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.

Effectiveness and Functional Mechanism of a Multicomponent Sanitizer against Biofilms Formed by Escherichia coli O157:H7 and Five Salmonella Serotypes Prevalent in the Meat Industry

2020 ◽  
Vol 83 (4) ◽  
pp. 568-575
Author(s):  
RONG WANG ◽  
YOU ZHOU ◽  
NORASAK KALCHAYANAND ◽  
DAYNA M. HARHAY ◽  
TOMMY L. WHEELER
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Three Dimensional ◽  
Short Exposure ◽  
Escherichia Coli O157 ◽  
Bacterial Cells ◽  
Meat Processing ◽  
E Coli ◽  
Biofilm Removal ◽  
Biofilm Structure

ABSTRACT Biofilm formation by Escherichia coli O157:H7 and Salmonella enterica at meat processing plants poses a potential risk of meat product contamination. Many common sanitizers are unable to completely eradicate biofilms formed by these foodborne pathogens because of the three-dimensional biofilm structure and the presence of bacterial extracellular polymeric substances (EPSs). A novel multifaceted approach combining multiple chemical reagents with various functional mechanisms was used to enhance the effectiveness of biofilm control. We tested a multicomponent sanitizer consisting of a quaternary ammonium compound (QAC), hydrogen peroxide, and the accelerator diacetin for its effectiveness in inactivating and removing Escherichia coli O157:H7 and Salmonella enterica biofilms under meat processing conditions. E. coli O157:H7 and Salmonella biofilms on common contact surfaces were treated with 10, 20, or 100% concentrations of the multicomponent sanitizer solution for 10 min, 1 h, or 6 h, and log reductions in biofilm mass were measured. Scanning electron microscopy (SEM) was used to directly observe the effect of sanitizer treatment on biofilm removal and bacterial morphology. After treatment with the multicomponent sanitizer, viable E. coli O157:H7 and Salmonella biofilm cells were below the limit of detection, and the prevalence of both pathogens was low. After treatment with a QAC-based control sanitizer, surviving bacterial cells were countable, and pathogen prevalence was higher. SEM analysis of water-treated control samples revealed the three-dimensional biofilm structure with a strong EPS matrix connecting bacteria and the contact surface. Treatment with 20% multicomponent sanitizer for 10 min significantly reduced biofilm mass and weakened the EPS connection. The majority of the bacterial cells had altered morphology and compromised membrane integrity. Treatment with 100% multicomponent sanitizer for 10 min dissolved the EPS matrix, and no intact biofilm structure was observed; instead, scattered clusters of bacterial aggregates were detected, indicating the loss of cell viability and biofilm removal. These results indicate that the multicomponent sanitizer is effective, even after short exposure with dilute concentrations, against E. coli O157:H7 and S. enterica biofilms. HIGHLIGHTS

scholarly journals High Rates of Conjugation in Bacterial Biofilms as Determined by Quantitative In Situ Analysis

1999 ◽  
Vol 65 (8) ◽  
pp. 3710-3713 ◽  
Author(s):  
Martina Hausner ◽  
Stefan Wuertz
Keyword(s):  
Laser Scanning ◽  
Nutrient Concentration ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Biofilms ◽  
Conjugative Gene Transfer ◽  
Biofilm Structure

ABSTRACT Quantitative in situ determination of conjugative gene transfer in defined bacterial biofilms using automated confocal laser scanning microscopy followed by three-dimensional analysis of cellular biovolumes revealed conjugation rates 1,000-fold higher than those determined by classical plating techniques. Conjugation events were not affected by nutrient concentration alone but were influenced by time and biofilm structure.

The effect of gold and silver nanoparticles, chitosan and their combinations on bacterial biofilms of food-borne pathogens

Biofouling ◽  
2020 ◽  
Vol 36 (2) ◽  
pp. 222-233 ◽  
Author(s):  
Ondrej Chlumsky ◽  
Sabina Purkrtova ◽  
Hana Michova (Turonova) ◽  
Viviana Svarcova (Fuchsova) ◽  
Petr Slepicka ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Bacterial Biofilms ◽  
Gold And Silver Nanoparticles ◽  
Food Borne Pathogens ◽  
Food Borne

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 Fast Overlap Detection between Hard-Core Colloidal Cuboids and Spheres. The OCSI Algorithm

