scholarly journals Massive Integration of Planktonic Cells within a Developing Biofilm

2021 ◽  
Vol 9 (2) ◽  
pp. 298
Author(s):  
Nay El-Khoury ◽  
Imene Bennaceur ◽  
Emilie Verplaetse ◽  
Stéphane Aymerich ◽  
Didier Lereclus ◽  
...  
Keyword(s):  
Glass Tube ◽  
Time Lapse ◽  
Measurement Methods ◽  
Planktonic Cells ◽  
Spectrophotometric Measurement ◽  
Biofilm Growth ◽  
Continuous Growth ◽  
A Value ◽  
Two Populations ◽  
Sessile Cells

During biofilm growth, the coexistence of planktonic and sessile cells can lead to dynamic exchanges between the two populations. We have monitored the fate of these populations in glass tube assays, where the Bacillus thuringiensis 407 strain produces a floating pellicle. Time-lapse spectrophotometric measurement methods revealed that the planktonic population grew until the pellicle started to be produced. Thereafter, the planktonic population decreased rapidly down to a value close to zero while the biofilm was in continuous growth, showing no dispersal until 120 h of culture. We found that this decrease was induced by the presence of the pellicle, but did not occur when oxygen availability was limited, suggesting that it was independent of cell death or cell sedimentation and that the entire planktonic population has integrated the biofilm. To follow the distribution of recruited planktonic cells within the pellicle, we tagged planktonic cells with GFP and sessile cells with mCherry. Fluorescence binocular microscopy observations revealed that planktonic cells, injected through a 24-h-aged pellicle, were found only in specific areas of the biofilm, where the density of sessile cells was low, showing that spatial heterogeneity can occur between recruited cells and sessile cells in a monospecies biofilm.

Biofilm Formation and Biocides Sensitivity of Pseudomonas marginalis Isolated from a Maple Sap Collection System

2006 ◽  
Vol 69 (10) ◽  
pp. 2411-2416 ◽  
Author(s):  
L. LAGACÉ ◽  
M. JACQUES ◽  
A. A. MAFU ◽  
D. ROY
Keyword(s):  
Sodium Hypochlorite ◽  
Peracetic Acid ◽  
Biofilm Formation ◽  
Planktonic Cells ◽  
Collection System ◽  
Biofilm Growth ◽  
Biofilm Production ◽  
Different Temperatures ◽  
Maple Sap ◽  
Scanning Electron

The susceptibility of planktonic and biofilm cells of Pseudomonas marginalis toward four commonly used biocides at different temperatures (15 and 30°C) and biofilm growth times (24 and 48 h) was assessed. Using the MBEC biofilm device, biofilm production in maple sap was shown to be highly reproducible for each set of conditions tested. Biofilm formation was influenced by growth temperature and time. A temperature of 15°C and incubation time of 24 h yielded fewer CFU per peg and showed fewer adhered cells and typical biofilm structures, based on scanning electron microscopy observations as compared with other conditions. Minimal biofilm eradication concentration values for P. marginalis were significantly greater (P < 0.001) than were MBCs for planktonic cells and for every biocide tested, with the exception of minimal biofilm eradication concentration values for peracetic acid at 15°C and 24 h. Sodium hypochlorite and peracetic acid sanitizers were able to eliminate P. marginalis biofilms at lower concentrations as compared with hydrogen peroxide– and quaternary ammonium– based sanitizers (P < 0.001). According to the results obtained, sodium hypochlorite and peracetic acid sanitizers would be more appropriate for maple sap collection system sanitation.

scholarly journals Effect of Eugenol on Cell Surface Hydrophobicity, Adhesion, and Biofilm ofCandida tropicalisandCandida dubliniensisIsolated from Oral Cavity of HIV-Infected Patients

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Suelen Balero de Paula ◽  
Thais Fernanda Bartelli ◽  
Vanessa Di Raimo ◽  
Jussevania Pereira Santos ◽  
Alexandre Tadachi Morey ◽  
...  
Keyword(s):  
Cell Surface ◽  
Oral Cavity ◽  
Biofilm Formation ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Planktonic Cells ◽  
Hydrophobic Behavior ◽  
Significant Difference ◽  
Substrate Surfaces ◽  
Sessile Cells

