
Cell Envelopes

ABSTRACT We used a novel atomic force microscopy (AFM)-based technique to compare the local viscoelastic properties of individual gram-negative (Escherichia coli) and gram-positive (Bacillus subtilis) bacterial cells. We found that the viscoelastic properties of the bacterial cells are well described by a three-component mechanical model that combines an instantaneous elastic response and a delayed elastic response. These experiments have allowed us to investigate the relationship between the viscoelastic properties and the structure and composition of the cell envelope. In addition, this is the first report in which the mechanical role of Lpp, the major peptidoglycan-associated lipoprotein and one of the most abundant outer membrane proteins in E. coli cells, has been quantified. We expect that our findings will be helpful in increasing the understanding of the structure-property relationships of bacterial cell envelopes.

scholarly journals Influence of molecular structure on the antimicrobial function of phenylenevinylene conjugated oligoelectrolytes

2016 ◽  
Vol 7 (9) ◽  
pp. 5714-5722 ◽  
Author(s):  
Hengjing Yan ◽  
Zachary D. Rengert ◽  
Alexander W. Thomas ◽  
Carolin Rehermann ◽  
Jamie Hinks ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Structure Property ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Structure Property Relationships ◽  
Antimicrobial Function

Structure/property relationships were obtained to understand the antimicrobial function of conjugated oligoelectrolytes toward Gram-negative and Gram-positive bacteria.

scholarly journals Long-distance electron transfer in a filamentous Gram-positive bacterium

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yonggang Yang ◽  
Zegao Wang ◽  
Cuifen Gan ◽  
Lasse Hyldgaard Klausen ◽  
Robin Bonné ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Microbial Fuel Cells ◽  
Extracellular Electron Transfer ◽  
Gram Negative Bacteria ◽  
Positive Bacterium ◽  
Long Distance ◽  
Gram Positive ◽  
Gram Negative ◽  
Force Microscopy ◽  
Cell Envelopes

AbstractLong-distance extracellular electron transfer has been observed in Gram-negative bacteria and plays roles in both natural and engineering processes. The electron transfer can be mediated by conductive protein appendages (in short unicellular bacteria such as Geobacter species) or by conductive cell envelopes (in filamentous multicellular cable bacteria). Here we show that Lysinibacillus varians GY32, a filamentous unicellular Gram-positive bacterium, is capable of bidirectional extracellular electron transfer. In microbial fuel cells, L. varians can form centimetre-range conductive cellular networks and, when grown on graphite electrodes, the cells can reach a remarkable length of 1.08 mm. Atomic force microscopy and microelectrode analyses suggest that the conductivity is linked to pili-like protein appendages. Our results show that long-distance electron transfer is not limited to Gram-negative bacteria.

scholarly journals Evaluating Flinders Technology Associates card for transporting bacterial isolates and retrieval of bacterial DNA after various storage conditions

2020 ◽  
Vol 13 (10) ◽  
pp. 2243-2251
Author(s):  
Azhar G. Shalaby ◽  
Neveen R. Bakry ◽  
Abeer A. E. Mohamed ◽  
Ashraf A. Khalil
Keyword(s):  
Nucleic Acid ◽  
Bacterial Species ◽  
Storage Conditions ◽  
Animal Origin ◽  
Cell Detection ◽  
Bacterial Cells ◽  
Gram Positive ◽  
Bacterial Dna ◽  
Gram Negative ◽  
Fta Cards

Background and Aim: Flinders Technology Associates (FTA) cards simplify sample storage, transport, and extraction by reducing cost and time for diagnosis. This study evaluated the FTA suitability for safe transport and storage of Gram-positive and Gram-negative bacterial cells of animal origin on its liquid culture form and from organ impression smears (tissues) under the same routine condition of microbiological laboratory along with detecting their nucleic acid over different storage conditions. Materials and Methods: Increase in bacterial count from 104 to 107 (colony-forming units/mL) of 78 isolates representing seven bacterial species was applied onto cards. FTA cards were grouped and inoculated by these bacteria and then stored at different conditions of 24-27°C, 4°C, and –20°C for 24 h, for 2 weeks, for 1 and 3 month storage, respectively. Bacteriological examination was done, after which bacterial DNA was identified using specific primers for each bacterial type and detected by polymerase chain reaction (PCR). Results: The total percentage of recovered bacteria from FTA cards was 66.7% at 24-27–C for 24 h, the detection limit was 100% in Gram-positive species, while it was 57.4% in Gram-negative ones. Regarding viable cell detection from organ impression smears, it was successful under the previous conditions. No live bacterial cells were observed by bacteriological isolation rather than only at 24-27°C for 24 h storage. All bacterial DNA were sufficiently confirmed by the PCR technique at different conditions. Conclusion: Overall, the FTA card method was observed to be a valid tool for nucleic acid purification for bacteria of animal origin in the form of culture or organ smears regardless of its Gram type and is used for a short time only 24 h for storage and transport of live bacteria specifically Gram-positive type. Moreover, the bacterial nucleic acid was intact after storage in –20°C for 3 months and was PCR amplifiable.

