Synthesis of Ag-Loaded TiO<Subscript>2</Subscript> Electrospun Nanofibers for Photocatalytic Decolorization of Methylene Blue

Titanium dioxide (TiO₂) is one of the excellent photocatalysts used for degradation of environmetal pollutants. In this work, 2.5, 5.0 and 7.5 wt.% of silver (Ag)-loaded TiO₂ nanofibers of mean size 52–134 nm were synthesized by electrospinning method. These electrospun nanofibers were calcined at 500 °C to enable the transformation of Rutile (R) phase to Anatase (A), elimination of reaction moieties from the TiO₂ matrix and subsequently formation of Ag clusters. The effect of Ag loading on the morphology, crystal structure, phase transformation, and band gap of these electrospun nanofibers have been characterized by scannining electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), raman spectroscopy and UV-visible spectroscopy. These nanofibers exhibited a red-shift in the absorbance edge and a significant enhancement of light absorption in the wavelength range of 250–550 nm. These electrospun nanofibers were investigated for photodecomposition of methylene blue (MB), and photocatalytic decolorization rates were determined by pseudo-first-order equation. The rate constants for the pure and those of 2.5, 5.0, and 7.5 wt% Agloaded TiO₂ nanofibers were computed to be 0.1439 min^-1, 0.1608 min^-1, 0.1876 min^-1, and 0.2251 min^-1 respectively.     

Virulence-associated genes and antimicrobial resistance among avian pathogenic Escherichia coli from colibacillosis affected broilers in Pakistan

Avian pathogenic Escherichia coli (APEC) causes colibacillosis that leads to high morbidity and mortality among poultry birds. To date, there is a lack of knowledge about virulence-associated genes (VAGs) and multidrug resistance of APEC isolates from Pakistan. In this study, we determined the VAGs and antibiotic resistance profiles of APEC isolates recovered from colibacillosis affected broilers in Faisalabad region of Pakistan. A total of 84 diseased and dead birds from different local broilers farms were collected and examined for the gross lesions of colibacillosis by conducting postmortem examination. Of these, APEC isolates were recovered from 75 (89.2%) birds. Antibiotic susceptibility tests against 11 antimicrobial agents showed the highest resistance against ampicillin (98.6%) followed by tetracycline (97.3%) and ciprofloxacin (72%). The presence of 11 virulence-associated genes (VAGs) was detected by multiplex polymerase chain reaction (PCR). Of the 75 APEC, 32 (42.6%) harbored > 5 VAGs. Most commonly found genes were increased serum survival (iss; 84%), iron transport (iutA; 74.6%), and colicin V (ColV; 60%). Twenty-two isolates (29.3%) were found to possess a combination of VAGs; iss, tsh, iroN, and iutA, in addition to other VAGs. To the best of our knowledge, this is the first report on the detection of virulence-associated genes and multidrug resistance among APEC isolates in Pakistan. In the future, the strains with the predominant set of VAGs can be used for colibacillosis diagnosis and as a potential vaccine candidate.