scholarly journals Uncharacterized bacterial structures revealed by electron cryotomography

2017 ◽  
Author(s):  
Megan J. Dobro ◽  
Catherine M. Oikonomou ◽  
Aidan Piper ◽  
John Cohen ◽  
Kylie Guo ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Structural Complexity ◽  
Species Range ◽  
Bacterial Cells ◽  
Native Structure ◽  
Intact Cells ◽  
Macromolecular Complexes ◽  
Summary Statement ◽  
Electron Cryotomography ◽  
Novel Structures

SUMMARY STATEMENTHere we present a survey of previously uncharacterized structures we have observed in bacterial cells by electron cryotomography, in the hopes of spurring their identification and study.ABSTRACTElectron cryotomography (ECT) can reveal the native structure and arrangement of macromolecular complexes inside intact cells. This technique has greatly advanced our understanding of the ultrastructure of bacterial cells. Rather than undifferentiated bags of enzymes, we now view bacteria as structurally complex assemblies of macromolecular machines. To date, our group has applied ECT to nearly 90 different bacterial species, collecting more than 15,000 cryotomograms. In addition to known structures, we have observed several, to our knowledge, uncharacterized features in these tomograms. Some are completely novel structures; others expand the features or species range of known structure types. Here we present a survey of these uncharacterized bacterial structures in the hopes of accelerating their identification and study, and furthering our understanding of the structural complexity of bacterial cells.

scholarly journals Uncharacterized Bacterial Structures Revealed by Electron Cryotomography

2017 ◽  
Vol 199 (17) ◽  
Author(s):  
Megan J. Dobro ◽  
Catherine M. Oikonomou ◽  
Aidan Piper ◽  
John Cohen ◽  
Kylie Guo ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Structural Complexity ◽  
Species Range ◽  
Bacterial Cells ◽  
Native Structure ◽  
Intact Cells ◽  
Macromolecular Complexes ◽  
Electron Cryotomography ◽  
Novel Structures

ABSTRACT Electron cryotomography (ECT) can reveal the native structure and arrangement of macromolecular complexes inside intact cells. This technique has greatly advanced our understanding of the ultrastructure of bacterial cells. We now view bacteria as structurally complex assemblies of macromolecular machines rather than as undifferentiated bags of enzymes. To date, our group has applied ECT to nearly 90 different bacterial species, collecting more than 15,000 cryotomograms. In addition to known structures, we have observed, to our knowledge, several uncharacterized features in these tomograms. Some are completely novel structures; others expand the features or species range of known structure types. Here, we present a survey of these uncharacterized bacterial structures in the hopes of accelerating their identification and study, and furthering our understanding of the structural complexity of bacterial cells. IMPORTANCE Bacteria are more structurally complex than is commonly appreciated. Here we present a survey of previously uncharacterized structures that we observed in bacterial cells by electron cryotomography, structures that will initiate new lines of research investigating their identities and roles.

Modulation of Gut Microbiota through Dietary Phytochemicals as a Novel Anti-infective Strategy

2020 ◽  
Vol 17 (4) ◽  
pp. 498-506 ◽  
Author(s):  
Pavan K. Mujawdiya ◽  
Suman Kapur
Keyword(s):  
Microbial Community ◽  
Quorum Sensing ◽  
Population Density ◽  
Gut Microbiota ◽  
Biofilm Formation ◽  
Chemical Interaction ◽  
Bacterial Species ◽  
Critical Role ◽  
Bacterial Cells ◽  
Gut Microbes

: Quorum Sensing (QS) is a phenomenon in which bacterial cells communicate with each other with the help of several low molecular weight compounds. QS is largely dependent on population density, and it triggers when the concentration of quorum sensing molecules accumulate in the environment and crosses a particular threshold. Once a certain population density is achieved and the concentration of molecules crosses a threshold, the bacterial cells show a collective behavior in response to various chemical stimuli referred to as “auto-inducers”. The QS signaling is crucial for several phenotypic characteristics responsible for bacterial survival such as motility, virulence, and biofilm formation. Biofilm formation is also responsible for making bacterial cells resistant to antibiotics. : The human gut is home to trillions of bacterial cells collectively called “gut microbiota” or “gut microbes”. Gut microbes are a consortium of more than 15,000 bacterial species and play a very crucial role in several body functions such as metabolism, development and maturation of the immune system, and the synthesis of several essential vitamins. Due to its critical role in shaping human survival and its modulating impact on body metabolisms, the gut microbial community has been referred to as “the forgotten organ” by O`Hara et al. (2006) [1]. Several studies have demonstrated that chemical interaction between the members of bacterial cells in the gut is responsible for shaping the overall microbial community. : Recent advances in phytochemical research have generated a lot of interest in finding new, effective, and safer alternatives to modern chemical-based medicines. In the context of antimicrobial research various plant extracts have been identified with Quorum Sensing Inhibitory (QSI) activities among bacterial cells. This review focuses on the mechanism of quorum sensing and quorum sensing inhibitors isolated from natural sources.