MostCandidaspp. infections are associated with biofilm formation on host surfaces. Cells within these communities display a phenotype resistant to antimicrobials and host defenses, so biofilm-associated infections are difficult to treat, representing a source of reinfections. The present study evaluated the effect of eugenol on the adherence properties and biofilm formation capacity ofCandida dubliniensisandCandida tropicalisisolated from the oral cavity of HIV-infected patients. All isolates were able to form biofilms on different substrate surfaces. Eugenol showed inhibitory activity against planktonic and sessile cells ofCandidaspp. No metabolic activity in biofilm was detected after 24 h of treatment. Scanning electron microscopy demonstrated that eugenol drastically reduced the number of sessile cells on denture material surfaces. MostCandidaspecies showed hydrophobic behavior and a significant difference in cell surface hydrophobicity was observed after exposure of planktonic cells to eugenol for 1 h. Eugenol also caused a significant reduction in adhesion of mostCandidaspp. to HEp-2 cells and to polystyrene. These findings corroborate the effectiveness of eugenol againstCandidaspecies other thanC. albicans, reinforcing its potential as an antifungal applied to limit both the growth of planktonic cells and biofilm formation on different surfaces.

scholarly journals EXAMINATION OF WORKER‐LOCATION MEASUREMENT METHODS AS A RESEARCH TOOL FOR AUTOMATED LABOR CONTROL

2010 ◽  
Vol 16 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Ronie Navon ◽  
Eytan Goldschmidt
Keyword(s):  
Performance Measurement ◽  
Reliable Method ◽  
Time Lapse ◽  
Measurement Methods ◽  
Labor Control ◽  
The Third ◽  
Labor Inputs ◽  
Adequate Research ◽  
Location Measurement ◽  
Research Tools

Automatic labor performance measurement is a challenging area of research. Little work has been done in this area due to its complexity and the absence of adequate research tools. The authors used the approach of indirect parameters to automate the performance measurement. In this approach, the location of the worker is measured as a function of time and special algorithms convert these data into labor inputs, or productivity. Research in this area requires a reliable method, or tool, for workers location measurement ‐ such a tool does not exist. Three methods of location measurement are examined in this paper as research tools for automated labor control: (1) manual simulation of location measurement, (2) GPS, and (3) video photography. The first two methods were found to be subjective, inaccurate and unreliable. The third was found to be suitable for the purpose of the present research. This method uses a classical time‐lapse technique, together with a video‐based method developed in the present research. Santrauka Automatizuotas darbu atlikimo ivertinimas yra aktuali tyrimu sritis. Šioje srityje nera atlikta daug tyrimu del jos sudetingumo ir tinkamu tyrimo priemoniu stokos. Ivertinimui automatizuoti autoriai taike netiesioginiu rodikliu būda. Šiame tyrime darbininko buvimo vieta matuojama kaip laiko funkcija ir naudojant specialius algoritmus šie duomenys konvertuojami i darbo ivesties duomenis, t. y. darbo našuma. Šio pobūdžio tyrimams reikia patikimo metodo ar priemones darbininku buvimo vietai nustatyti. Tačiau tokios priemones nera. Šiame tyrime nagrinejami trys vietos nustatymo metodai kaip automatizuotos darbo jegos kontroles priemones: 1) buvimo vietos nustatymo modeliavimas rankiniu būdu; 2) GPS; 3) fotografavimas. Pirmieji du metodai pasirode subjektyvūs, netikslūs ir nepatikimi. Nustatyta, kad trečiasis metodas tinkamas atliekamo tyrimo tikslui. Taikomas klasikinis chronometravimo būdas kartu su vaizdo irašymo metodika, parengta šio tyrimo metu.

