scholarly journals Mosaic-CLSM Assessment of Bacterial Spatial Distribution in Cosmetic Matrices According to Matrix Viscosity and Bacterial Hydrophobicity

Cosmetics ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 32
Author(s):  
Samia Almoughrabie ◽  
Chrisse Ngari ◽  
Romain Briandet ◽  
Valérie Poulet ◽  
Florence Dubois-Brissonnet
Keyword(s):  
Spatial Distribution ◽  
Laser Scanning ◽  
Rapid Assessment ◽  
Challenge Test ◽  
Surface Hydrophobicity ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Surface ◽  
Bacterial Hydrophobicity ◽  
The Impact

The reliability of the challenge test depends, among other parameters, on the spatial distribution of microorganisms in the matrix. The present study aims to quickly identify factors that are susceptible to impair a uniform distribution of inoculated bacteria in cosmetic matrices in this context. We used mosaic confocal laser scanning microscopy (M-CLSM) to obtain rapid assessment of the impact of the composition and viscosity of cosmetic matrices on S. aureus spatial distribution. Several models of cosmetic matrices were formulated with different concentrations of two thickeners and were inoculated with three S. aureus strains having different levels of hydrophobicity. The spatial distribution of S. aureus in each matrix was evaluated according to the frequency distribution of the fluorescence values of at least 1350 CLSM images. We showed that, whatever the thickener used, an increasingly concentration of thickener results in increasingly bacterial clustered distribution. Moreover, higher bacterial hydrophobicity also resulted in a more clustered spatial distribution. In conclusion, CLSM-based method allows a rapid characterization of bacterial spatial distribution in complex emulsified systems. Both matrix viscosity and bacterial surface hydrophobicity affect the bacterial spatial distribution which can have an impact on the reliability of bacterial enumeration during challenge test.

Confocal and SEM imaging to demonstrate food pathogen- biofilm biocontrol by pyocyanin from Pseudomonas aeruginosa BTRY1

2016 ◽  
Vol 6 (01) ◽  
pp. 5218
Author(s):  
Laxmi Mohandas ◽  
Anju T. R. ◽  
Sarita G. Bhat*
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Antibiofilm Activity ◽  
Opportunistic Pathogens ◽  
Redox Active ◽  
Sem Imaging ◽  
The Impact

An assortment of redox-active phenazine compounds like pyocyanin with their characteristic blue-green colour are synthesized by Pseudomonas aeruginosa, Gram-negative opportunistic pathogens, which are also considered one of the most commercially valuable microorganisms. In this study, pyocyanin from Pseudomonas aeruginosa BTRY1 from food sample was assessed for its antibiofilm activity by micro titer plate assay against strong biofilm producers belonging to the genera Bacillus, Staphylococcus, Brevibacterium and Micrococcus. Pyocyanin inhibited biofilm activity in very minute concentrations. This was also confirmed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). Both SEM and CLSM helped to visualize the biocontrol of biofilm formation by eight pathogens. The imaging and quantification by CLSM also established the impact of pyocyanin on biofilm-biocontrol mainly in the food industry.

scholarly journals The effect of the dispersion of microfibrillated cellulose on the mechanical properties of melt-compounded polypropylene–polyethylene copolymer

Cellulose ◽  
2019 ◽  
Vol 26 (18) ◽  
pp. 9645-9659 ◽  
Author(s):  
Caterina Palange ◽  
Marcus A. Johns ◽  
David J. Scurr ◽  
Jonathan S. Phipps ◽  
Stephen J. Eichhorn
Keyword(s):  
Tannic Acid ◽  
Laser Scanning ◽  
Secondary Ion Mass Spectrometry ◽  
High Surface ◽  
Microfibrillated Cellulose ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Cellulose Content ◽  
Reinforced Composites ◽  
The Impact