scholarly journals Bacteria in the global atmosphere – Part 2: Modeling of emissions and transport between different ecosystems

2009 ◽  
Vol 9 (23) ◽  
pp. 9281-9297 ◽  
Author(s):  
S. M. Burrows ◽  
T. Butler ◽  
P. Jöckel ◽  
H. Tost ◽  
A. Kerkweg ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Residence Time ◽  
General Circulation ◽  
Bacterial Species ◽  
Circulation Model ◽  
Cloud Condensation Nucleus ◽  
Cloud Formation ◽  
Emission Region ◽  
Culturable Bacteria ◽  
Bacterial Cells

Abstract. Bacteria are constantly being transported through the atmosphere, which may have implications for human health, agriculture, cloud formation, and the dispersal of bacterial species. We simulate the global transport of bacteria, represented as 1 μm and 3 μm diameter spherical solid particle tracers in a general circulation model. We investigate factors influencing residence time and distribution of the particles, including emission region, cloud condensation nucleus activity and removal by ice-phase precipitation. The global distribution depends strongly on the assumptions made about uptake into cloud droplets and ice. The transport is also affected, to a lesser extent, by the emission region, particulate diameter, and season. We find that the seasonal variation in atmospheric residence time is insufficient to explain by itself the observed seasonal variation in concentrations of particulate airborne culturable bacteria, indicating that this variability is mainly driven by seasonal variations in culturability and/or emission strength. We examine the potential for exchange of bacteria between ecosystems and obtain rough estimates of the flux from each ecosystem by using a maximum likelihood estimation technique, together with a new compilation of available observations described in a companion paper. Globally, we estimate the total emissions of bacteria-containing particles to the atmosphere to be 7.6×1023–3.5×1024 a−1, originating mainly from grasslands, shrubs and crops. We estimate the mass of emitted bacteria- to be 40–1800 Gg a−1, depending on the mass fraction of bacterial cells in the particles. In order to improve understanding of this topic, more measurements of the bacterial content of the air and of the rate of surface-atmosphere exchange of bacteria will be necessary. Future observations in wetlands, hot deserts, tundra, remote glacial and coastal regions and over oceans will be of particular interest.

Viability and respiratory activity ofPseudomonas syringaecells starved in buffer

1995 ◽  
Vol 41 (4-5) ◽  
pp. 372-377 ◽  
Author(s):  
João P. S. Cabral
Keyword(s):  
Oxygen Consumption ◽  
Electron Transport ◽  
Pseudomonas Syringae ◽  
Respiratory Activity ◽  
Bacterial Cells ◽  
Intact Cells ◽  
Rate Of Oxygen Consumption ◽  
Metabolic Activities ◽  
Different Levels ◽  
Number Of Cells

Pseudomonas syringae cells starved in buffer released orcinol-reactive molecules and materials that absorbed ultraviolet light. The number of cells culturable in nutrient medium decreased more rapidly than the number of intact particles determined by microscopy. The results suggested that starvation resulted in the lysis of an increasing number of cells, and that a fraction of the intact particles were not culturable. Starvation also resulted in a decrease in the rate of oxygen consumption with acetate, glycerol, and succinate, but at different levels. Whereas the respiration of acetate and glycerol decreased concomitantly with culturability, the respiration of succinate decreased to levels similar to the concentration of intact cells, suggesting that all intact particles respired the succinate, but only the culturable cells respired the acetate and glycerol. The results suggest that measuring the activity of the electron-transport system can overestimate the viability of starved bacterial cells, and that complex metabolic activities such as the respiration of acetate and glycerol are probably better suited for the evaluation of this parameter.Key words: Pseudomonas syringae, starvation, culturability, viability, respiration.

