Recombinant Salmonella typhi flagellin [His]

Purified plant nutraceuticals afzelin and quercetrin from an edible plant- Crotolaria tetragona was employed for the fabrication of silver nanoparticles (AgNPs) by a sunlight mediated process. From among a panel of strains tested, AgNPs displayed potent bacteriostatic and bactericidal effect against P. aeruginosa and S. Typhi. Time kill studies revealed green synthesized AgNPs displayed comparable bactericidal effect with chemically synthesized AgNPs against S. Typhi. Antibiofilm potential of AgNPs showed that they were highly effective at sub MIC concentrations in causing 50% biofilm inhibition against food borne pathogen S. Typhi implying that antibiofilm effect is independent of antibacterial effect, which was evidenced by fluorescent imaging and SEM imaging. Mechanistic studies revealed that reduced cell surface hydrophobicity, decreased surface adherence, loss of membrane potential contributed to antibiofilm potential of afzelin/quercetrin AgNPs. Green synthesized afzelin/quercetrin AgNPs were also relatively less toxic and more effective in curtailing bioburden of S. Typhi in infected zebrafish by > 3 log fold. Ability of sunlight reduced afzelin/quercetrin NPs to mitigate planktonic mode of growth in vitro and in vivo and curtail biofilm formation of S. Typhi in vitro demonstrates its potential to curtail food borne pathogen in planktonic and biofilm mode of growth.

We synthesized polysulfone/polyimide nanocomposite membranes by solution casting method and reinforced with silica nanoparticles by in situ and ex situ techniques. Physical characteristics of nanocomposite membranes were explored by using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The appropriate ratio of polysulfone and polyimide was revealed through structural analysis. Thermal analysis revealed highest degradation temperature of 580 degrees C for silica reinforced nanocomposite membrane as compared to that of neat polysulfone membrane which was found to be 500 degrees C. On the other hand, glass transition temperature was found to be 85 degrees C for neat polysulfone membrane which was improved to 205 degrees C for polysulfone/polyimide blend membrane with an indication of better compatibility of glassy polymers. Young's modulus of neat polysulfone membrane was 3565.368 MPa which was increased to 5689.035 MPa for polysulfone/polyimide blend membrane and further increased to 7590.340 MPa for silica reinforced polysulfone/polyimide blend membrane. Membrane properties such as porosity and solvent content values were also explored. The antibacterial properties of fabricated nanocomposite membranes were investigated against Klebsiella pneumonia and Salmonella typhi. Better killing results were obtained against bacteria for PSf/PI/SiO2 nanocomposite membrane. POLYM. COMPOS., 40:1897-1910, 2019. (c) 2018 Society of Plastics Engineers