Abstract Microfibrillated cellulose (MFC) is a highly expanded, high surface area networked form of cellulose-based reinforcement. Due to the poor compatibility of cellulose with most common apolar thermoplastic matrices, the production of cellulose-reinforced composites in industry is currently limited to polar materials. In this study, a facile water-based chemistry, based on the reaction of MFC with tannic acid and subsequent functionalisation with an alkyl amine, is used to render the surface of the MFC fibrils hydrophobic and enhance the dispersion of the cellulose-based filler into an apolar thermoplastic matrix. The level of dispersion of the compatibilized MFC reinforced composites was evaluated using Time of Flight Secondary Ion Mass Spectrometry and multi-channel Spectral Confocal Laser Scanning Microscopy. The agglomeration of cellulosic filler within the composites was reduced by functionalising the surface of the MFC fibrils with tannic acid and octadecylamine. The resulting composites exhibited an increase in modulus at a high cellulose content. Despite the dispersion of a large portion of the functionalised filler, the presence of some remaining aggregates affected the impact properties of the composites produced.

A Novel Synonymous Variant in the AVP Gene Associated with Autosomal Dominant Familial Neurohypophyseal Diabetes Insipidus Causes Partial RNA Missplicing

2018 ◽  
Vol 107 (2) ◽  
pp. 167-180
Author(s):  
Helene Kvistgaard ◽  
Jane H. Christensen ◽  
Jan-Ove Johansson ◽  
Niels Gregersen ◽  
Charlotte Siggaard Rittig ◽  
...  
Keyword(s):  
Diabetes Insipidus ◽  
Laser Scanning ◽  
Dna Analysis ◽  
Autosomal Dominant ◽  
Challenge Test ◽  
Family Members ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Synonymous Variant ◽  
Avp Gene

Objective: Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI) is characterized by severe polyuria and polydipsia and is caused by variations in the gene encoding the AVP prohormone. This study aimed to ascertain a correct diagnosis, to identify the underlying genetic cause of adFNDI in a Swedish family, and to test the hypothesis that the identified synonymous exonic variant in the AVP gene (c.324G>A) causes missplicing and endoplasmic reticulum (ER) retention of the prohormone. Design/Patients: Three affected family members were admitted for fluid deprivation test and dDAVP (1-deamino-8-d-arginine-vasopressin) challenge test. Direct sequencing of the AVP gene was performed in the affected subjects, and genotyping of the identified variant was performed in family members. The variant was examined by expression of AVP minigenes containing the entire coding regions as well as intron 2 of AVP. Methods/Results: Clinical tests revealed significant phenotypical variation with both complete and partial adFNDI phenotype. DNA analysis revealed a synonymous c.324G>A substitution in one allele of the AVP gene in affected family members only. Cellular studies revealed both normally spliced and misspliced pre-mRNA in cells transfected with the AVP c.324G>A minigene. Confocal laser scanning microscopy showed collective localization of the variant prohormone to ER and vesicular structures at the tip of cellular processes. Conclusion: We identified a synonymous variant affecting the second nucleotide of exon 3 in the AVP gene (c.324G>A) in a family in which adFNDI segregates. Notably, we showed that this variant causes partial missplicing of pre-mRNA, resulting in accumulation of the variant prohormone in ER. Our study suggests that even a small amount of aberrant mRNA might be sufficient to disturb cellular function, resulting in adFNDI.

scholarly journals Effects of Fine Particulate Matter onPseudomonas aeruginosaAdhesion and Biofilm FormationIn Vitro

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Seon Hee Woo ◽  
Sang Moog Lee ◽  
Ki Cheol Park ◽  
Gyeong Nam Park ◽  
Byeolnimhee Cho ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Epithelial Cells ◽  
Biofilm Formation ◽  
Protein Concentration ◽  
Fine Particulate Matter ◽  
Surface Hydrophobicity ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Surface ◽  
Fine Particulate

