scholarly journals Mechanics of biofilms formed of bacteria with fimbriae appendages

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243280
Author(s):  
Xing Jin ◽  
Jeffrey S. Marshall
Keyword(s):  
Drag Force ◽  
Bacterial Cell ◽  
Bacterial Biofilms ◽  
Bacterial Cells ◽  
Cell Alignment ◽  
Bacterial Colony ◽  
Viscous Shear ◽  
Tensile Forces ◽  
Biofilm Structure ◽  
Viscous Torque

Gram-negative bacteria, as well as some Gram-positive bacteria, possess hair-like appendages known as fimbriae, which play an important role in adhesion of the bacteria to surfaces or to other bacteria. Unlike the sex pili or flagellum, the fimbriae are quite numerous, with of order 1000 fimbriae appendages per bacterial cell. In this paper, a recently developed hybrid model for bacterial biofilms is used to examine the role of fimbriae tension force on the mechanics of bacterial biofilms. Each bacterial cell is represented in this model by a spherocylindrical particle, which interact with each other through collision, adhesion, lubrication force, and fimbrial force. The bacterial cells absorb water and nutrients and produce extracellular polymeric substance (EPS). The flow of water and EPS, and nutrient diffusion within these substances, is computed using a continuum model that accounts for important effects such as osmotic pressure gradient, drag force on the bacterial cells, and viscous shear. The fimbrial force is modeled using an outer spherocylinder capsule around each cell, which can transmit tensile forces to neighboring cells with which the fimbriae capsule collides. We find that the biofilm structure during the growth process is dominated by a balance between outward drag force on the cells due to the EPS flow away from the bacterial colony and the inward tensile fimbrial force acting on chains of cells connected by adhesive fimbriae appendages. The fimbrial force also introduces a large rotational motion of the cells and disrupts cell alignment caused by viscous torque imposed by the EPS flow. The current paper characterizes the competing effects of EPS drag and fimbrial force using a series of computations with different values of the ratio of EPS to bacterial cell production rate and different numbers of fimbriae per cell.

scholarly journals Interactions of Gold and Silver Nanoparticles with Bacterial Biofilms: Molecular Interactions behind Inhibition and Resistance

2020 ◽  
Vol 21 (20) ◽  
pp. 7658
Author(s):  
Abhayraj S. Joshi ◽  
Priyanka Singh ◽  
Ivan Mijakovic
Keyword(s):  
Silver Nanoparticles ◽  
Molecular Interactions ◽  
Wide Spectrum ◽  
Three Dimensional ◽  
Antimicrobial Effect ◽  
Bacterial Biofilms ◽  
Bacterial Cells ◽  
Gold And Silver Nanoparticles ◽  
Almost All ◽  
Biofilm Structure

Many bacteria have the capability to form a three-dimensional, strongly adherent network called ‘biofilm’. Biofilms provide adherence, resourcing nutrients and offer protection to bacterial cells. They are involved in pathogenesis, disease progression and resistance to almost all classical antibiotics. The need for new antimicrobial therapies has led to exploring applications of gold and silver nanoparticles against bacterial biofilms. These nanoparticles and their respective ions exert antimicrobial action by damaging the biofilm structure, biofilm components and hampering bacterial metabolism via various mechanisms. While exerting the antimicrobial activity, these nanoparticles approach the biofilm, penetrate it, migrate internally and interact with key components of biofilm such as polysaccharides, proteins, nucleic acids and lipids via electrostatic, hydrophobic, hydrogen-bonding, Van der Waals and ionic interactions. Few bacterial biofilms also show resistance to these nanoparticles through similar interactions. The nature of these interactions and overall antimicrobial effect depend on the physicochemical properties of biofilm and nanoparticles. Hence, study of these interactions and participating molecular players is of prime importance, with which one can modulate properties of nanoparticles to get maximal antibacterial effects against a wide spectrum of bacterial pathogens. This article provides a comprehensive review of research specifically directed to understand the molecular interactions of gold and silver nanoparticles with various bacterial biofilms.

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.

How Physical Interactions Shape Bacterial Biofilms

2021 ◽  
Vol 50 (1) ◽  
Author(s):  
Berenike Maier
Keyword(s):  
Extracellular Matrix ◽  
Environmental Changes ◽  
Bacterial Biofilms ◽  
Annual Review ◽  
Publication Date ◽  
Extracellular Matrix Components ◽  
Macroscopic Objects ◽  
Physical Interactions ◽  
Repulsive Forces ◽  
Biofilm Structure

