Biofilm development in down flow anaerobic fluidised bed reactors under transient conditions

2002 ◽  
Vol 46 (1-2) ◽  
pp. 253-256
Author(s):  
F. Tessele ◽  
G. Englert ◽  
L.O. Monteggia
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fluidised Bed ◽  
Initial Adhesion ◽  
Scale Down ◽  
Synthetic Solution ◽  
Biofilm Development ◽  
Fluidised Bed Reactor ◽  
Biofilm Structure ◽  
Scanning Electron

Biofilm development onto polypropylene particles (<4 mm) was studied in a laboratory-scale down flow anaerobic fluidised bed reactor. The reactor was fed with a synthetic solution containing sucrose and nutrients, and operated at 35°C during 65 days at 44% bed expansion rate and 36 h HRT. Scanning electron microscopy (SEM) monitored the biofilm development. Initial adhesion occurred within the first 6 hours and after day 44 biofilm structure was complete. The presence of attached cells morphologically similar to Methanotrix bacilli and Methanosarcina sp. was observed by Scanning Electron Microscopy (SEM). The biofilm and the carrier surface roughness were measured by atomic force microscopy (AFM) and yielded 9.1 and 75 nm respectively. Results also showed good correlation between the SEM characterisation and the conventional anaerobic reactor parameters.

scholarly journals Morphological and proteomic analysis of early stage air–liquid interface biofilm formation in Mycobacterium smegmatis

Microbiology ◽  
2014 ◽  
Vol 160 (7) ◽  
pp. 1346-1356 ◽  
Author(s):  
Zuzana Sochorová ◽  
Denisa Petráčková ◽  
Barbora Sitařová ◽  
Karolína Buriánková ◽  
Silvia Bezoušková ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Wall ◽  
Mycobacterium Smegmatis ◽  
Expression Profiles ◽  
Liquid Interface ◽  
Pellicle Formation ◽  
Biofilm Development ◽  
Air Liquid Interface ◽  
Scanning Electron

We studied the early stages of pellicle formation by Mycobacterium smegmatis on the surface of a liquid medium [air–liquid interface (A–L)]. Using optical and scanning electron microscopy, we showed the formation of a compact biofilm pellicle from micro-colonies over a period of 8–30 h. The cells in the pellicle changed size and cell division pattern during this period. Based on our findings, we created a model of M. smegmatis A–L early pellicle formation showing the coordinate growth of cells in the micro-colonies and in the homogeneous film between them, where the accessibility to oxygen and nutrients is different. A proteomic approach utilizing high-resolution two-dimensional gel electrophoresis, in combination with mass spectrometry-based protein identification, was used to analyse the protein expression profiles of the different morphological stages of the pellicle. The proteins identified formed four expression groups; the most interesting of these groups contained the proteins with highest expression in the biofilm development phase, when the floating micro-colonies containing long and more robust cells associate into flocs and start to form a compact pellicle. The majority of these proteins, including GroEL1, are involved in cell wall synthesis or modification, mostly through the involvement of mycolic acid biosynthesis, and their expression maxima correlated with the changes in cell size and the rigidity of the bacterial cell wall observed by scanning electron microscopy.

scholarly journals Evaluation of two fixation techniques for direct observation of biofilm formation of Bacillus subtilis in situ, on Congo red agar, using scanning electron microscopy

2020 ◽  
Vol 13 (6) ◽  
pp. 1133-1137
Author(s):  
Nadia Mahmoud Tawfiq Jebril
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Direct Observation ◽  
Congo Red ◽  
Fixation Method ◽  
Fixation Technique ◽  
Fixation Techniques ◽  
Biofilm Development ◽  
Scanning Electron

Background and Aim: Direct observation, scanning electron microscopy (SEM) is a common method used for the observations of biofilms. N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide) (EDC) fixation method has proven to be a valuable fixation method in the observation of these biofilms. Still, it entails a method of biofilm fixation that can damage slim structures, leading to the impossible observation of biofilm development. In contrast, alcian blue and lysine (ABL) fixation technique appears more glycocalyx of biofilm, fully preserved samples, which may provide much insight into the development of B. subtilis biofilms. Materials and Methods: Here, the evaluation of the fixation of ABL technique for the study of B. subtilis biofilms was carried out in situ, on Congo red agar. In doing so, the comparison to commonly use conventional EDC technique for sample fixation, and observation was carried out. Observations were based on SEM over 30 samples. Results: Overall, ABL technique provided excellent observation of biofilms formed in situ, on Congo red agar, and revealed slime structures, which have not been observed, much in standard EDC fixation or earlier in other studies of these biofilms in B. subtilis. Conclusion: This study reported the appropriate use of ABL in the fixation technique for the preservation of biofilm of B. subtilis.