Respiratory infections ofPseudomonas aeruginosaare a major cause of mortality and morbidity for hospitalized patients. Fine particulate matter (FPM) is known to have interactions with some bacterial infection in the respiratory system. In this report, we investigate the effect of different concentration of FPM onP. aeruginosaattachment and biofilm formation usingin vitrocell culture systems.P. aeruginosawere cultured to form mature biofilms on hydroxyapatite-coated peg and the number of bacteria in the biofilms was enumerated. Morphology of biofilm was imaged with scanning electron microscopy and confocal laser scanning microscopy. Bacterial affinity change to the cell membrane was evaluated with attached colony counting and fluorescence microscopy images. Alteration of bacterial surface hydrophobicity and S100A4 protein concentration were explored as mechanisms ofP. aeruginosaadhesion to human cells. There were a concentration-dependent increase of thickness and surface roughness of biofilm mass.P. aeruginosaadherence to respiratory epithelial cells was increased after FPM treatment. Bacterial surface hydrophobicity and S1000A4 protein concentration were increased with proportionally the dose of FPM in media. FPM in the airway could enhance both the adhesion ofP. aeruginosato epithelial cells and biofilm formation. Bacterial surface hydrophobicity and human cell plasma membrane injury are associated with binding ofP. aeruginosaon airway epithelial cells and biofilm formation.

Considerations in the use of fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy to characterize rumen methanogens and define their spatial distributions

2015 ◽  
Vol 61 (6) ◽  
pp. 417-428 ◽  
Author(s):  
Edith R. Valle ◽  
Gemma Henderson ◽  
Peter H. Janssen ◽  
Faith Cox ◽  
Trevor W. Alexander ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
In Situ Hybridization ◽  
16S Rrna ◽  
Fluorescence In Situ Hybridization ◽  
Confocal Laser Scanning Microscopy ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Confocal Laser

In this study, methanogen-specific coenzyme F420autofluorescence and confocal laser scanning microscopy were used to identify rumen methanogens and define their spatial distribution in free-living, biofilm-, and protozoa-associated microenvironments. Fluorescence in situ hybridization (FISH) with temperature-controlled hybridization was used in an attempt to describe methanogen diversity. A heat pretreatment (65 °C, 1 h) was found to be a noninvasive method to increase probe access to methanogen RNA targets. Despite efforts to optimize FISH, 16S rRNA methanogen-specific probes, including Arch915, bound to some cells that lacked F420, possibly identifying uncharacterized Methanomassiliicoccales or reflecting nonspecific binding to other members of the rumen bacterial community. A probe targeting RNA from the methanogenesis-specific methyl coenzyme M reductase (mcr) gene was shown to detect cultured Methanosarcina cells with signal intensities comparable to those of 16S rRNA probes. However, the probe failed to hybridize with the majority of F420-emitting rumen methanogens, possibly because of differences in cell wall permeability among methanogen species. Methanogens were shown to integrate into microbial biofilms and to exist as ecto- and endosymbionts with rumen protozoa. Characterizing rumen methanogens and defining their spatial distribution may provide insight into mitigation strategies for ruminal methanogenesis.

scholarly journals Electrochemical and surface analytical techniques applied to microbiologically influenced corrosion investigation

2018 ◽  
Vol 36 (4) ◽  
pp. 349-363 ◽  
Author(s):  
László Trif ◽  
Abdul Shaban ◽  
Judit Telegdi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Laser Scanning ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Analytical Techniques ◽  
Laser Scanning Microscopy ◽  
Microbiologically Influenced Corrosion ◽  
Microbial Consortia ◽  
Confocal Laser ◽  
The Impact

