Papers by Keyword: E. coli

Abstract: The aim of this work was to investigate the influences of different concentrations of Ag₃PO₄ aqueous dispersion by measuring the bacteriostatic characteristic against bacteria E. coli. The Ag₃PO₄ particles were successfully synthesized by precipitation method. Then, the morphological, structural and chemical compositional analyses were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. All these analyses confirmed the formation of Ag₃PO₄ particles with the shape of nearly spherical with a size of 100 – 700 nm. Meanwhile, Kirby-Bauer disk diffusion susceptibility test was chosen to determine the sensitivity of E. coli to antibacterial compounds in Ag₃PO₄ particles. The results showed that the antibacterial ability was significantly improved by increasing the concentration of Ag₃PO₄ aqueous dispersion, and the best concentration was 600 mg /mL. This study suggested that Ag₃PO₄ particles can be exploited as an effective candidate for antibacterial agents.

Abstract: Escherichia coli bacteria sensors have been broadly developed broadly to overcome a diarrheal disease caused by Escherichia coli on poor hygienic water. Sensing layer, as a main part of the sensor, contacts directly to the analyte on sensors system. Some materials were costly and harmful to detect bacteria. Potentially, graphene is a natural carbon derivative with some excellence properties; easy synthesis, and biocompatible. Hence, the quality of the SiO₂/graphene sensing layer was conducted through optical, physical, and electrical characterization to analyze biocompatibility, repeatability, and selectivity. The result showed that Escherichia coli bacterial growth was found around SiO₂/graphene after bacterial exposure indicating a biocompatible material. Raman peak also pointed the fingerprint of graphene after 25 times Escherichia coli exposure through G (1584.52 cm^–1) and 2D peak (2701.5 cm^–1) promising as a repeatable material. The ID/IG ratio increased by the time the bacteria exposure times increased indicating a withstand material from defects and or disorders after bacteria exposure. Through I/V meter, the increasing number of Escherichia coli could increase the resistance value of SiO₂/graphene. This sensing layer could detect the presence of Escherichia coli in limit of detection 16 CFU/mL.

Abstract: Biofouling and biofilms exist as ubiquitous, undesirable accumulation of flora and fauna upon a given substrate when being immersed into an aquatic medium. Therefore, a novel antifouling based materials with the incorporation of nanotechnology has been developed for the prevention of biofouling in its initial stage through photocatalytic treatment. This study investigated the antimicrobial properties of photoactive Cerium (Ce) doped ZnO powder and explores its potential properties for future antifouling application. ZnO nanoparticles was doped with 0.4 mol% Ce was synthesized through the combination of modified citrate gelation technique and solid state sintering. The successful preparation of Ce doped ZnO was confirmed by XRD and SEM. The antimicrobial activity of Ce doped ZnO against E. coli and S. aureus was determined through antibacterial susceptibility test by agar well diffusion method whilst its photocatalytic inactivation efficiency against selected bacteria was analysed through photodegradation testing under UV light irradiation. The findings demonstrated that the synthesized Ce doped ZnO powder exhibited antibacterial effect against Gram-positive bacteria (S. aureus) and excellent photocatalytic efficiency to inactivate both Gram-negative (E. coli) and Gram-positive (S. aureus). 2 g/L of Ce doped ZnO catalyzed the 100% disinfection of both bacteria in 180 min of UV light exposure. Thus, this proved that Ce doped ZnO powder has the potential as efficient antifouling agent.

Abstract: Plant Rumput Mutiara (Hedyotis corymbosa (L.) Lamk) is one of the family species of Rubiaceae which is used as a traditional medicine that is effective in healing boils, acne, anti-inflammatory, and anticancer. Research methods include maceration, fractionation, purification, class test and bioactivity test with Kirby-Bauer diffusion method using E.coli bacteria. The results of this research are pure isolates with white crystal needle shape with melting point 137-138°C. Pure isolates were analyzed using FTIR, and by the IR spectrum which showed the absorption band at wave numbers 3435.22 cm-1 indicated the presence of –OH, CH₃ and-CH₂- aliphatic groups (2956.87 cm-1; 2935.66 cm-1; 2893.22 cm-1; and 2866.22 cm-1), C = C (1641.42 cm^-1), -CH₃ and-CH₂- bending (1462.04 cm^-1 and 1377.17 cm^{- 1}), CO (1056.99 cm^-1), and = CH (964.41 cm^-1). Based on the result, it showed that the isolate was steroid group which has low antibacterial activity againts E.coli with inhibition power of 10 mm.