Novel composite photocatalyst made of TiO2 nanoparticles

2010 ◽  
Vol 61 (4) ◽  
pp. 903-909 ◽  
Author(s):  
A. Vega ◽  
G. E. Imoberdorf ◽  
M. Keshmir ◽  
M. Mohseni
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tio2 Nanoparticles ◽  
Fluidised Bed ◽  
X Ray Diffraction ◽  
Complete Model ◽  
Composite Photocatalyst ◽  
X Ray ◽  
Photocatalytic Reactors ◽  
Scanning Electron

A novel photocatalyst based on TiO2 nanoparticles was developed for application in fluidised bed photocatalytic reactors for water treatment. The mechanically robust photocatalyst consists of composite spheres made of TiO2 nanoparticles and TiO2 commercial powder. X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area analysis (BET) were used to characterise the catalyst. The photocatalytic activity was evaluated using model pesticide micro-pollutant. A complete model comprised of radiation, kinetic, and reactor bed models was also developed, allowing for detailed analysis of the photoreactor.

scholarly journals Candida albicans enhances meropenem tolerance of Pseudomonas aeruginosa in a dual-species biofilm

2019 ◽  
Vol 75 (4) ◽  
pp. 925-935 ◽  
Author(s):  
Farhana Alam ◽  
Dominic Catlow ◽  
Alessandro Di Maio ◽  
Jessica M A Blair ◽  
Rebecca A Hall
Keyword(s):  
Electron Microscopy ◽  
Cystic Fibrosis ◽  
Scanning Electron Microscopy ◽  
Extracellular Matrix ◽  
Pseudomonas Aeruginosa ◽  
Candida Albicans ◽  
Medical Devices ◽  
Fungal Infections ◽  
Biofilm Structure ◽  
Scanning Electron

Abstract Background Pseudomonas aeruginosa is an opportunistic bacterium that infects the airways of cystic fibrosis patients, surfaces of surgical and burn wounds, and indwelling medical devices. Patients are prone to secondary fungal infections, with Candida albicans being commonly co-isolated with P. aeruginosa. Both P. aeruginosa and C. albicans are able to form extensive biofilms on the surfaces of mucosa and medical devices. Objectives To determine whether the presence of C. albicans enhances antibiotic tolerance of P. aeruginosa in a dual-species biofilm. Methods Single- and dual-species biofilms were established in microtitre plates and the survival of each species was measured following treatment with clinically relevant antibiotics. Scanning electron microscopy and confocal microscopy were used to visualize biofilm structure. Results C. albicans enhances P. aeruginosa biofilm tolerance to meropenem at the clinically relevant concentration of 5 mg/L. This effect is specific to biofilm cultures and is dependent upon C. albicans extracellular matrix polysaccharides, mannan and glucan, with C. albicans cells deficient in glycosylation structures not enhancing P. aeruginosa tolerance to meropenem. Conclusions We propose that fungal mannan and glucan secreted into the extracellular matrix of P. aeruginosa/C. albicans dual-species biofilms play a central role in enhancing P. aeruginosa tolerance to meropenem, which has direct implications for the treatment of coinfected patients.

scholarly journals Vulnerability of Pathogenic Biofilms to Micavibrio aeruginosavorus

2006 ◽  
Vol 73 (2) ◽  
pp. 605-614 ◽  
Author(s):  
Daniel Kadouri ◽  
Nel C. Venzon ◽  
George A. O'Toole
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pseudomonas Aeruginosa ◽  
Burkholderia Cepacia ◽  
Flow Cell ◽  
Gram Negative ◽  
Fold Reduction ◽  
Biofilm Structure ◽  
Pathogenic Biofilms ◽  
Scanning Electron