A New "Kinetic" Method for Enzyme Analysis Suitable for Automation

1969 ◽  
Vol 15 (6) ◽  
pp. 452-459 ◽  
Author(s):  
Kenneth A Trayser ◽  
David Seligson
Keyword(s):  
Enzyme Activity ◽  
Kinetic Method ◽  
Reaction Rates ◽  
Enzyme Concentration ◽  
Order Reaction ◽  
Enzyme Analysis ◽  
Spectrophotometric Measurement ◽  
Kinetic Measurements ◽  
A Value ◽  
Zero Order Reaction

Abstract A method is proposed for automatic instrumentation of enzyme activity determinations which involve spectrophotometric measurements. The procedure utilizes a kinetic method to produce one instrumental reading that is proportional to enzyme concentration. The single spectrophotometric reading can be processed by analog or digital computation, using the known absorptivity constant of the reactant or product measured, to provide a value for enzyme activity expressed in micromoles of substrate consumed or product formed per unit time per unit volume under the specified conditions. Using the spectrophotometric measurement, one can establish enzyme concentrations based on absolute constants yielding results similar to those obtained by conventional kinetic measurements of zero-order reaction rates which are proportional to enzyme concentration.

scholarly journals Solar active region emergence and flare productivity

2006 ◽  
Vol 2 (14) ◽  
pp. 614-614
Author(s):  
Silvia C. Dalla ◽  
Lyndsay Fletcher ◽  
Nicholas A. Walton
Keyword(s):  
Active Region ◽  
Solar Active Region ◽  
Virtual Observatory ◽  
The Sun ◽  
A Value ◽  
Significant Difference ◽  
Region Emergence ◽  
Two Populations ◽  
East West ◽  
Flare Productivity

AbstractWe use the workflow capabilities of the AstroGrid Virtual Observatory system (<http://www.astrogrid.org>) to analyse the relation between flare productivity and location of Active Region (AR) emergence on the Sun. Specifically, we investigate whether emergence of a new region near existing ones results in increased productivity of the new and/or pre-existing AR. To address this question, we build a series of workflows that perform queries to catalogues of regions and flares, and operations on the results of the queries. There is a strong East-West asymmetry in the location of emergence of new regions. We do not find a significant difference between the flaring rate of paired and isolated regions, when we choose a value of 12° as the cutoff between the two populations.

scholarly journals Real-Time Microscopic Observation of Candida Biofilm Development and Effects Due to Micafungin and Fluconazole

2013 ◽  
Vol 57 (5) ◽  
pp. 2226-2230 ◽  
Author(s):  
Yukihiro Kaneko ◽  
Susumu Miyagawa ◽  
On Takeda ◽  
Masateru Hakariya ◽  
Satoru Matsumoto ◽  
...  
Keyword(s):  
Real Time ◽  
Time Lapse ◽  
Time Data ◽  
Biofilm Growth ◽  
Content Type ◽  
Biofilm Thickness ◽  
Ergosterol Synthesis ◽  
Glucan Synthesis ◽  
Biofilm Development ◽  
Observation Period

ABSTRACTTo understand the process ofCandidabiofilm development and the effects of antifungal agents on biofilms, we analyzed real-time data comprising time-lapse images taken at times separated by brief intervals. The growth rate was calculated by measuring the change of biofilm thickness every hour. For the antifungal study, 5-h-old biofilms ofCandida albicanswere treated with either micafungin (MCFG) or fluconazole (FLCZ). MCFG began to suppress biofilm growth a few minutes after the initiation of the treatment, and this effect was maintained over the course of the observation period. In contrast, the suppressive effects of FLCZ on biofilm growth took longer to manifest: biofilms grew in the first 5 h after treatment, and then their growth was suppressed over the next 10 h, finally producing results similar to those observed with MCFG. MCFG was also involved in the disruption of cells in the biofilms, releasing string-like structures (undefined extracellular component) from the burst hyphae. Thus, MCFG inhibited the detachment of yeast cell clusters from the tips of hyphae. In contrast, FLCZ did not disrupt biofilm cells. MCFG also showed fast antifungal activity againstCandida parapsilosisbiofilms. In conclusion, our results show that inhibition of glucan synthesis due to MCFG contributed not only to fungicidal activity but also to the immediate suppression of biofilm growth, while FLCZ suppressed growth by inhibiting ergosterol synthesis. Therefore, those characteristic differences should be considered when treating clinical biofilm infections.