Biofilms are structured communities formed by a single or multiple microbial species. Within biofilms, bacteria are embedded into extracellular matrix, allowing them to build macroscopic objects. Biofilm structure can respond to environmental changes such as the presence of antibiotics or predators. By adjusting expression levels of surface and extracellular matrix components, bacteria tune cell-to-cell interactions. One major challenge in the field is the fact that these components are very diverse among different species. Deciphering how physical interactions within biofilms are affected by changes in gene expression is a promising approach to obtaining a more unified picture of how bacteria modulate biofilms. This review focuses on recent advances in characterizing attractive and repulsive forces between bacteria in correlation with biofilm structure, dynamics, and spreading. How bacteria control physical interactions to maximize their fitness is an emerging theme. Expected final online publication date for the Annual Review of Biophysics, Volume 50 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Bacterial Cell Inactivation Using a Single-Frequency Batch-Type Ultrasound Device

2021 ◽  
Vol 6 (1) ◽  
pp. 65-80
Author(s):  
Poetro Sambegoro ◽  
Maya Fitriyanti ◽  
Bentang Arief Budiman ◽  
Kamarisima Kamarisima ◽  
Sekar Wangi Arraudah Baliwangi ◽  
...  
Keyword(s):  
Bacterial Cell ◽  
Treatment Time ◽  
Low Cost ◽  
Single Frequency ◽  
Bacterial Cells ◽  
Cell Inactivation ◽  
E Coli ◽  
Commercial System ◽  
Ultrasound Device ◽  
Frequency Ultrasound

Ultrasound technology employs cavitation to generate high-pressure soundwaves to disrupt bacterial cells. This study reveals the effectiveness of a single frequency ultrasound device for bacterial cell inactivation. A low-cost ultrasound device having a single frequency, i.e. 22 kHz for lab-scale application, was developed first, and the prototype was mechanically designed and analyzed using the finite-element method to assure the targeted natural frequency could be achieved. The prototype was then tested inactivating bacterial cells, Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), in a simple medium and a food system, and the results were then compared to a commercial system. A treatment time of up to 15 minutes was able to reduce E. coli and B. subtilis cells by 3.3 log and 2.8 log, respectively, and these results were similar to those of the commercial system. The effectiveness of bacterial cell inactivation using the developed single-frequency ultrasound device is then discussed. The findings are useful for designing low-cost ultrasound devices for application in the food industry.

scholarly journals Antimicrobial Resistance in Oral biofilm: Challenges and Alternatives

2021 ◽  
Vol 12 (1) ◽  
pp. 349-356
Author(s):  
Satish Kumar Sharma ◽  
Shmmon Ahmad
Keyword(s):  
Antimicrobial Resistance ◽  
Bacterial Infections ◽  
Molecular Mechanisms ◽  
Resistance Mechanisms ◽  
Bacterial Biofilm ◽  
Bacterial Biofilms ◽  
Target Cells ◽  
Bacterial Cells ◽  
Antimicrobial Drugs ◽  
Oral Infections

Bacterial biofilm has been a major contributor to severe bacterial infections in humans. Oral infections have also been associated with biofilm-forming microbes. Several antimicrobial strategies have been developed to combat bacterial biofilms. However, the complexity of the oral cavity has made it difficult to use common drug treatments. Most effective ways to control normal bacterial infections are rendered ineffective for bacterial biofilms. Due to limited drug concentration availability, drug neutralization or altered phenotype of bacterial cells, different drug have been ineffective to identify the target cells. This leads to the development of the multifaceted phenomenon of antimicrobial resistance (AMR). Biofilm research done so far has been focused on using antimicrobial drugs to target molecular mechanisms of cells. The severity and resistance mechanisms of extracellular matrix (ECM) have been underestimated. The present study describes different antimicrobial strategies with respect to their applications in dental or oral infections. A prospective strategy has been proposed targeting ECM which is expected to provide an insight on biofilm obstinacy and antimicrobial resistance.

scholarly journals Effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential / Vpliv naravnih protimikrobnih snovi na bakterijsko hidrofobnost, adhezijo in zeta potencial

2016 ◽  
Vol 67 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Marija Kurinčič ◽  
Barbara Jeršek ◽  
Anja Klančnik ◽  
Sonja Smole Možina ◽  
Rok Fink ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Bacterial Adhesion ◽  
Bacterial Cell ◽  
Early Stage ◽  
Experimental Studies ◽  
Adhesion Prevention ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Natural Antimicrobials ◽  
Cell Hydrophobicity

Abstract Interactions between bacterial cells and contact materials play an important role in food safety and technology. As bacterial strains become ever more resistant to antibiotics, the aim of this study was to analyse adhesion of selected foodborne bacterial strains on polystyrene surface and to evaluate the effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential as strategies of adhesion prevention. The results showed strain-specific adhesion rate on polystyrene. The lowest and the highest adhesion were found for two B. cereus lines. Natural antimicrobials ferulic and rosmarinic acid substantially decreased adhesion, whereas the effect of epigallocatechin gallate was neglectful. Similar results were found for the zeta potential, indicating that natural antimicrobials reduce bacterial adhesion. Targeting bacterial adhesion using natural extracts we can eliminate potential infection at an early stage. Future experimental studies should focus on situations that are as close to industrial conditions as possible.

