Papers by Keyword: Biofilm

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Authors: Sroisiri Thaweboon, Boonyanit Thaweboon, Rattiporn Kaypetch
Abstract: Vanillin is a major constituent of vanilla seeds which is used as a flavoring agent in both food and non-food industries. Previous reports have showed that vanillin had antimicrobial properties against food spoilage bacteria, yeasts, and molds. However, investigations about its effect on oral pathogenic yeasts are scarcely found. Objective: This study aims to determine the effect of vanillin on candida biofilm formation in vitro. Method: Vanillin (Sigma-Aldrich, UK) was prepared in 99.7% ethyl alcohol and diluted to concentrations of 0.5-20 mM. Biofilms of Candida albicans (ATCC 10231 and 2 clinical strains) were grown on the bottom of 96-well plate with Yeast Nitrogen Base (YNB) medium supplemented with 100 mM glucose in a shaking incubator at 37oC for 24 h. After washing, each concentration of vanillin was added with YNB supplemented with 200 mM glucose. The plate was incubated in shaking incubator for another 24 h at 37oC. Evaluation of biofilm was assessed through the XTT reduction assay. A solution of 0.2% chlorhexidine gluconate solution and 99.7% ethyl alcohol were used as positive and negative controls respectively. Result: It was found that 75-80% candida biofilm reduction was demonstrated at concentrations of 10.5-20 mM vanillin whereas chlorhexidine exhibited 94% biofilm reduction. Conclusion: Our results indicate that vanillin is a promising agent that can be used to cure candida infection in the oral cavity. Further studies are required to evaluate its effect on other yeast strains and cytotoxicity before consideration for usage in patients.
Authors: Cheng Cheng Qiang, Baoan Li, Jian Zhang
Abstract: A membrane-aerated bioreactor (MABR) was developed for the wastewater treatment with simulated oilfield wastewater. Long-running experimental results showed that the removal percentages of oil and COD were 80-90% and 75-85% respectively and the concentration of NH4+-N was less than 2 mg/L, turbidity less than 50 NTU in the effluent. The results lay a good foundation for further research and development of MABR treatment process and technology. MABR has the technical feasibility for the oilfield wastewater treatment.
Authors: Yan Zhang, Li Li Wang, Zheng Yang Yang, Xu Ying Zhao, Huan Guang Liu, Min Zhu
Abstract: In this study, the effect of environment materials for civil engineering was investigated through two sets of parallel reactors with sodium acetate and starch as carbon source separately. The reactors were started up by two stages, including biofilm formation stage and biofilm domestication stage. In biofilm domestication stage, the average removal efficiencies of COD were 88.84% and 88.78% respectively. NH4+-N removal efficiencies were reached at 99.28% and 91.90%. Total nitrogen(TN)removal efficiencies were 45.25% and 45.45%. By PCR-DGGE, it was found that there were high similarities between biofilm and suspension in the reactors. Different types of carbon sources enriched different types of microorganisms. The study can provide references for studying simultaneous nitrification and denitrification(SND)and optimizing carbon sources.
Authors: Ana P. Felício, Eliandre de Oliveira, M.A. Odena, Oswaldo Garcia Jr., Maria C. Bertolini, Lúcio F.C. Ferraz, Laura M.M. Ottoboni, Maria T.M. Novo
Abstract: The Acidithiobacillus ferrooxidans periplasmic space is known to have proteins involved in the respiratory chains. There are no reports about the expression of the periplasmic proteins in A. ferrooxidans cells attached to chalcopyrite. In this preliminary work, it was compared the periplasmic protein profiles of A. ferrooxidans planktonic and attached cells after exposure to chalcopyrite for 2 hours. The bacterial response to chalcopyrite was investigated by a proteomic approach (two- dimensional gel electrophoresis and mass spectrometry). Four proteins differentially expressed between planktonic and attached cells after exposure to chalcopyrite were identified. Two of these proteins, repressed in chalcopyrite- attached cells, were both identified as superoxide dismutase, whereas the single strand binding protein (SSB) and the PspA/IM30 protein were induced. These results showed that A. ferrooxidans chalcopyrite- attached and planktonic cells show differential expression of the periplasmic proteins and that a proteomic approach can provide a valuable tool to detect proteins related to the A. ferrooxidans response to attachment to the mineral substrates.