AbstractSuitable application of techniques for detection and monitoring of microbiologically influenced corrosion (MIC) is crucial for understanding the mechanisms of the interactions and for selecting inhibition and control approaches. This paper presents a review of the application of electrochemical and surface analytical techniques in studying the MIC process of metals and their alloys. Conventional electrochemical techniques, such as corrosion potential (Ecorr), redox potential, dual-cell technique, polarization curves, electrochemical impedance spectroscopy (EIS), electrochemical noise (EN) analysis, and microelectrode techniques, are discussed, with examples of their use in various MIC studies. Electrochemical quartz crystal microbalance, which is newly used in MIC study, is also discussed. Microscopic techniques [scanning electron microscopy (SEM), environmental SEM (ESEM), atomic force microscopy (AFM), confocal laser microscopy (CLM), confocal laser scanning microscopy (CLSM), confocal Raman microscopy] and spectroscopic analytical methods [Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS)] are also highlighted. This review highlights the heterogeneous characteristics of microbial consortia and use of special techniques to study their probable effects on the metal substrata. The aim of this review is to motivate using a combination of new procedures for research and practical measurement and calculation of the impact of MIC and biofilms on metals and their alloys.

scholarly journals Genetic Features of Resident Biofilms Determine Attachment of Listeria monocytogenes

2009 ◽  
Vol 75 (24) ◽  
pp. 7814-7821 ◽  
Author(s):  
Olivier Habimana ◽  
Mickael Meyrand ◽  
Thierry Meylheuc ◽  
Saulius Kulakauskas ◽  
Romain Briandet
Keyword(s):  
Listeria Monocytogenes ◽  
Laser Scanning ◽  
Time Course ◽  
Surface Hydrophobicity ◽  
Flow Cell ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Microscopy Imaging ◽  
Initial Fixation ◽  
Genetic Features

ABSTRACT Planktonic Listeria monocytogenes cells in food-processing environments tend most frequently to adhere to solid surfaces. Under these conditions, they are likely to encounter resident biofilms rather than a raw solid surface. Although metabolic interactions between L. monocytogenes and resident microflora have been widely studied, little is known about the biofilm properties that influence the initial fixation of L. monocytogenes to the biofilm interface. To study these properties, we created a set of model resident Lactococcus lactis biofilms with various architectures, types of matrices, and individual cell surface properties. This was achieved using cell wall mutants that affect bacterial chain formation, exopolysaccharide (EPS) synthesis and surface hydrophobicity. The dynamics of the formation of these biofilm structures were analyzed in flow cell chambers using in situ time course confocal laser scanning microscopy imaging. All the L. lactis biofilms tested reduced the initial immobilization of L. monocytogenes compared to the glass substratum of the flow cell. Significant differences were seen in L. monocytogenes settlement as a function of the genetic background of resident lactococcal biofilm cells. In particular, biofilms of the L. lactis chain-forming mutant resulted in a marked increase in L. monocytogenes settlement, while biofilms of the EPS-secreting mutant efficiently prevented pathogen fixation. These results offer new insights into the role of resident biofilms in governing the settlement of pathogens on food chain surfaces and could be of relevance in the field of food safety controls.

scholarly journals Optimizing CNT Loading in Antimicrobial Composites for Urinary Tract Application

2021 ◽  
Vol 11 (9) ◽  
pp. 4038
Author(s):  
Marisa Gomes ◽  
Luciana C. Gomes ◽  
Rita Teixeira-Santos ◽  
Manuel F. R. Pereira ◽  
Olívia S. G. P. Soares ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Laser Scanning ◽  
Antimicrobial Properties ◽  
Surface Hydrophobicity ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Coating Materials ◽  
Biofilm Thickness ◽  
Angle Measurements ◽  
Antifouling Coatings

