Papers by Keyword: Escherichia coli

Abstract: This research investigates the utilization of Escherichia coli and Lapindo mud in a two-chamber Microbial Fuel Cells (MFCs) series. MFCs are tools that convert chemical energy into electrical energy with the help of catalytic reactions from microorganisms. This research uses a dual chamber reactor connected by a salt bridge, with graphite electrodes placed in each chamber and connected by copper cables. Lapindo mud contains heavy metals, such as Cu and Pb. In small amounts, heavy metals required for maintaining various biochemical and physiological functions in living organisms, but in greater amounts they can become hazardous or toxic. Heavy metals are major environmental contaminants. The toxicity of heavy metals is an important issue for ecological, evolutionary, nutritional, and environmental reasons. Lapinda mud was placed in the cathode chamber to produce electricity. The cathode chamber was packed using a mixture of Lapindo mud, ammonium chloride, and sulfuric acid. Various amount Lapindo mud was applied, such as 35, 45, and 55 g. On the anode side, E. coli bacteria was used as microorganisms under anaerobic conditions with glucose as a substrate. E. coli undergoes metabolism, producing NAD+ to transfer electrons to produce electricity. Electrical voltage measurements are carried out periodically every hour for 35 h. The best performance was achieved when 55 g of Lapindo mud was used. The exponential phase of E. coli growth occurred at 10 h of cultivation, resulting in a spike in electricity production of 228.13 mV. After reaching the stationary phase of bacterial growth, the electricity generation remained constant for 19-30 h, which reached 342.9 mV; 0.01 mA, 0.034167 watts.

Abstract: The hydrothermal synthesis of amikacin modified carbon dots-doped nitrogen and zinc- (N,Zn-CDs) and its capacity to detect Escherichia coli (E. coli) have been investigated. Amikacin is one of the aminoglycoside antibiotics utilized in this study as a ligand of N,Zn-CDs to attach to E. coli. This study also examined the effect of nitrogen (N) and zinc (Zn) dopant content on enhancing N,Zn-CDs fluorescence emission intensity. N,Zn-CDs were characterized using a spectrofluorometer, UV-Vis spectrophotometer, FTIR, EDX, XRD, and TEM, which revealed their amorphous nature and average particle size of 3 nm. The emergence of bond vibrations of C=O, CN, and ZnO indicates the success of N and Zn dopants. Amikacin was then included in the structure of N,Zn-CDs to enhance their ability to detect E. coli. The maximum fluorescence intensity was seen in N,Zn-CDs with a mole ratio of 1:4:4 mmol for the carbon precursor, N, and Zn dopants, and a volume of 0.1 mL amikacin. Based on the fluorescence response of amikacin-modified N,Zn-CDs against E. coli, a limit of detection 1,490 cfu mL^-1 was obtained.

Abstract: Copper Nanoparticle (CuNP) is mixed as nanofiller to Acrylonitrile Butadiene Styrene (ABS) to produce a material that can control bacterial growth on material surfaces and improve antibacterial performance. The nanocomposite is produced via melt compounding using a twin-screw extruder. Three samples are prepared with 0%, 1.5% and 3% Copper Nanoparticle loading. The samples are extruded, placed in a mold and processed in a compression molding machine. The samples were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Dynamic Mechanical Testing (DMA) and Antibacterial Testing. Results from FTIR shows presence of molecular vibrations of Acrylonitrile, Butadiene and Styrene groups with the presence of foreign substances identified as an additive used in commercial ABS production. XRD showed the incorporation of copper nanoparticles in the nanocomposites. DMA results shows that the incorporation of copper nanoparticles into the ABS matrix results to diverse effect on its mechanical and thermal property. Lastly, antibacterial test showed that both 1.5 wt% CuNP and 3 wt% CuNP exhibited high effectivity on inhibiting Escherichia coli. Index terms: Copper Nanoparticle, Acrylonitrile Butadiene Styrene, filler, nanocomposite, antibacterial material, melt compounding, twin-screw extruder, Escherichia coli.