scholarly journals TSPphg Lysin from the Extremophilic Thermus Bacteriophage TSP4 as a Potential Antimicrobial Agent against Both Gram-Negative and Gram-Positive Pathogenic Bacteria

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 192 ◽  
Author(s):  
Feng Wang ◽  
Xinyu Ji ◽  
Qiupeng Li ◽  
Guanling Zhang ◽  
Jiani Peng ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Infection Model ◽  
Bacterial Cells ◽  
Skin Damage ◽  
Gram Positive ◽  
Antibiotic Resistant ◽  
Gram Negative

New strategies against antibiotic-resistant bacterial pathogens are urgently needed but are not within reach. Here, we present in vitro and in vivo antimicrobial activity of TSPphg, a novel phage lysin identified from extremophilic Thermus phage TSP4 by sequencing its whole genome. By breaking down the bacterial cells, TSPphg is able to cause bacteria destruction and has shown bactericidal activity against both Gram-negative and Gram-positive pathogenic bacteria, especially antibiotic-resistant strains of Klebsiella pneumoniae, in which the complete elimination and highest reduction in bacterial counts by greater than 6 logs were observed upon 50 μg/mL TSPphg treatment at 37 °C for 1 h. A murine skin infection model further confirmed the in vivo efficacy of TSPphg in removing a highly dangerous and multidrug-resistant Staphylococcus aureus from skin damage and in accelerating wound closure. Together, our findings may offer a therapeutic alternative to help fight bacterial infections in the current age of mounting antibiotic resistance, and to shed light on bacteriophage-based strategies to develop novel anti-infectives.

scholarly journals Bacterial Cellulose Containing Combinations of Antimicrobial Peptides with Various QQ Enzymes as a Prototype of an “Enhanced Antibacterial” Dressing: In Silico and In Vitro Data

Pharmaceutics ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1155
Author(s):  
Aysel Aslanli ◽  
Ilya Lyagin ◽  
Nikolay Stepanov ◽  
Denis Presnov ◽  
Elena Efremenko
Keyword(s):  
Antimicrobial Peptides ◽  
Bacterial Cellulose ◽  
In Silico ◽  
Antimicrobial Agents ◽  
Penicillin Acylase ◽  
Signal Molecules ◽  
Bacterial Cells ◽  
Gram Positive ◽  
Gram Negative

To improve the action of already in use antibiotics or new antimicrobial agents against different bacteria, the development of effective combinations of antimicrobial peptides (AMPs) with enzymes that can quench the quorum (QQ) sensing of bacterial cells was undertaken. Enzymes hydrolyzing N-acyl homoserine lactones (AHLs) and peptides that are signal molecules of Gram-negative and Gram-positive bacterial cells, respectively, were estimated as “partners” for antibiotics and antimicrobial peptides in newly designed antimicrobial–enzymatic combinations. The molecular docking of six antimicrobial agents to the surface of 10 different QQ enzyme molecules was simulated in silico. This made it possible to choose the best variants among the target combinations. Further, bacterial cellulose (BC) was applied as a carrier for uploading such combinations to generally compose prototypes of effective dressing materials with morphology, providing good absorbance. The in vitro analysis of antibacterial activity of prepared BC samples confirmed the significantly enhanced efficiency of the action of AMPs (including polymyxin B and colistin, which are antibiotics of last resort) in combination with AHL-hydrolyzing enzymes (penicillin acylase and His6-tagged organophosphorus hydrolase) against both Gram-negative and Gram-positive cells.

scholarly journals THE PRODUCTION OF BACTERICIDAL SUBSTANCES BY AEROBIC SPORULATING BACILLI

1941 ◽  
Vol 73 (5) ◽  
pp. 629-640 ◽  
Author(s):  
René J. Dubos ◽  
Rollin D. Hotchkiss
Keyword(s):  
Insoluble Fraction ◽  
Physiological Effect ◽  
Antagonistic Activity ◽  
Bacterial Cells ◽  
Animal Tissues ◽  
Gram Positive ◽  
Culture Collections ◽  
Gram Negative