Several methodologies have been implemented with the intent of preventing or reducing the formation of biofilms on indwelling urinary devices. The use of carbon nanotubes (CNTs) in the biomedical field has been increasing, particularly in the production of antimicrobial and antifouling coatings. Despite their proven antimicrobial properties, their use as coating materials for urinary tract devices (UTDs) is still poorly documented. In the present work, CNT/poly(dimethylsiloxane) (PDMS) composite materials containing different CNT loadings were prepared and further tested against Escherichia coli under conditions prevailing in UTDs. Besides CNT loading optimization, textural modifications were also introduced on the surface of CNTs to improve the antibiofilm pro-perties of the final composites. Material characterization included the textural evaluation of CNTs and the assessment of surface morphology by scanning electron microscopy, while the surface hydrophobicity was determined by contact angle measurements. Biofilm analysis was performed by determining the number of culturable and total cells and by confocal laser scanning microscopy. Results revealed that, by filling the PDMS matrix with 3 wt% CNT loading, a significant reduction in cell culturability (39%) can be achieved compared to PDMS. Additionally, the textural modifications induced by ball-milling treatment proved to be effective on the inhibition of biofilm formation, reducing the amount of biofilm per surface area, biofilm thickness and surface coverage in 31, 47 and 27%, respectively (compared to surfaces where CNTs were not ball-milled).

scholarly journals Pili and other surface proteins influence the structure and the nanomechanical properties of Lactococcus lactis biofilms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ibrahima Drame ◽  
Christine Lafforgue ◽  
Cecile Formosa-Dague ◽  
Marie-Pierre Chapot-Chartier ◽  
Jean-Christophe Piard ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Laser Scanning ◽  
Binding Proteins ◽  
Binding Protein ◽  
Young Modulus ◽  
Surface Proteins ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
The Impact

AbstractLactic acid bacteria, in particular Lactococcus lactis, are widely used in the food industry, for the control and/or the protection of the manufacturing processes of fermented food. While L. lactis has been reported to form compact and uniform biofilms it was recently shown that certain strains able to display pili at their surface form more complex biofilms exhibiting heterogeneous and aerial structures. As the impact of those biofilm structures on the biomechanical properties of the biofilms is poorly understood, these were investigated using AFM force spectroscopy and imaging. Three types of strains were used i.e., a control strain devoid of pili and surface mucus-binding protein, a strain displaying pili but no mucus-binding proteins and a strain displaying both pili and a mucus-binding protein. To identify potential correlations between the nanomechanical measurements and the biofilm architecture, 24-h old biofilms were characterized by confocal laser scanning microscopy. Globally the strains devoid of pili displayed smoother and stiffer biofilms (Young Modulus of 4–100 kPa) than those of piliated strains (Young Modulus around 0.04–0.1 kPa). Additional display of a mucus-binding protein did not affect the biofilm stiffness but made the biofilm smoother and more compact. Finally, we demonstrated the role of pili in the biofilm cohesiveness by monitoring the homotypic adhesion of bacteria to the biofilm surface. These results will help to understand the role of pili and mucus-binding proteins withstanding external forces.

scholarly journals Protozoan impact on bacterial biofilm formation

2010 ◽  
Vol 47 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Krzysztof Rychert ◽  
Thomas Neu
Keyword(s):  
Activated Sludge ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Grazing Pressure ◽  
Bacterial Biofilm ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Protozoan Community ◽  
Biofilm Development ◽  
The Impact

Protozoan impact on bacterial biofilm formationConfocal laser scanning microscopy in combination with digital image analysis was used to assess the impact of protozoa on bacterial colonisation of surfaces. Bacterial biofilms were developed from activated sludge in microscope flow cells and were exposed to the grazing pressure of protozoa. The protozoan community from healthy activated sludge and a culture of flagellateBodo saltanswere used as grazers. Experiments comprised 48-h incubations in 3 treatment variants: bacteria with protozoa, bacteria with protozoa added after some time and bacteria without protozoa. When necessary, the elimination of protozoa from the inoculum was carried out with cycloheximide and NiSO4. Experiments demonstrated that protozoa from healthy activated sludge initially disturbed the biofilm development but later they could stimulate its growth. Similar results could be established in the experiment withBodo saltans(inoculum: 1000 cells/ml), however differences were not statistically significant. The finding that protozoa support biofilm development during specific stages may be relevant for biofilm studies with mixed environmental biofilm communities.

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