Abstract: The spontaneous progress in scientific bases to combat infections resulting from pathogenic microbial colonies has led to the development of nanomaterials capped with plant phytochemicals that possess exceptional bacterial growth resistance. In this study, the Authors report an economical biogenic synthesis of zinc oxide nanoparticles and its nanocomposites with silver, gold, and silver-gold bimetal to evaluate their antibacterial potency towards bacterial colonies. Further, these nanomaterials were functionalized with tea-phytochemicals for cost-effective synthesis, as a biogenic capping and reducing agent, for modulating the growth kinetics of nanomaterials, and because of their synergy with the nanomaterials in improving their antibacterial property. The identification of the biosynthesized nanomaterials was performed through various microscopic and spectroscopic techniques. The model microbes chosen to undergo this study were Escherichia coli, a gram-negative bacterium, and Staphylococcus aureus, a gram-positive bacterium. Based on the anti-bacterial essay, certain factors, such as the nature of the bacteria and nanomaterials, the production rates of superoxide radicals, etc. determined the extent of microbial growth inhibition.

Abstract: Silver nanoparticles (Ag⁰) have attracted the most attention due to their broad antimicrobial application and outstanding activity. The silver nanoparticles are usually in colloidal form, then immobilization the colloid onto solid support is still interesting to explore. In this work, a new method for silver colloidal nanoparticle immobilization on silica gel beads (SiG), which was then symbolized as Ag⁰-[chi-SiG] was conducted and characterized successfully. The finding proved that SiG must be coated with three chitosan film layers to give stable support for silver nanoparticles. This coating method caused the chitosan completely covered SiG, and the chitosan film provides coordination bonding for silver ions. The most appropriate solvent for silver ion impregnation on the surface of chi-SiG is methanol compared to other solvents. Tungsten lamp as the photo-irradiation, which is low cost and environmentally friendly has been proven effective for silver ion reduction, as shown by silver metal colloid UV-Vis surface plasmon resonance at 400-700 nm. Ag⁰-[chi-SiG] showed the antibacterial properties of inhibiting the growth Staphylococcus aureus and Escherichia coli; then it provides the potential application for antibacterial filter material. According to the weight comparison between antibacterial standard and Ag content, then Ag0-[chi-SiG] has two and five times higher of exhibiting zone for each bacteria.

Abstract: Surfactants are amphiphilic molecules, which have hydrophilic and hydrophobic groups. Surfactants have an important role in various fields including agriculture, cosmetics, pharmaceuticals, bioremediation, and the petroleum industry especially EOR but because synthetic surfactants are not biodegradable, it is necessary to produce biodegradable surfactants such as rhamnolipid biosurfactants. Rhamnolipid is a glycolipid biosurfactant produced by Pseudomonas aeuruginosa. This species is a pathogen, so it is needed to overcome this problem by cloning the rhamnolipid gene into Escherichia coli for large-scale production. Rhamnolipid biosynthesis includes three main genes, rhlA, rhlB, and rhlC. The rhlAB produces mono-rhamnolipid and rhlABC produces di-rhamnolipid. The construction involved one plasmid pPM RHLABC (di-rhamnolipid) with T7lac promoter. Characterization of surfactants by E24, IFT, and CMC analysis showed that di-rhamnolipid biosurfactant has the best activity (70%, 0.8 mN/m, and 300 mg/L) than chemical surfactant, sodium dodecyl sulfate (46%, 4.7 mN/m, and 2000 mg/L) at pH 7, 25 °C, and 0% salinity. The conclusion from this research shows that the characteristics of di-rhamnolipid are very promising in the utilization of industrial-scale including EOR technology, agriculture, and pharmacy

