Papers by Keyword: Biofilm Formation

Abstract: Coronavirus disease 2019 (COVID-19) plays a vital role in the pollution of micro-plastic. Currently, the increase in the use of polypropylene-based face masks has been an issue in waste management. This scenario will someday cause big environmental problems if the wastes are improperly managed. Thus, this review is aimed at analyzing the waste contributed by face masks and studying the factors that help fasten the degradation of face masks. These findings were analyzed according to the degradation of the polypropylene-based face mask under a few headings. The results have been presented and fallen into respective categories, and it shows that polypropylene does undergo deterioration in the landfill burial under the dumping site soil. It has been confirmed that there was heavy colonization of microbial communities from the used face masks. Thus, it is recommended that more research need to be done further to test the microbial effects of polypropylene-based face masks.

Abstract: Bacteria form biofilms to facilitate colonization, and biofilm formation on polymeric medical devices is a common cause of hospital-acquired infection. Simulated body fluid (SBF) is a supersaturated calcium-phosphate solution with ionic composition nearly equal to that of human blood plasma, and has been used to test the bioactivity of materials. The purpose of this work was to understand whether SBF influenced surface structure on bacterial adhesion and biofilm formation on polycarbonate, a polymer commonly used in medical devices. In this study, polycarbonate coupons were immersed in a SBF solution at 37 oC for 7 and 14 days and air-dried for 30 minutes, and compared with deionized water immersion. Colony biofilms of P. aeruginosa were then investigated by growing bacteria on top surface of immersed coupons for 24 and 48 hours, and observed by the quantitative assay (areal cell density) and visualized using a field emission scanning electron microscopy (FESEM). Results stated that a prolonged immersion time of coupons in deionized water enhanced biofilm growth. Immersion in SBF for a period of 14 days showed a significant reduction in the viability following 24 hours of incubation compared to that in deionized water incubated for 48 hours. FESEM further demonstrated that P. aeruginosa had a tendency to form biofilm on a polycarbonate substrate, and was able to develop biofilms on both the SBF and deionized water. Significant cell clusters and bacterial adhesion was observed at 48-hour incubation. These insights can potentially assist in the establishment of infection and colonization of this opportunistic pathogen, and will aid the development of strategies to prevent biofilm formation.

Abstract: Biosynthesis of novel metal nanoparticles (especially silver) using plant derivatives has received increasing attention due to their eco-friendly and potential applications in pharmaceutical and medical fields. In this study, silver nanoparticles were synthesized by using aqueous extract of Lamium album as a biocompatible and green method. The synthesized silver nanoparticles were characterized by Ultraviolet-visible (UV–vis) Spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Dynamic Light Scattering (DLS) Analysis. Inhibitory activity of silver nanoparticles on fungal growth was evaluated and inhibition of Candida albicans biofilms formation was measured using XTT assay. Their antioxidant and cytotoxic properties have also been evaluated.The synthesized AgNPs were mostly spherical in shape with an average size of nearly 25.2 nm. The AgNPs were crystalline in nature and have a face-centered cubic structure. The results of zeta potential value for AgNPs were −30 mV indicating the normal stability of the synthesized nanoparticles in colloidal systems. The result of antifungal activities showed that the biosynthesized silver nanoparticles had inhibitory activity against Candida albicans, C. tropicalis, C. krusei, C. glabrata, C. dubliniensis, C. parapsilosis, Cryptococcus neoformance, Aspergillus flavus, A. clavatus, Aspergillus fumigatus, Pseudallescheria boydii and Exophiala dermatitidis. The nanoparticles inhibited the Candida albicans biofilm formation in a dose-dependent manner. The cytotoxicity study of silver nanoparticles was revealed IC50 of 110.75 μg/mL against liver cell lines. The recognized bioactivity confirmed by the synthesized silver nanoparticles directs towards the potential for using as an antioxidant, antifungal, and cytotoxic agent.Keywords: Green synthesis, Antifungal activities, Silver nanoparticles, Lamium album, Biofilm formation.