Abstract: A visible active antibacterial agent, namely TiO₂-Ag-Nanoparticle has been prepared, characterized, and examined to combat E.coli bacteria in the present of the visible light. The preparation was carried out by reduction of AgNO₃ solution over TiO₂ photocatalyst under UV light exposure. TiO₂-Ag nanoparticle was characterized using XRD, SEM and DRS instruments. The activity as an antibacterial agent has been tested for disinfection of E. coli bacteria in the contaminated well water. The antibacterial assay was carried out by visible light irradiation of the contaminated well water in the present of TiO₂-Ag, as well as TiO₂for comparison, for the various period. The antibacterial performance was represented as the number of the bacteria determined by colony counting method. Their XRD patterns probe that the Ag doping leads to the crystalline of TiO₂partially destroyed and the average particle size of TiO₂ in TiO₂-Ag is larger thanTiO₂bare, and no peaks of Ag metal appeared, implying that the Ag silver is very small(nanoparticle) that may be inserted into the TiO₂crystal lattice. Based on the DRS spectra it is observed that TiO₂-Ag has visible light absorption meanwhile TiO₂only can absorb the UV light. The antibacterial assessment demonstrates that the TiO₂-Ag has high performance in the bacterial inactivation under visible light. Meanwhile, very low activity is shown by TiO₂. Moreover, the increase of Ag loaded gives rise in the bacterial inactivation, but further increase leads to the inactivation slightly reduced. The extension time of the visible light exposure is found to promote more effective antibacterial process up to maximum level, and no effect was observed with the much longer time. It is also confirmed that a small amount of Ag is dissolved from TiO₂-Ag NP during the antibacterial testing.

Abstract: This study analyzes the effects of the devices that work at the frequency of 2450 MHz and that release electromagnetic waves on the growth of bacteria. E. Coli bacterial cells are used in this experiment. The bacterial cult is divided into two groups under sterilized conditions. For both groups, the temperature is held constant at 37 Co while the heating effect of the devices working at the frequency of 2450 MHz is minimized. Then, the bacterial cells in the experimental group are exposed to the electromagnetic waves released by the devices working at the frequency of 2450 MHz while the control group is incubated for 8 hours without any exposure to electromagnetic waves. At each hour, samples from the E. Coli bacteria that are exposed to electromagnetic waves and from the control group. After measuring the optical density of the samples, it is found that the electromagnetic waves released by the devices working at the frequency of 2450 MHz have negative effects on the growth of bacteria. So, the effects of the electromagnetic waves released by the devices working at the frequency of 2450 MHz on the growth of the bacteria might be thermal or stress-related. However, there is a need for further physiologic and morphologic studies on this issue. The studies on this issue should be conducted for the public health.

Abstract: Conducting polymers are excellent host materials for nanoparticles of metals and semiconductors. PANI-Ag-Co nanocomposite was prepared by chemical oxidative polymerization of aniline monomer in the presence of nitric acid. PANI-Ag-Co thin films were deposited on the glass substrate using spin-coating technique. The films were characterized by UV-Vis spectroscopy, XRD, AFM and TEM to analyze the internal structure and surface morphology. The performance of the sensor was conducted using I–V measurement to obtain the changes in the current before and after the incubation with E. coli bacteria in water. In UV-visible absorbance bands, a single peak appears at 421.6 nm in each band indicating the Ag-Co alloy nanoparticles were formed. The peaks in the XRD patterns show the crystals are oriented along (111) planes for Ag while (200) plane for Co. AFM images indicate the surface roughness of the PANI-Ag-Co films decreases when the concentration of Co increased. TEM image shows spherical shaped of Ag-Co alloy particles with diameter in the range of 6 – 10 nm. I–V measurements show that the current change of the films increased when incubated in E. coli. The sensitivity on E. coli increases as we increase the Co concentration. PANI-Ag-Co nanocomposite thin films can be explored further for microbial sensor application in future study.

Abstract: The increase of bacterial resistance to synthobiotics makes it relevant to search for new medicinal materials with antibiotic properties. Antimicrobials based on plants represent a huge untapped source of medicines. Antibiotic properties of 34 plant species of Altai flora are studied in this paper. Extracts from plants were obtained by supercritical fluid extraction using supercritical carbon dioxide. Antimicrobial activity of these extracts was determined by micromethod of serial dilutions in liquid media. Escherichia coli XL-1 blue and Staphylococcus aureus 209 strains were used as test-cultures. Upon the results of the study, the extracts from raw material of Penthaphylloides fruticosa and Ribes nigrum can be considered as the most promising for further pharmacological evaluation as new medicinal materials

Abstract: A novel galactoside derivative (1) incorporating p-nitroaniline (p-NA) as chromophore has been synthesized and used as a cascaded chromogenic enzyme substrate for the detection of β-D-galactosidase, which was characterized using UV, ¹H NMR, ¹³C NMR and MS spectra. A plausible mechanism for the release of p-NPA from the enzyme substrate 1 was proposed.

Abstract: Combination of disinfection method gives advantages. In this work, inactivation of E. coli using ZnO nanofluids and ultrasound is evaluated. Growth curves of bacteria were investigated to reveal the inactivation activities of ZnO nanofluids and ultrasound. The effects of combination of ZnO nanofluids and ultrasound, ultrasound time, ultrasound induction point and the induction order of ZnO nanofluids and ultrasound were studied. The results suggested that combination of ZnO nanofluids and ultrasound gives better inactivation effect on E. coli when comparing with single disinfection method. Ultrasound for 10 s helped ZnO nanofluids inhibiting bacteria better than ultrasound for 30 s /60 s. Ultrasound induction point (at 0 hr, 2 hr or 4hr) did not affect on ZnO nanofluids to exhibit the inhibiting property. Induction ultrasound prior to adding ZnO nanofluids showed the better inactivation effect on E. coli. The results also displayed that in this work, ultrasound was mainly worked as a pre-treatment step, instead of a disinfection method.