Vancomycin sorption on activated sludge Gram+ bacteria rather than on EPS; 3D Confocal Laser Scanning Microscopy time-lapse imaging

AbstractThe purpose of this study was to investigate thein vitrobiocompatibility of two dental composites (namely A and B) with similar chemical composition used for direct restoration using three-dimensional confocal laser scanning microscopy (CLSM) time-lapse imaging. Time-lapse imaging was performed on cultured human HGF-1 fibroblast-like cells after staining using Live/Dead®. Image analysis showed a higher mortality rate in the presence of composite A than composite B. The viability rate decreased in a time-dependent manner during the 5 h of exposure. Morphological alterations were associated with toxic effects; cells were enlarged and more rounded in the presence of composite A as shown by F-actin and cell nuclei staining. Resazurin assay was used to confirm the active potential of composites in cell metabolism; results showed severe cytotoxic effects in the presence of both no light-curing composites after 24 h of direct contact. However, extracts of polymerized composites induced a moderate decrease in cell metabolism after the same incubation period. Composite B was significantly better tolerated than composite A at all investigated end points and all time points. The finding confirmed that the used CLSM method was sufficiently sensitive to differentiate the biocompatibility behavior of two composites based on similar methacrylate monomers.

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Evaluation of the extracellular polymeric substances by confocal laser scanning microscopy in conventional activated sludge and advanced membrane bioreactors treating hospital wastewater

Water Science & Technology ◽

10.2166/wst.2014.141 ◽

2014 ◽

Vol 69 (11) ◽

pp. 2287-2294 ◽

Cited By ~ 5

Author(s):

Mousaab Alrhmoun ◽

Claire Carrion ◽

Magali Casellas ◽

Christophe Dagot

Keyword(s):

Activated Sludge ◽

Confocal Laser Scanning Microscopy ◽

Laser Scanning ◽

Extracellular Polymeric Substances ◽

Membrane Bioreactors ◽

Laser Scanning Microscopy ◽

Confocal Laser Scanning ◽

Scanning Microscopy ◽

Confocal Laser ◽

Conventional Activated Sludge

Confocal laser scanning microscopy (CLSM) combined with fluorescent viability indicators, was used in this study to investigate the impact of hospital wastewaters on floc structure and composition. In this work, three pilot-scale projects, two membrane bioreactors (MBRs) with a submerged or external membrane bioreactor and a conventional activated sludge, were installed and operated for 65 days. They were fed with an influent sampled directly from the hospital drainage system, which contained micropollutant concentrations ranging from ng/L to mg/L. Samples of flocs were observed using CLSM to characterize the extracellular polymeric substances (EPS) stained with concanavalin A–tetra methylrhodamine and fluorescein isothiocyanate solution and combined with a fluorescent viability indicator (Baclight® Bacterial Viability Kit, Molecular Probes), allowing visualization of isolated stained cells in the three-dimensional structure of flocs (damaged or not). The results of CLSM of the sludge composition were compared with classical biochemical analysis of EPS made through a thermal extraction method. The results showed a good relation between these analyses and the statistical treatment of microscopic pictures.

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