scholarly journals Microbial Photoinactivation by Visible Light Results in Limited Loss of Membrane Integrity

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 341
Author(s):  
Katharina Hoenes ◽  
Richard Bauer ◽  
Barbara Spellerberg ◽  
Martin Hessling
Keyword(s):  
Visible Light ◽  
Pseudomonas Fluorescens ◽  
Bacterial Cell ◽  
Bacterial Species ◽  
Membrane Integrity ◽  
Cell Lysis ◽  
Microbial Inactivation ◽  
Bacterial Cells ◽  
Resistance Development ◽  
Transmission Electron

Interest in visible light irradiation as a microbial inactivation method has widely increased due to multiple possible applications. Resistance development is considered unlikely, because of the multi-target mechanism, based on the induction of reactive oxygen species by wavelength specific photosensitizers. However, the affected targets are still not completely identified. We investigated membrane integrity with the fluorescence staining kit LIVE/DEAD® BacLight™ on a Gram positive and a Gram negative bacterial species, irradiating Staphylococcus carnosus and Pseudomonas fluorescens with 405 nm and 450 nm. To exclude the generation of viable but nonculturable (VBNC) bacterial cells, we applied an ATP test, measuring the loss of vitality. Pronounced uptake of propidium iodide was only observed in Pseudomonas fluorescens at 405 nm. Transmission electron micrographs revealed no obvious differences between irradiated samples and controls, especially no indication of an increased bacterial cell lysis could be observed. Based on our results and previous literature, we suggest that visible light photoinactivation does not lead to rapid bacterial cell lysis or disruption. However, functional loss of membrane integrity due to depolarization or inactivation of membrane proteins may occur. Decomposition of the bacterial envelope following cell death might be responsible for observations of intracellular component leakage.

Comparative analysis of the transferrin and lactoferrin binding proteins in the family Neisseriaceae

1989 ◽  
Vol 35 (3) ◽  
pp. 409-415 ◽  
Author(s):  
Anthony B. Schryvers ◽  
B. Craig Lee
Keyword(s):  
Binding Proteins ◽  
Solid Phase ◽  
Bacterial Species ◽  
Binding Activity ◽  
Intact Cells ◽  
Human Transferrin ◽  
Affinity Isolation ◽  
Lactoferrin Receptor ◽  
Solid Phase Binding ◽  
Branhamella Catarrhalis

Intact cells of several bacterial species were tested for their ability to bind human transferrin and lactoferrin by a solid-phase binding assay using horseradish peroxidase conjugated transferrin and lactoferrin. The ability to bind lactoferrin was detected in all isolates of Neisseria and Branhamella catarrhalis but not in isolates of Escherichia coli or Pseudomonas aeruginosa. Transferrin-binding activity was similarly detected in most isolates of Neisseria and Branhamella but not in E. coli or P. aeruginosa. The expression of transferrin- and lactoferrin-binding activity was induced by addition of ethylenediamine di-o-phenylacetic acid and reversed by excess FeCl3, indicating regulation by the level of available iron in the medium. The transferrin receptor was specific for human transferrin and the lactoferrin receptor had a high degree of specificity for human lactoferrin in all species tested. The transferrin- and lactoferrin-binding proteins were identified after affinity isolation using biotinylated human transferrin or lactoferrin and streptavidin–agarose. The lactoferrin-binding protein was identified as a 105-kilodalton protein in all species tested. Affinity isolation with biotinylated transferrin yielded two or more proteins in all species tested. A high molecular mass protein was observed in all isolates, and was of similar size (approximately 98 kilodaltons) in all species of Neisseria but was larger (105 kilodaltons) in B. catarrhalis.Key words: iron, Neisseria, transferrin, lactoferrin, receptor.

Antimicrobial Activity of Gaseous Allyl Isothiocyanate

1997 ◽  
Vol 60 (8) ◽  
pp. 943-947 ◽  
Author(s):  
PASCAL J. DELAQUIS ◽  
PETER L. SHOLBERG
Keyword(s):  
Bacterial Species ◽  
Allyl Isothiocyanate ◽  
Model System ◽  
Penicillium Expansum ◽  
Escherichia Coli O157 ◽  
Fluorescent Pseudomonad ◽  
Bacterial Cells ◽  
E Coli ◽  
Simple Model System ◽  
Germination And Growth