scholarly journals Hydrosol of Thymbra capitata Is a Highly Efficient Biocide against Salmonella enterica Serovar Typhimurium Biofilms

2016 ◽  
Vol 82 (17) ◽  
pp. 5309-5319 ◽  
Author(s):  
Foteini Karampoula ◽  
Efstathios Giaouris ◽  
Julien Deschamps ◽  
Agapi I. Doulgeraki ◽  
George-John E. Nychas ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Laser Scanning ◽  
High Efficiency ◽  
3D Structure ◽  
Time Lapse ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Planktonic Cells ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTSalmonellais recognized as one of the most significant enteric foodborne bacterial pathogens. In recent years, the resistance of pathogens to biocides and other environmental stresses, especially when they are embedded in biofilm structures, has led to the search for and development of novel antimicrobial strategies capable of displaying both high efficiency and safety. In this direction, the aims of the present work were to evaluate the antimicrobial activity of hydrosol of the Mediterranean spiceThymbracapitataagainst both planktonic and biofilm cells ofSalmonella entericaserovar Typhimurium and to compare its action with that of benzalkonium chloride (BC), a commonly used industrial biocide. In order to achieve this, the disinfectant activity following 6-min treatments was comparatively evaluated for both disinfectants by calculating the concentrations needed to achieve the same log reductions against both types of cells. Their bactericidal effect against biofilm cells was also comparatively determined byin situand real-time visualization of cell inactivation through the use of time-lapse confocal laser scanning microscopy (CLSM). Interestingly, results revealed that hydrosol was almost equally effective against biofilms and planktonic cells, whereas a 200-times-higher concentration of BC was needed to achieve the same effect against biofilm compared to planktonic cells. Similarly, time-lapse CLSM revealed the significant advantage of the hydrosol to easily penetrate within the biofilm structure and quickly kill the cells, despite the three-dimensional (3D) structure ofSalmonellabiofilm.IMPORTANCEThe results of this paper highlight the significant antimicrobial action of a natural compound, hydrosol ofThymbra capitata, against both planktonic and biofilm cells of a common foodborne pathogen. Hydrosol has numerous advantages as a disinfectant of food-contact surfaces. It is an aqueous solution which can easily be rinsed out from surfaces, it does not have the strong smell of the essential oil (EO) and it is a byproduct of the EO distillation procedure without any industrial application until now. Consequently, hydrosol obviously could be of great value to combat biofilms and thus to improve product safety not only for the food industries but probably also for many other industries which experience biofilm-related problems.

scholarly journals Visible Light-Activated Carbon Dots for Inhibiting Biofilm Formation and Inactivating Biofilm-Associated Bacterial Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiuli Dong ◽  
Christopher M. Overton ◽  
Yongan Tang ◽  
Jasmine P. Darby ◽  
Ya-Ping Sun ◽  
...  
Keyword(s):  
Visible Light ◽  
Carbon Dots ◽  
Biofilm Formation ◽  
Chelating Agents ◽  
Early Stage ◽  
Inhibitory Effect ◽  
Bacterial Cells ◽  
Planktonic Cells ◽  
Biofilm Growth ◽  
Time Point

This study aimed to address the significant problems of bacterial biofilms found in medical fields and many industries. It explores the potential of classic photoactive carbon dots (CDots), with 2,2′-(ethylenedioxy)bis (ethylamine) (EDA) for dot surface functionalization (thus, EDA-CDots) for their inhibitory effect on B. subtilis biofilm formation and the inactivation of B. subtilis cells within established biofilm. The EDA-CDots were synthesized by chemical functionalization of selected small carbon nanoparticles with EDA molecules in amidation reactions. The inhibitory efficacy of CDots with visible light against biofilm formation was dependent significantly on the time point when CDots were added; the earlier the CDots were added, the better the inhibitory effect on the biofilm formation. The evaluation of antibacterial action of light-activated EDA-CDots against planktonic B. subtilis cells versus the cells in biofilm indicate that CDots are highly effective for inactivating planktonic cells but barely inactivate cells in established biofilms. However, when coupling with chelating agents (e.g., EDTA) to target the biofilm architecture by breaking or weakening the EPS protection, much enhanced photoinactivation of biofilm-associated cells by CDots was achieved. The study demonstrates the potential of CDots to prevent the initiation of biofilm formation and to inhibit biofilm growth at an early stage. Strategic combination treatment could enhance the effectiveness of photoinactivation by CDots to biofilm-associated cells.

