Anti-Salmonella type H-z4 Polyclonal antibody

Gold nanoparticles capped with chitosan (CH-NGs), glycol chitosan (GC-NGs) and poly(gamma-glutamic acid) (PANGs) were synthesized separately, characterized and evaluated for catalytic and antibacterial activities. Surface Plasmon resonance peak at 520-530 nm confirmed the formation of NGs, while FTIR spectra revealed the involvement of hydroxyl, amine and amide groups in biopolymers on NGs formation and coating. Particle size, zeta potential and surface coating were respectively 21.7 nm, +50.2 mV and 20% for CH-NGs, 5.6 nm, +46.5 mV and 43.5% for GC-NGs and 7.4 nm, -37.3 mV and 34.5% for PA-NGs. Compared to citrate-capped NGs (CT-NGs), biopolymer-capped NGs exhibited high catalytic activity in a 4-nitrophenol reduction model with the pseudo first-order catalytic rate for PA-NGs being 4-6 fold higher than CH-NGs and GC-NGs. No significant antibacterial effect was shown for CT-NGs. However, PA-NGs was superior to gentamycin in inhibiting Salmonella enterica and Escherichia coli-O157:H7, while CH-NGs and GC-NGs showed the highest antibacterial effect against Listeria monocytogenes, followed by Salmonella enterica, Escherichia coli-O157:H7, methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus. TEM images showed that GC-NGs were attached on MRSA surface to alter cell permeability, block nutrient flow and disrupt cell membrane, whereas PA-NGs penetrated into Salmonella enterica to generate cavities, plasmolysis and disintegration. (c) 2020 Elsevier B.V. All rights reserved.

It is difficult to detect a small amount of pathogens present in ready-to-eat foods without enriching it. Although enrichment is needed to increase the bacterial population, the time required for this impedes the rapid detection of pathogens. This study was designed to detect Escherichia coli O157:H7 and Salmonella Typhimurium more quickly and sensitively by concentrating bacteria and DNA. Short-term enrichment was used to increase bacterial number and to recovery injured bacteria. Filtration was used to concentrate pathogens and to lower the detection limit. DNA concentration was performed to improve sensitivity by reducing elution volume. Samples were analyzed using real-time PCR. The results showed filtration after enrichment for 2 h allowed the effective detection of E. coli O157:H7 and S. Typhimurium. S. Typhimurium was detected following enrichment for 1 h when DNA concentration was performed. After validation, enrichment for 3 h was shown to be required for detecting E. coli O157:H7 and S. Typhimurium. With DNA concentration, enrichment for 3 h was necessary for the complete detection of E. coli O157:H7, but that for 2 h was needed for S. Typhimurium. The results of this study indicate that this combined method is a rapid and efficient way of detecting pathogens.