Abstract: A protein-based electrospun nanofiber from cold water fish gelatin (FG) including bovine lactoferrin (L) as an antimicrobial substance for food packaging applications was developed. Various amounts of L (0, 5, 10, 15, and 20%) were incorporated into FG electrospun nanofibers in order to test antimicrobial activity by disc diffusion method against Pseudomonas fluorescens, Acinetobacter johnsonii, Aeromonas hydrophila, Flavobacterium psychrophilum, Shewanella putrefaciens, and Escherichia coli commonly cause problems in food safety especially in fish products. It was obviously seen that 15% and 20% wt L incorporated FG electrospun nanofibers had significant inhibition zone against all bacterial strains while 5% and 10% L-FG had lower antimicrobial effects. In order to recommend fish gelatin as a food packaging material, mechanical properties should be enhanced to be competitive with synthetic polymers. It was revealed that mechanical strength of gelatin electrospun nanofibers depended on both fiber morphology and bioactive substance content. Neat FG (N-FG ) bead-free electrospun mats had higher fiber diameter (815 ±40 nm) while 15% and 20% L-FG had relatively lower diameter with beaded morphology, i.e., 348 ±32 nm, 229 ± 44 nm respectively. The tensile strength of 20% L-FG mats was significantly lower than the N-FG mats due to beady and thinner morphology. It can be concluded that L-FG electrospun nanofibers with high antimicrobial activity and improvable tensile strength is promising for active packaging applications.Keywords: Electrospinning, Pseudomonas spp., Escherichia coli, Shewanella spp., biodegradable, active packaging

Abstract: Sizes of silver nanoparticles (AgNPs) have been shown to affect the biological activity of AgNPs. Hydrogel beads loaded with AgNPs have been extensively employed for biomedical applications. However, the influence of AgNPs sizes on biological activity of AgNP-loaded hydrogel beads has not much studied. Our objectives were to investigate the effect of AgNP sizes on the antibacterial activity, the cyto- and genotoxicity of AgNPs/alginate hydrogel beads. AgNPs of different sizes (⁓10 nm for S-AgNPs, and ⁓50 nm for L-AgNPs) were incorporated into alginate hydrogel beads during the preparation. The results showed that, S-AgNPs/alginate hydrogel beads (⁓89% inhibition) at AgNP concentration of 10 µg/ml tended to inhibit the growth of E. coli greater than L-AgNPs/alginate hydrogel beads (⁓49% inhibition) at the same dose. Moreover, at this effective antibacterial concentration (10 µg/ml), S-AgNPs/alginate hydrogel beads exhibited weak cytotoxic effect to HaCaT cells whereas L-AgNPs/alginate hydrogel beads showed non-cytotoxicity to this cell line. Furthermore, treatment of HaCaT cells with 10 µg/ml of S-AgNPs/ or L-AgNPs/alginate hydrogel beads did not result in a significant change in %DNA in tail when compared to untreated cells. Therefore, these AgNPs/alginate hydrogel beads, especially with smaller sized AgNPs, can be used as an antibacterial biomaterial with low cytotoxicity and genotoxicity to human cells.

Abstract: The following study is investigating the different GyrB mutations associated with Escherichia coli clinical isolates. The study interrogates part of the ATPase binding site (a.a 132-199) as it covers most of the naturally occurring mutations in GyrB. The following results were obtained: for Arg-136 two isolates had mutations, the first is isolate-1 (Ala-136), and the second is isolate-5 (Cys-136). Gly-164 had no changes for all tested isolates. For Thr-165 only isolate-3 had a change to Ser-165. Accuracy of sequence translation was checked by sequencing both CFT073 and MG1655. The current study presents novel mutations in the GyrB24 subdomain of the gyrase enzyme. These new mutations showed normal enzyme activity (no reduction in ATPase functions) indicating that they might be a result of GyrB interaction with ATP analog molecules rather than antibacterial agents such as coumarins. Furthermore, our findings are supporting the idea that mutations in the GyrB24 would require synchronization with the efflux pumps to maintain antibiotic resistance against coumarins.

Abstract: PMMA/nanoCu antibacterial plastic was prepared by in situ polymerization using MMA as monomer, BPO as initiator and surface treated nanoCu as antibacterial agent. AMEO was used for surface treatment of nanoCu. ATR-FTIR spectra showed that AMEO successfully reacted on the surface of nanoCu. SEM spectra showed that nanoCu dispersed evenly in the PMMA/nanoCu composite. Antibacterial test results showed that the composite had a strong antibacterial effect on Escherichia coli, and the antibacterial rate reached more than 99%. Therefore, the PMMA/nanoCu composite can be used in various fields of antibacterial plastic products.