The present study investigates the synthesis and characterization of iron oxide nanoparticles (Fe3 O4 -NPs) for their antibacterial potential against Bacillus cereus and Klebsiella pneumonia by modified disc diffusion and broth agar dilution methods. DLS and XRD results revealed the average size of synthesized Fe3 O4 -NPs as 24 nm while XPS measurement exhibited the spin-orbit peak of Fe 2p3/2 binding energy at 511 eV. Fe3 O4 -NPs inhibited the growth of K. pneumoniae and B. cereus in both liquid and soild agar media, and displayed 26 mm and 22 mm zone of inhibitions, respectively. MIC of Fe3 O4 -NPs was found to be 5 μg/mL against these strains. However, MBC for these strains was observed at 40 μg/mL concentration of Fe3 O4 -NPs for exhibiting 40–50% loss in viable bacterial cells and 80 μg/mL concentration of Fe3 O4 -NPs acted as bactericidal for causing 90–99% loss in viability. Hence, these nanoparticles can be explored for their additional antimicrobial and biomedical applications.
Herein, an effort was made to investigate the antibacterial potential of agarose nanoparticles (ANPs) and poly(quaternary ammonium) modifi ed ANPs (mANPs) against Escherichia coli (gram-negative bacterium) and Staphylococcus aureus (gram positive bacterium) in liquid systems as well as on agar plates. ANPs were synthesized by nanoprecipitation technology and characterized by XRD, TEM, TGA, DTA and DLS. The particle size estimated was 30 nm while atomic force microscopy was used to observe the interaction of ligand on ANPs. Antimicrobial characterization was monitored by colony forming units (CFU) as a function of ANPs concentration on agar plates. It was observed that ANPs showed 15 x 109/ml CFU after 24 hours of incubation at 20 mM ANPs concentration while the modified ANPs exhibited 21 x 109/ml CFU under similar incubation conditions. Moreover, zone of inhibition (ZOI) was 2.9 and 3.8 cm, respectively for E. coli by ANPs at 0.2 and 0.4 mM, respectively while it was 3.2 and 3.8 cm respectively by modified ANPs under similar conditions. Similarly, ZOI for S. aureus by ANPs at 0.2 and 0.4 mM was observed at 3.1 and 4.0 cm, respectively, while these values were 3.5 and 4.1 cm, respectively for modified ANPs under similar incubation conditions.
The present study demonstrates the immobilization of β galactosidase from apricots (Prunus armeniaca kaisa) on an inexpensive concanavalin A layered cellulose-alginate hybrid gel. Immobilized β galactosidase retained 78% of the initial activity after crosslinking by glutaraldehyde. It exhibited greater fraction of activity at both acidic and basic pH, and showed broad spectrum temperature optimum as compared to free enzyme. Moreover, immobilized enzyme exhibited higher thermal stability at 60oC and retained 80% of the original enzyme activity in presence of 3% galactose. The crosslinked immobilized enzyme showed improved hydrolysis of lactose from milk and whey in batch processes at 50oC as well as in continuous reactors operated at flow rate of 20 mL/h and 30 mL/h even after one month. Moreover, crosslinked adsorbed β galactosidase retained 76% activity even after its sixth repeated use, thereby promoting its use for lactose hydrolysis in various dairy products even for longer durations.
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