Authors: P. Yong, M. Paterson-Beedle, W. Liu, Z. Zhang, D.A. Beauregard, M.L. Johns, Lynne E. Macaskie
Abstract: This study describes biofilm formation as a non line-of-sight coating method on support materials such as polyurethane foam, porous glass, polypropylene (PP) and titanium alloy, using a Serratia sp., which can manufacture extracellular nanoscale scaffolded hydroxyapatite (HA) crystals via enzymatic cleavage of glycerol 2-phosphate (G2P) in the presence of CaCl2. Various microscopies and non-invasive magnetic resonance imaging were used to visualize the biofilm coating on the support surface. A novel micromanipulation technique was used to estimate the adhesive strength of native and HA-mineralized biofilms. The biofilm with HA was up to forty times stronger than that without HA. A coating of nano-HA (> 80 m) onto a biofilm-Ti disc was achieved.
Authors: Wimol Phoudee, Wanida Wattanakaroon
Abstract: Application of dressing material is generally aimed to maintain a moist environment at the wound interface, allow gaseous exchange, prevent the wound directly contact to microorganisms and remove excess exudates. The wound dressing synthesized from biocompatible materials are of interest due to the desired properties such as non-toxic, non-allergenic, non-adherent, and easily removed without trauma. The objective of this research is to synthesize a multifunctional peptide dressing which could provide an antimicrobial activity against Pseudomonas aeruginosa planktonic bacteria and biofilms and help tissue regeneration. Sample suspensions of the 6% (w/v) BSA and 8% (w/v) peptide extract heated for 30 minutes were used for hydrogel dressing preparation. For gel pad casting, 8% (w/v) BSA also heated to 100 °C for 20 minutes followed by rapid cooling in cold water. To crosslink their structure, 0.25% (w/v) NaCl solution was added. The suspensions were later cooled down at 4 °C for 2 hours. Both hydrogel dressings contained either 10 μg/ml of ciprofloxacin or 10 μg/ml of tobramycin and 10 μM of astaxanthin. The antimicrobial test indicated that the BSA hydrogel had the activity against planktonic cells with the log reduction value of 6.19 ± 0.12 for ciprofloxacin and 6.50 ± 0.51 for tobramycin. The peptide hydrogel containing ciprofloxacin and tobramycin resulted in 7.68 ± 0.33 and 6.13 ± 0.40 log reduction, respectively. Both antibiotic drugs exhibited lower effect on the viability of P. aeruginosa in colony biofilms. The qualitative results observed with the wound pads also revealed higher viability of established biofilms, suggesting the antibiotic tolerance of these biofilms. This finding aids in the development of novel biomaterial wound dressing.
Authors: Fong Lee Ng, Siew Moi Phang, Vengadesh Periasamy, Kamran Yunus, Adrian C. Fisher
Abstract: Algae are amongst the most photosynthetically efficient organisms harnessing solar energy for all its metabolic life-supporting activities. The solar energy is transformed into chemical energy in a normally wasteful process. In this study, this excess wasted energy may be directed towards electricity generation in a biophotovoltaic platform. This is a new approach in renewable energy production from algae. As an initial step, algal biofilms are established on indium tin oxide (ITO) anodes. Two microalgae, the unicellular Chlorella UMACC 313 and the filamentous Spirulina UMACC 159 were used to form biofilm on ITO anodes under three different treatments (T1: unmodified smooth surface , T2: modified surface etched with interval of 2.5 mm between lines and T3: modified surface etched with interval of 1 mm between lines). Results show significantly higher biofilm coverage on the etched anodes compared to the smooth ones. Anodes of T3 registered the highest biofilm coverage of 99.46% for Chlorella. For Spirulina, highest biofilm coverage (80.70%) was observed on T2 anodes. The increase in biofilm coverage successfully resulted in increase of photosynthetic efficiency for both strains. Spirulina registered the highest maximum relative electron transport rate at 153.507 μmol electrons m-2s-1 compared to Chlorella (140.796 μmol electrons m-2s-1). This was correlated to pigment content. Biofilms established on the ITO anodes and the resulting high rate of photosynthetic efficiency achieved in these experiments are expected to enable electrical energy production from biophotovoltaic platforms.