Magnesium and calcium ions: roles in bacterial cell attachment and biofilm structure maturation

Biofouling ◽  
2019 ◽  
Vol 35 (9) ◽  
pp. 959-974 ◽  
Author(s):  
Tianyang Wang ◽  
Steve Flint ◽  
Jon Palmer
Keyword(s):  
Calcium Ions ◽  
Bacterial Cell ◽  
Cell Attachment ◽  
Biofilm Structure

scholarly journals Factors That Affect the Enlargement of Bacterial Protoplasts and Spheroplasts

2020 ◽  
Vol 21 (19) ◽  
pp. 7131
Author(s):  
Hiromi Nishida
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Bacterial Cell ◽  
Metal Ion ◽  
Bacterial Species ◽  
Bacterial Cells ◽  
Cell Enlargement ◽  
Ion Composition ◽  
Gene Manipulation ◽  
Peptidoglycan Biosynthesis

Cell enlargement is essential for the microinjection of various substances into bacterial cells. The cell wall (peptidoglycan) inhibits cell enlargement. Thus, bacterial protoplasts/spheroplasts are used for enlargement because they lack cell wall. Though bacterial species that are capable of gene manipulation are limited, procedure for bacterial cell enlargement does not involve any gene manipulation technique. In order to prevent cell wall resynthesis during enlargement of protoplasts/spheroplasts, incubation media are supplemented with inhibitors of peptidoglycan biosynthesis such as penicillin. Moreover, metal ion composition in the incubation medium affects the properties of the plasma membrane. Therefore, in order to generate enlarged cells that are suitable for microinjection, metal ion composition in the medium should be considered. Experiment of bacterial protoplast or spheroplast enlargement is useful for studies on bacterial plasma membrane biosynthesis. In this paper, we have summarized the factors that influence bacterial cell enlargement.

scholarly journals Nitroxide Functionalized Antibiotics Are Promising Eradication Agents against Staphylococcus aureus Biofilms

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Anthony D. Verderosa ◽  
Rabeb Dhouib ◽  
Kathryn E. Fairfull-Smith ◽  
Makrina Totsika
Keyword(s):  
Staphylococcus Aureus ◽  
Bacterial Biofilms ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Microscopy Analysis ◽  
Biofilm Dispersal ◽  
Biofilm Structure ◽  
Dispersal Activity

ABSTRACT Treatment of biofilm-related Staphylococcus aureus infections represents an important medical challenge worldwide, as biofilms, even those involving drug-susceptible S. aureus strains, are highly refractory to conventional antibiotic therapy. Nitroxides were recently shown to induce the dispersal of Gram-negative biofilms in vitro, but their action against Gram-positive bacterial biofilms remains unknown. Here, we demonstrate that the biofilm dispersal activity of nitroxides extends to S. aureus, a clinically important Gram-positive pathogen. Coadministration of the nitroxide CTEMPO (4-carboxy-2,2,6,6-tetramethylpiperidin-1-yloxyl) with ciprofloxacin significantly improved the biofilm eradication activity of the antibiotic against S. aureus. Moreover, covalently linking the nitroxide to the antibiotic moiety further reduced the ciprofloxacin minimal biofilm eradication concentration. Microscopy analysis revealed that fluorescent nitroxide-antibiotic hybrids could penetrate S. aureus biofilms and enter cells localized at the surface and base of the biofilm structure. No toxicity to human cells was observed for the nitroxide CTEMPO or the nitroxide-antibiotic hybrids. Taken together, our results show that nitroxides can mediate the dispersal of Gram-positive biofilms and that dual-acting biofilm eradication antibiotics may provide broad-spectrum therapies for the treatment of biofilm-related infections.

Analysis of the Crushing Effect about Ultrasound on E. coli and B. subtilis

2012 ◽  
Vol 260-261 ◽  
pp. 1017-1021
Author(s):  
Xin Ying Wang ◽  
Yong Tao Liu ◽  
Min Hui ◽  
Ji Fei Xu
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Bacillus Subtilis ◽  
Bacterial Cell ◽  
Logarithmic Phase ◽  
Growth Stages ◽  
Bacterial Cells ◽  
E Coli ◽  
Different Growth Stages ◽  
Main Factor

Escherichia coli and Bacillus subtilis as objects of the study, ultrasonic fragmentation acted on the bacterial cells in different growth stages, results showed that, it’s similar to the crushing effect of ultrasound on E. coli and B. subtilis cells of different growth stages, the highest crushing rate in the logarithmic phase, reached to 95.8% and 94.3% respectively, the crushing rate of adjustment phase is lowest, maintained at around 60%, the crushing rate stability cell was centered, which can be achieved 90%. The structure of the bacterial cell wall didn’t the main factor to decide the ultrasonic fragmentation effect, but different growth periods of bacterial cells did the determinant.

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