Algorithms ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 72
Author(s):  
Luca Tonti ◽  
Alessandro Patti
Keyword(s):  
Colloidal Particles ◽  
Dynamic Properties ◽  
Wide Spectrum ◽  
Three Dimensional ◽  
Hard Core ◽  
Detection Algorithm ◽  
Three Dimensional Objects ◽  
Aggregation Behaviour ◽  
Sphere Radius ◽  
User Friendly

Collision between rigid three-dimensional objects is a very common modelling problem in a wide spectrum of scientific disciplines, including Computer Science and Physics. It spans from realistic animation of polyhedral shapes for computer vision to the description of thermodynamic and dynamic properties in simple and complex fluids. For instance, colloidal particles of especially exotic shapes are commonly modelled as hard-core objects, whose collision test is key to correctly determine their phase and aggregation behaviour. In this work, we propose the Oriented Cuboid Sphere Intersection (OCSI) algorithm to detect collisions between prolate or oblate cuboids and spheres. We investigate OCSI’s performance by bench-marking it against a number of algorithms commonly employed in computer graphics and colloidal science: Quick Rejection First (QRI), Quick Rejection Intertwined (QRF) and a vectorized version of the OBB-sphere collision detection algorithm that explicitly uses SIMD Streaming Extension (SSE) intrinsics, here referred to as SSE-intr. We observed that QRI and QRF significantly depend on the specific cuboid anisotropy and sphere radius, while SSE-intr and OCSI maintain their speed independently of the objects’ geometry. While OCSI and SSE-intr, both based on SIMD parallelization, show excellent and very similar performance, the former provides a more accessible coding and user-friendly implementation as it exploits OpenMP directives for automatic vectorization.

scholarly journals Exploring electroactive microenvironments in polymer-based nanocomposites to sensitize bacterial cells to low-dose embedded silver nanoparticles

2021 ◽  
Author(s):  
Joana Moreira ◽  
Margarida M. Fernandes ◽  
Estela O. Carvalho ◽  
Ana Nicolau ◽  
Vesna Lazic ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Low Dose ◽  
Bacterial Cells

Synthesis of N ‐Acetylcysteine Conjugated Cholic Acid Stabilized Gold and Silver Nanoparticles: Evaluation of Their Catalytic Activity and Toxicity Assessment

2021 ◽  
Vol 6 (22) ◽  
pp. 5474-5487
Author(s):  
Nishanthi Ezhumalai ◽  
Manivannan Nanthagopal ◽  
Shanmugam Chandirasekar ◽  
Manikandan Elumalai ◽  
Mathivanan Narayanasamy ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Activity ◽  
Cholic Acid ◽  
Toxicity Assessment ◽  
Gold And Silver Nanoparticles

scholarly journals Isolation and Optimization of Culture Conditions of Thraustochytrium kinnei for Biomass Production, Nanoparticle Synthesis, Antioxidant and Antimicrobial Activities

2021 ◽  
Vol 9 (6) ◽  
pp. 678
Author(s):  
Kaliyamoorthy Kalidasan ◽  
Nabikhan Asmathunisha ◽  
Venugopal Gomathi ◽  
Laurent Dufossé ◽  
Kandasamy Kathiresan
Keyword(s):  
Antimicrobial Activity ◽  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Biomass Production ◽  
Petroleum Ether Extract ◽  
Antimicrobial Activities ◽  
Culture Conditions ◽  
Gold And Silver Nanoparticles ◽  
Optimization Of Culture Conditions ◽  
Antioxidant And Antimicrobial Activities

This work deals with the identification of a predominant thraustochytrid strain, the optimization of culture conditions, the synthesis of nanoparticles, and the evaluation of antioxidant and antimicrobial activities in biomass extracts and nanoparticles. Thraustochytrium kinnei was identified as a predominant strain from decomposing mangrove leaves, and its culture conditions were optimized for maximum biomass production of 13.53 g·L−1, with total lipids of 41.33% and DHA of 39.16% of total fatty acids. Furthermore, the strain was shown to synthesize gold and silver nanoparticles in the size ranges of 10–85 nm and 5–90 nm, respectively. Silver nanoparticles exhibited higher total antioxidant and DPPH activities than gold nanoparticles and methanol extract of the strain. The silver nanoparticles showed higher antimicrobial activity than gold nanoparticles and petroleum ether extract of the strain. Thus, Thraustochytrium kinnei is proven to be promising for synthesis of silver nanoparticles with high antioxidant and antimicrobial activity.

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