Authors: Robert J. Huddy, Rose Kantor, Wynand van Zyl, Robert P. van Hille, Jillian F. Banfield, Susan T.L. Harrison
Abstract: Gold extraction by cyanidation from refractory gold ores results in the formation of thiocyanate-and cyanide-contaminated wastewater effluents that must be treated before recycle or discard. Activated sludge processes, such as ASTERTM, can be used for biodegradation of these effluent streams. The destruction of these compounds is catalyzed by a mixed microbial culture, however, very little is known about the community composition and metabolic potential of the thiocyanate-and cyanide-degrading microorganisms within the community. Here we describe our on-going attempts to better understand the key microorganisms, within the ASTERTM bioprocess, that contribute to the destruction of thiocyanate and cyanide, and how this knowledge relates to further process optimisation.
Authors: Ana Lucia do Amaral Escada, Cristiane Aparecida Pereira, Antonio Olavo Cardoso Jorge, Ana Paula Rosifini Alves Claro
Abstract: In the present work, the efficacy of the Ti–7.5Mo alloy nanotube and Ti–7.5Mo alloy nanotube with chlorhexidine against bacterial biofilm formation was evaluated. Nanotubes were processed using anodization in 0.25% NH4F electrolyte solution. Biofilms were cultured in discs immersed in sterile brain heart infusion broth (BHI) containing 5% sucrose, inoculated with microbial suspension (106 cells/ml) and incubated for 5 days. Next, the discs were placed in tubes with sterile physiological solution 0.9% sodium chloride (NaCl) and sonicated to disperse the biofilms. Tenfold serial dilutions were carried and aliquots seeded in selective agar, which were then incubated for 48 h. Then, the numbers CFU/ml (log 10) were counted and analyzed statistically. Scanning electron microscopy (SEM) on discs with biofilms groups and contact angle was carried out. The results show that there is no difference in bacterial adhesion between of the Ti–7.5Mo alloy nanotube and Ti–7.5Mo alloy nanotube with chlorhexidine.
Authors: Duongruitai Nicomrat, Jirasak Tharajak
Abstract: Present study consisted a possible novel natural antimicrobial agent replacing chemicals for preventing the microbial growth and microbial biofilm accumulated on silicone. Since squid ink has long proved to play various primary roles in wide ranges of alternative therapeutic medicine and food applications. This research was designed to report the potential antimicrobial effects of squid ink especially after heat treatment against the microorganisms causing biofilms. Various temperature conditions comprising room temperature (RT), 40, 60, 80, and 100°C were applied to the crude squid ink. Two fresh ink samples isolated from splendid squid (Loligo duvauceli) and soft cuttlefish (Sepioteuthis lessoniana) were determined for their antimicrobial activities after heat treatment on most reported microbes causing biofilms on these plastic substrates. The results showed that after pretreatment at RT-50°C for 15 min, fresh crude ink of L. duvauceli consistently presented higher bioactive activity (> 15 mm diameter) than S. lessoniana(5-10 mm diameter), based on a zone of inhibition of disc diffusion method. From this study, both squid inks could definitely be future applied as active antimicrobial ingredients into silicone.
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