Several species of aerobic sporulating bacilli recently isolated from soil, sewage, manure, and cheese, as well as authentic strains obtained from type culture collections, have been found to exhibit antagonistic activity against unrelated microorganisms. Cultures of these aerobic sporulating bacilli yield an alcohol-soluble, water-insoluble fraction,—tyrothricin,—which is bactericidal for most Gram-positive and Gram-negative microbial species. Two different crystalline products have been separated from tyrothricin. One, which may be called tyrocidine, is bactericidal in vitro for both Gram-positive and Gram-negative species; the other substance, gramicidin, is effective only against Gram-positive microorganisms. In general, tyrocidine behaves like a protoplasmic poison and like other antiseptics, loses much of its activity in the presence of animal tissues. Gramicidin on the contrary exerts a much more subtle physiological effect on the susceptible bacterial cells and, when applied locally at the site of the infection, retains in vivo a striking activity against Gram-positive microorganisms.

COMPARATIVE STUDIES ON THE GROWTH OF MYXOBACTERIA ON BACTERIAL SUSPENSIONS

1963 ◽  
Vol 9 (4) ◽  
pp. 577-584 ◽  
Author(s):  
B. Kletter ◽  
Y. Henis
Keyword(s):  
Growth Medium ◽  
Test Organism ◽  
Growth Media ◽  
Multiplication Rate ◽  
Bacterial Cells ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Negative Organisms ◽  
Myxococcus Virescens ◽  
Number Of Bacteria

The growth of Myxococcus fulvus and Myxococcus virescens on a number of bacteria was followed in a liquid medium. Multiplication of the myxobacteria was accompanied by their adsorption on the bacterial cells, by their coagglutination, and by their adsorption on the glass surface of the culture flask. Lysis of the agglutinated bacterial cells and release of their proteins to the growth medium took place prior to an increase in the lytic activity of the growth medium towards the tested bacteria. Soluble proteins reached a higher level in media containing Gram-negative than in those containing the Gram-positive organisms. No difference was observed in the multiplication rate, sporulation, or pigmentation of the myxobacteria tested, when grown on either Gram-positive or Gram-negative organisms. Using Staphylococcus aureus as a test organism, no antibiotic activity in any of the growth media could be detected.

Probing interaction of Gram-positive and Gram-negative bacterial cells with ZnO nanorods

2013 ◽  
Vol 33 (3) ◽  
pp. 1247-1253 ◽  
Author(s):  
Aanchal Jain ◽  
Richa Bhargava ◽  
Pankaj Poddar
Keyword(s):  
Zno Nanorods ◽  
Bacterial Cells ◽  
Gram Positive ◽  
Gram Negative

scholarly journals Optotracing for selective fluorescence-based detection, visualization and quantification of live S. aureus in real-time

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Karen Butina ◽  
Ana Tomac ◽  
Ferdinand X. Choong ◽  
Hamid Shirani ◽  
K. Peter R. Nilsson ◽  
...  
Keyword(s):  
Real Time ◽  
Hydrophobic Interactions ◽  
Cell Envelope ◽  
Super Resolution ◽  
Bacterial Cells ◽  
Gram Negative ◽  
Donor Acceptor ◽  
Basic And Applied Research ◽  
Opportunistic Human Pathogen ◽  
Tracer Molecules

AbstractMethods for bacterial detection are needed to advance the infection research and diagnostics. Based on conformation-sensitive fluorescent tracer molecules, optotracing was recently established for dynamic detection and visualization of structural amyloids and polysaccharides in the biofilm matrix of gram-negative bacteria. Here, we extend the use of optotracing for detection of gram-positive bacteria, focussing on the clinically relevant opportunistic human pathogen Staphylococcus aureus. We identify a donor-acceptor-donor-type optotracer, whose binding-induced fluorescence enables real-time detection, quantification, and visualization of S. aureus in monoculture and when mixed with gram-negative Salmonella Enteritidis. An algorithm-based automated high-throughput screen of 1920 S. aureus transposon mutants recognized the cell envelope as the binding target, which was corroborated by super-resolution microscopy of bacterial cells and spectroscopic analysis of purified cell wall components. The binding event was essentially governed by hydrophobic interactions, which permitted custom-designed tuning of the binding selectivity towards S. aureus versus Enterococcus faecalis by appropriate selection of buffer conditions. Collectively this work demonstrates optotracing as an enabling technology relevant for any field of basic and applied research, where visualization and detection of S. aureus is needed.

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