Search results for "Biofilms"
showing 10 items of 176 documents
The influence of solid retention time on IFAS-MBR systems: analysis of system behavior.
2018
A University of Cape Town Integrated Fixed-Film Activated Sludge Membrane Bioreactor (UCT-IFAS-MBR) pilot plant was operated at different values of the sludge retention time (SRT). Three SRTs were investigated at different durations: indefinitely, 30 and 15 days. The organic carbon, nitrogen and phosphorus removal, kinetic/stoichiometric parameters, membrane fouling tendency and sludge filtration properties were assessed. The findings showed that by decreasing the SRT, the pilot plant could maintain excellent carbon removal efficiencies throughout the experiments. In contrast, the biological carbon removal showed a slight nitrification and was slightly affected by the decrease of the SRT, s…
Engineering Bacteria to Form a Biofilm and Induce Clumping in Caenorhabditis elegans
2014
Bacteria are needed for a vast range of biotechnological processes, which they carry out either as pure cultures or in association with other bacteria and/or fungi. The potential of bacteria as biofactories is hampered, though, by their limited mobility in solid or semisolid media such as agricultural or domestic waste. This work represents an attempt toward overcoming this limitation by associating bacterial biotechnological properties with the transport ability of the nematode Caenorhabditis elegans. We report here biofilm formation on C. elegans by engineered Escherichia coli expressing a Xhenorhabdus nematophila adhesion operon and induction of nematode social feeding behavior (clumping…
Synthesis and anti-staphylococcal activity of new 4-diazopyrazole derivatives.
2012
Abstract Several new 4-diazopyrazole derivatives 6a – g and 9a – c were obtained by the reaction of 1-(R-substituted-phenyl)-3-(1,3-dimethyl-1 H -pyrazol-5-yl)ureas 5a – g and N -(1,3-dimethyl-1 H -pyrazol-5-yl)-2-(R-substituted-phenyl)acetamides 8a – c respectively with a sevenfold excess of nitrous acid in acetic acid solution. The compounds were assayed for their activity against the Staphylococcus aureus reference strains ATCC 25923, ATCC 29213 and ATCC 6538, as well as six veterinary strains. The best anti-staphylococcal profile was showed by [(R-substituted-phenyl)acetyl](4-diazonio-1,3-dimethyl-1 H -pyrazol-5-yl)azanides 9a , c . Compound 9c was also able at 3.1 μg mL −1 to inhibit o…
Shedding light on biogas: Phototrophic biofilms in anaerobic digesters hold potential for improved biogas production
2019
Conventional anaerobic digesters intended for the production of biogas usually operate in complete darkness. Therefore, little is known about the effect of light on their microbial communities. In the present work, 16S rRNA gene amplicon Nanopore sequencing and shotgun metagenomic sequencing were used to study the taxonomic and functional structure of the microbial community forming a biofilm on the inner wall of a laboratory-scale transparent anaerobic biodigester illuminated with natural sunlight. The biofilm was composed of microorganisms involved in the four metabolic processes needed for biogas production, and it was surprisingly rich in Rhodopseudomonas faecalis, a versatile bacterium…
Bifunctional dentifrice: Amorphous polyphosphate a regeneratively active sealant with potent anti- Streptococcus mutans activity
2017
Abstract Objective In this study we demonstrate that inorganic polyphosphate (polyP) exhibits a dual protective effect on teeth: it elicits a strong antibacterial effect against the cariogenic bacterium Streptococcus mutans and, in form of amorphous calcium polyP microparticles (size of 100–400 nm), it efficiently reseals cracks/fissures in the tooth enamel and dentin. Methods Three different formulations of amorphous polyP microparticles (Ca-polyP, Zn-polyP and Sr-polyP) were prepared. Results Among the different polyP microparticles tested, the Ca-polyP microparticles, as a component of a newly developed formulation of a dentifrice, turned out to be most effective in inhibiting growth of …
Total mercury and methyl-mercury contents and accumulation in polar microbial mats.
2014
Although polar regions are considered isolated and pristine areas, the organisms that inhabit these zones are exposed to global pollution. Heavy metals, such as mercury, are global pollutants and can reach almost any location on Earth. Mercury may come from natural, volcanic or geological sources, or result from anthropogenic sources, in particular industrial or mining activities. In this study, we have investigated one of the most prominent biological non-marine communities in both polar regions, microbial mats, in terms of their Hg and methyl-mercury (MeHg) concentrations and accumulation capacities. The main hypotheses posed argued on the importance of different factors, and to test them…
Grapefruit essential oils inhibit quorum sensing of Pseudomonas aeruginosa.
2019
Citrus essential oils are used in food to confer flavor and aromas. The citrus essential oils have been granted as GRAS and could be used as antimicrobial additives to control bacterial quorum sensing from potential food bacterial pathogens. The chemical composition and inhibitory activity of Citrus paradisi (grapefruit) essential oils obtained by cold-pressed method (EOP) and cold-pressed method followed by steam distillation, against Pseudomonas aeruginosa were determined . The GC-MS analyses of the oil indicated the amount of the essential oil components was highest with D-limonene in both cases. However, the extraction method modified the chemical composition. EOP had higher amount of …
Biogenesis and roles of Lacticaseibacillus casei BL23 membrane vesicles
2023
Gram-positive bacteria of the species Lacticaseibacillus casei (formerly known as Lactobacillus casei) are fermentative bacilli found in dairy products that are known for their anti-inflammatory properties and beneficial effects against pathogens. Like all living organisms, L. casei produces nanostructures of 20 to 400 nm in diameter bounded by a lipid membrane called membrane vesicles (MVs). MVs have been shown to contain various cellular constituents and exert multiple functions. However, despite the growing interest in Gram-positive MVs over the past 10 years, the mechanisms of biogenesis and the roles played by these vesicles remain poorly characterized. In this context, the objectives …
Nanometric ion pair complexes of tobramycin forming microparticles for the treatment of Pseudomonas aeruginosa infections in cystic fibrosis
2019
Abstract Sustained pulmonary delivery of tobramycin from microparticles composed of drug/polymer nanocomplexes offers several advantages against traditional delivery methods. Namely, in patients with cystic fibrosis, microparticle delivery can protect the tobramycin being delivered from strong mucoadhesive interactions, thus avoiding effects on its diffusion toward the infection site. Polymeric ion-pair complexes were obtained starting from two synthetic polyanions, through impregnation of their solid dissociated forms with tobramycin in aqueous solution. The structure of these polymeric systems was characterized, and their activities were examined against various biofilm-forming Pseudomona…
Pharmaceutical potential of synthetic and natural pyrrolomycins
2015
The emergence of antibiotic resistance is currently considered one of the most important global health problem. The continuous onset of multidrug-resistant Gram-positive and Gram-negative bacterial strains limits the clinical efficacy of most of the marketed antibiotics. Therefore, there is an urgent need for new antibiotics. Pyrrolomycins are a class of biologically active compounds that exhibit a broad spectrum of biological activities, including antibacterial, antifungal, anthelmintic, antiproliferative, insecticidal, and acaricidal activities. In this review we focus on the antibacterial activity and antibiofilm activity of pyrrolomycins against Gram-positive and Gram-negative pathogens…