Abstract: Reactive oxygen species (ROS), such as hydrogen peroxide (H₂O₂), superoxide (O₂^-) and hydroxyl radicals (OH^.) are known to be formed on the surface of metal sulfides in aqueous solution under oxic and anoxic conditions. Consequently bacteria which have not been adapted to their presence are metabolically inhibited [1], presumably due to the presence of these ROS. Pyrite-grown cells of Acidithiobacillus ferrooxidans^T, in contrast to iron (II)-grown cells, were able to oxidize iron (II)-ions or pyrite after 24 h starvation and contact with 1 mM externally added H₂O₂. In this study, similar results were obtained with Acidiferrobacter sp. SPIII/3. However, Acidithiobacillus ferrivorans SS3 showed the highest tolerance towards contact with H₂O₂, while Leptospirillum ferrooxidans DSM 2391 was most sensitive. Similar results were obtained after exposure to defined doses of gamma radiation, which cleaves water molecules and generates ROS. In this study members of the three aforementioned genera of mineral-oxidizing bacteria were compared regarding their ability to survive, colonize pyrite and to oxidize iron (II)-ions after exposure to different concentrations of H₂O₂. Pyrite colonization was studied after exposure to endogenous ROS formed on pyrite or after external addition of H₂O₂ using confocal laser scanning microscopy (CLSM).

Abstract: In this study, initial attachment to and biofilm formation of Sulfobacillus thermosulfidooxidans DSM 9293^T on pyrite in the presence of Leptospirillum ferriphilum DSM 14647^T were investigated. Interactions of S. thermosulfidooxidans^T and L. ferriphilum^T were studied by means of monitoring attachment behavior and biofilm formation on pyrite. Our preliminary results showed that 1): Pre-established biofilms of L. ferriphilum^T had effects on attachment of S. thermosulfidooxidans^T to pyrite; 2): physical contact between cells of L. ferriphilum^T and S. thermosulfidooxidans^T on pyrite were visible 3): Pyrite leaching by cells of S. thermosulfidooxidans^T was inhibited by the presence of inactive cells of L. ferriphilum^T.

Abstract: A new powder metallurgical processing route for porous Ti coatings on Ti-6Al-4V substrates based on the electrophoretic deposition (EPD) of TiH₂ suspensions is presented. After dehydrogenation and sintering in vacuum, coatings with a fully interconnected porosity (up to 51%, interconnective pore channels (IPC) of 2-50 µm) and high adhesion strength (up to 47 MPa) are obtained. Further evaluation of these coatings for potential use in biomedical implants shows that EPD Ti coatings are significantly less prone to bacterial adhesion compared to state-of-the-art vacuum plasma sprayed (VPS) coatings, while still allowing substantial bone ingrowth. Using EPD, the coating process can easily be transferred to complex-shaped implant components.

Abstract: A functional luxIR-type Quorum Sensing (QS) system is present in Acidithiobacillus ferrooxidans. However, cell-cell communication among various acidophilic chemolithoautotrophs growing on pyrite has not been studied in detail. These aspects are the scope of this study with emphasis on the effects exerted by the N-acyl-homoserine lactone (AHL) type signaling molecules which are produced by Acidithiobacillus ferrooxidans. Their effects on attachment and leaching efficiency by other leaching bacteria, such as Acidithiobacillus ferrivorans, Acidiferrobacter spp. SPIII/3 and Leptospirillum ferrooxidans in pure and mixed cultures growing on pyrite is shown.

Abstract: Biofilm development of F. acidiphilum BRGM4 on polycarbonate filters floating on liquid medium and pyrite surfaces were studied by confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) combined with epifluorescence microscopy (EFM). Results show that F. acidiphilum biofilms were heterogeneously distributed, and varied among different growth conditions, such as inorganic phosphate (P_i) starvation and glucose supplementation. Biofilm and planktonic cells showed significant morphological differences. Capsular EPS were observed in both biofilm and planktonic cells. Cells showed preferential attachment to the cracks/defects of pyrite surfaces.

Abstract: This research has discussed the biofilm formation on the treatment of pharmaceutical wastewater in BAF. The removal rate of COD and NH3-N and law of the performance on the temperature and height of fillers are studied here. The results show that the BAF can still maintain a higher COD removal rate in the 13°C-25°C, the average removal rate reaches 86.9%. The denitrification is impacted by low temperature that the average removal rate of 74.7%. Experiment shows that, from 0cm to 65cm part, the removal rate of COD reachs 86.3%. The good performance of NH3-N removal rate mainly concentrates in the height of 35cm ~ 95cm.

Abstract: In this study, the alternating 3-stage biological aerated filter system with the brush as the filler was proposed for campus sewage treatment and the biofilm formation process was researched. Adopting the four-stage inoculated biofilm formation method, the treatment effects of the 3 filter columns respectively lasted 23d, 20d, 23d to reach stable. After the attached biofilm grew steadily, the effluent COD concentration was between 45 mg/L and 95 mg/L, and the removal efficiency was 77%~85%. The effluent NH₄⁺-N concentration of 1st and 3rd filter columns was 11~25 mg/L, and the removal efficiency was 47%~67%; while the effluent NH₄⁺-N concentration of 2nd filter column was 8 ~19 mg/L, the removal efficiency was 64%~ 78%.