ABSTRACT The host specificity of the gram-negative exoparasitic predatory bacterium Micavibrio aeruginosavorus was examined. M. aeruginosavorus preyed on Pseudomonas aeruginosa, as previously reported, as well as Burkholderia cepacia, Klebsiella pneumoniae, and numerous clinical isolates of these species. In a static assay, a reduction in biofilm biomass was observed as early as 3 hours after exposure to M. aeruginosavorus, and an ∼100-fold reduction in biofilm cell viability was detected following a 24-h exposure to the predator. We observed that an initial titer of Micavibrio as low as 10 PFU/well or a time of exposure to the predator as short as 30 min was sufficient to reduce a P. aeruginosa biofilm. The ability of Micavibrio to reduce an existing biofilm was confirmed by scanning electron microscopy. In static and flow cell experiments, M. aeruginosavorus was able to modify the overall P. aeruginosa biofilm structure and markedly decreased the viability of P. aeruginosa. The altered biofilm structure was likely caused by an increase in cell-cell interactions brought about by the presence of the predator or active predation. We also conducted a screen to identify genes important for P. aeruginosa-Micavibrio interaction, but no candidates were isolated among the ∼10,000 mutants tested.

scholarly journals Monitoring Candida parapsilosis and Staphylococcus epidermidis Biofilms by a Combination of Scanning Electron Microscopy and Raman Spectroscopy

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4089 ◽  
Author(s):  
Kamila Hrubanova ◽  
Vladislav Krzyzanek ◽  
Jana Nebesarova ◽  
Filip Ruzicka ◽  
Zdenek Pilat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Composition ◽  
Sample Preparation ◽  
Staphylococcus Epidermidis ◽  
Candida Parapsilosis ◽  
Freeze Fracture ◽  
Biofilm Structure ◽  
Scanning Electron

The biofilm-forming microbial species Candida parapsilosis and Staphylococcus epidermidis have been recently linked to serious infections associated with implanted medical devices. We studied microbial biofilms by high resolution scanning electron microscopy (SEM), which allowed us to visualize the biofilm structure, including the distribution of cells inside the extracellular matrix and the areas of surface adhesion. We compared classical SEM (chemically fixed samples) with cryogenic SEM, which employs physical sample preparation based on plunging the sample into various liquid cryogens, as well as high-pressure freezing (HPF). For imaging the biofilm interior, we applied the freeze-fracture technique. In this study, we show that the different means of sample preparation have a fundamental influence on the observed biofilm structure. We complemented the SEM observations with Raman spectroscopic analysis, which allowed us to assess the time-dependent chemical composition changes of the biofilm in vivo. We identified the individual spectral peaks of the biomolecules present in the biofilm and we employed principal component analysis (PCA) to follow the temporal development of the chemical composition.

Green Synthesis of Silver Nanoparticles for Control of Biodeterioration

2014 ◽  
Vol 1618 ◽  
pp. 241-246 ◽  
Author(s):  
M.A. Martínez Gómez ◽  
M.C. González Chávez ◽  
J.C. Mendoza Hernández ◽  
R. Carrillo González
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Silver Nanoparticles ◽  
Cultural Heritage ◽  
Green Synthesis ◽  
Biological Synthesis ◽  
Vis Spectroscopy ◽  
Heritage Buildings ◽  
Biofilm Development ◽  
Scanning Electron

ABSTRACTChemical and biological deterioration of surfaces of historic constructions is one of the main causes of destruction of cultural heritage buildings. Effective techniques are searched in order to control the biofilm development of cultural heritage without damaging the environment. Nanotechnology is an emerging option with several applications, including those for improving stability and corrosion resistance in surfaces. Production of nanomaterials from organic nature or green synthesis offers ecological advantages such as low environmental impact. This paper proposes the use of silver nanoparticles of biological synthesis as an alternative for control of microorganisms that cause biodeterioration. The present study highlights the effect of these nanoparticles in the inhibition of bacterial growth. These particles were produced by biological synthesis with Tecoma stans L. extracts. Their characterization included analysis UV / Vis spectroscopy, scanning electron microscopy (SEM) and particle size distribution.

Scanning electron microscopy of biofilm development in anaerobic fixed-bed reactors: Influence of the inoculum

1994 ◽  
Vol 16 (3) ◽  
pp. 315-320 ◽  
Author(s):  
Gerhard Zellner ◽  
Hans Diekmann ◽  
Ute Austermann-Haun ◽  
Carl Franz Seyfried
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fixed Bed ◽  
Fixed Bed Reactors ◽  
Biofilm Development ◽  
Scanning Electron

Pathogenesis of Human Hair Defects

1974 ◽  
Vol 32 ◽  
pp. 12-13
Author(s):  
P.S. Porter ◽  
T. Aoyagi ◽  
R. Matta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Hair ◽  
Standard Techniques ◽  
Scanning Electron

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.

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