scholarly journals Engineered lactobacilli display anti-biofilm and growth suppressing activities against Pseudomonas aeruginosa

2020 ◽  
Author(s):  
Todd C. Chappell ◽  
Nikhil U. Nair
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lactic Acid ◽  
Biofilm Formation ◽  
Antimicrobial Treatment ◽  
Infection Site ◽  
Planktonic Cells ◽  
Biofilm Growth ◽  
Growth State ◽  
Development Of Resistance ◽  
Pathogen Load

AbstractBiofilms are an emerging target for new therapeutics in the effort to address the continued increase in resistance and tolerance to traditional antimicrobials. In particular, the distinct nature of the biofilm growth state often means that traditional antimicrobials, developed to combat planktonic cells, are ineffective. Biofilm treatments are designed to both reduce pathogen load at an infection site and decrease the development of resistance by rendering the embedded organisms more susceptible to treatment at lower antimicrobial concentrations. In this work, we developed a new antimicrobial treatment modality by characterizing the natural capacity of two lactobacilli, L. plantarum and L. rhamnosus, to inhibit P. aeruginosa growth, biofilm formation, and biofilm viability. We further engineered these lactic acid bacteria (LAB) to secrete enzymes known to degrade P. aeruginosa biofilms and show that our best performing engineered LAB, secreting a pathogen-derived enzyme (PelAhyd), degrades up to 85 % of P. aeruginosa biofilm.

scholarly journals Antimicrobial Resistance in Pseudomonas aeruginosa Biofilms

2021 ◽  
Author(s):  
Dhara Patel ◽  
Palash Sen ◽  
Yin Hlaing ◽  
Michael Boadu ◽  
Bassam Saadeh ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Multidrug Resistance ◽  
Antimicrobial Resistance ◽  
Growth Inhibition ◽  
Biofilm Formation ◽  
Broth Microdilution ◽  
Planktonic Cells ◽  
Biofilm Growth ◽  
Minimal Inhibitory Concentrations ◽  
Dose Dependent

Pseudomonas aeruginosa (PA) is part of a group of common nosocomial pathogens that exhibit multidrug resistance, thus proving to be a significant threat to healthcare. This study analyzes the ability of four commonly used antibiotics to observe eradication of the PA biofilm growth. Ceftazidime (CAZ), Tobramycin (TOB), Ofloxacin (OFLX), Meropenem (MEM), were tested against overnight cultures of PA strain PA01. The minimal inhibitory concentrations (MIC) of planktonic cells for all the four antibiotics were determined using broth microdilution while the minimal bactericidal concentrations (MBCs) were determined by colony count after antibiotic treatment and regrowth. Biofilm growth inhibition was performed by treating cells with antibiotic at the time of inoculation while eradication was determined by adding antibiotics 24 hours after inoculation, allowing mature biofilm formation, followed by the measurement of absorbance. PA planktonic cells exhibited the highest susceptibility to MEM compared to overnight grown PA biofilm which demonstrated resistance to CAZ, complete sensitivity to ofloxacin, and minimal sensitivity to TOB and MEM. PA biofilm displayed dose-dependent sensitivity to TOB, MEM and OFLX, and a significant level of resistance to CAZ during the inhibition phase. However, in the eradication phase, PA showed significant resistance to TOB followed by CAZ while PA biofilm showed sensitivity at higher concentrations of MEM. Our study exhibits that PA strain PA01 is resistant to ceftazidime in both planktonic and biofilm phases. While ofloxacin proved to be the most effective even at lower concentrations when compared with other antibiotics, tobramycin was most effective at higher concentrations for eradicating and inhibiting PA biofilms.

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