A simple model system was constructed to evaluate the microbistatic and microbicidal properties of gaseous allyl isothiocyanate (AIT) against bacterial cells and fungal conidia deposited on agar surfaces. Salmonella typhimurium, Listeria monocytogenes Scott A, and Escherichia coli O157:H7 were inhibited when exposed to 1,000 μg AIT per liter. Pseudomonas corrugata, a Cytophaga species, and a fluorescent pseudomonad failed to grow in the presence of 500 μg AIT per liter. Germination and growth of Penicillium expansum, Aspergillus flavus, and Botrytis cinerea conidia was inhibited in the presence of 100 μg AIT per liter. Bactericidal and sporicidal activities varied with strain and increased with time of exposure, AIT concentration, and temperature. E. coli O157:H7 was the most resistant bacterial species tested.

scholarly journals Molecular architecture of theLegionellaDot/Icm type IV secretion system

2018 ◽  
Author(s):  
Debnath Ghosal ◽  
Yi-Wei Chang ◽  
Kwang Cheol Jeong ◽  
Joseph P. Vogel ◽  
Grant J. Jensen
Keyword(s):  
Legionella Pneumophila ◽  
Cell Envelope ◽  
Secretion System ◽  
Host Cells ◽  
Molecular Architecture ◽  
Intact Cells ◽  
Type Iv ◽  
Type Ivb Secretion ◽  
Electron Cryotomography ◽  
First Time

AbstractLegionella pneumophilasurvives and replicates inside host cells by secreting ~300 effectors through the Dot/Icm type IVB secretion system (T4BSS). Understanding this machine’s structure is challenging because of its large number of components (27) and integration into all layers of the cell envelope. Previously we overcame this obstacle by imaging the Dot/Icm T4BSS in its native state within intact cells through electron cryotomography. Here we extend our observations by imaging a stabilized mutant that yielded a higher resolution map. We describe for the first time the presence of a well-ordered central channel that opens up into a windowed large (~32 nm wide) secretion chamber with an unusual 13-fold symmetry. We then dissect the complex by matching proteins to densities for many components, including all those with periplasmic domains. The placement of known and predicted structures of individual proteins into the map reveals the architecture of the T4BSS and provides a roadmap for further investigation of this amazing specialized secretion system.

scholarly journals Polyvalent Bacterial Lysate Protects Against Pneumonia Independently of Neutrophils, IL-17A or Caspase-1 Activation

2021 ◽  
Vol 12 ◽  
Author(s):  
Florencia Ferrara ◽  
Analía Rial ◽  
Norma Suárez ◽  
José Alejandro Chabalgoity
Keyword(s):  
Biological Activity ◽  
Protective Effect ◽  
Pneumococcal Pneumonia ◽  
Respiratory Infections ◽  
Bacterial Species ◽  
Dependent Manner ◽  
Bacterial Cells ◽  
Active Components ◽  
Caspase 1 ◽  
Bacterial Lysates

Polyvalent bacterial lysates have been in use for decades for prevention and treatment of respiratory infections with reported clinical benefits. However, besides claims of broad immune activation, the mode of action is still a matter of debate. The lysates, formulated with the main bacterial species involved in respiratory infections, are commonly prepared by chemical or mechanical disruption of bacterial cells, what is believed influences the biological activity of the product. Here, we prepared two polyvalent lysates with the same composition but different method of bacterial cell disruption and evaluated their biological activity in a comparative fashion. We found that both bacterial lysates induce NF-kB activation in a MyD88 dependent manner, suggesting they work as TLR agonists. Further, we found that a single intranasal dose of any of the two lysates, is sufficient to protect against pneumococcal pneumonia, suggesting that they exert similar biological activity. We have previously shown that protection against pneumococcal pneumonia can also be induced by prior S. pneumoniae sub lethal infection or therapeutic treatment with a TLR5 agonist. Protection in those cases depends on neutrophil recruitment to the lungs, and can be associated with increased local expression of IL-17A. Here, we show that bacterial lysates exert protection against pneumococcal pneumonia independently of neutrophils, IL-17A or Caspase-1/11 activation, suggesting the existence of redundant mechanisms of protection. Trypsin-treated lysates afford protection to the same extent, suggesting that just small peptides suffice to exert the protective effect or that the molecules responsible for the protective effect are not proteins. Understanding the mechanism of action of bacterial lysates and deciphering the active components shall allow redesigning them with more precisely defined formulations and expanding their range of action.

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.

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