Silver nanoparticles form promising template for designing antimicrobial agents against drug resistant pathogenic microorganisms. Thus, the development of a reliable green approach for the synthesis of nanoparticles is an important aspect of current nanotechnology research. In the present investigation, silver nanoparticles synthesized by a soil Bacillus sp. were characterized using UV-vis spectroscopy, FTIR, SEM, and EDS. The antibacterial potential of biosynthesized silver nanoparticles, standard antibiotics, and their conjugates were evaluated against multidrug-resistant biofilm-forming coagulase-negative S. epidermidis strains, S. aureus, Salmonella Typhi, Salmonella Paratyphi, and V. cholerae. Interestingly, silver nanoparticles (AgNPs) showed remarkable antibacterial activity against all the test strains with the highest activity against S. epidermidis strains 145 and 152. In addition, the highest synergistic effect of AgNPs was observed with chloramphenicol against Salmonella typhi. The results of the study clearly indicate the promising biomedical applications of biosynthesized AgNPs.

No abstract

In the current study, various endophytic bacterial isolates from Piper nigrum were explored for its nanoparticle synthesizing property. Very interestingly, one of the isolate which is a strain of Bordetella sp. was found to have the ability to form silver nanoparticles at room temperature within 24 h by extracellular method. This was confirmed by the presence of a peak at 460 nm in the UV-Vis spectrum and such a result is the indication of surface plasmon resonance of silver nanoparticles. Further characterization of nanoparticles was carried out by Scanning electron microscopy (SEM)analysis. This confirmed the presence of silver nanoparticles with size less than 100 nm. The antibacterial potential of silver nanoparticles synthesized was also tested against pathogens like Salmonella paratyphi, Vibrio cholerae and Staphylococcus aureus. So the current study is the demonstration of an efficient synthesis of silver nanoparticles by Bordetella sp. and their potential as nanomedicine to manage pathogenic bacteria.Keywords: Antibacterial activity, Biosynthesis, Endophytic, Extracellular, Silver nanoparticles, Citation: R. Thomas, et al. Extracellular synthesis of sliver nanoparticles by endophytic Bordetella sp. isolated from Piper nigrum and its antibacterial activity analysis .

The zoonotic spread of antimicrobial resistance (AMR) and the associated infections are becoming a major threat to the human population worldwide. Strategies to identify the potential pathogen dissemination by seemingly healthy livestock are at a nascent stage and it is of significant importance to monitor environmental evolution of AMR. In this study, a multidrug resistant strain of Enterobacter hormaechei MS2 isolated from the feces of healthy broiler chicken has been characterized by whole genome sequencing based method. Here, the isolate was primarily subjected to antimicrobial susceptibility testing followed genome sequencing and analysis. From the antimicrobial susceptibility testing result, the strain was found to be resistant to multiple classes of drugs including the colistin which is an important candidate drug used to treat infectious diseases. The resistome prediction of genomic data further revealed the presence of 7 perfect and 26 strict hits including those for MCR-9 and FosA6. The pathogenicity prediction has also demonstrated the strain to have the potential to be a human pathogen with 0.72 probability. The phylogenetic analysis has also supported the zoonotic potential of the strain due to its clustering with isolates from both human and livestock-associated host groups. The results of the study suggest the need for a strong surveillance system to identify the opportunistic zoonotic pathogens to prevent a silent AMR menace mediated by them. Carriage of multi-drug resistant strains in the livestock gut microbiome is also a serious concern as it has high AMR transmissibility through contact and supply chain activities.

In the current study, various endophytic bacterial isolates from Piper nigrum were explored for its nanoparticle synthesizing property. Very interestingly, one of the isolate which is a strain of Bordetella sp. was found to have the ability to form silver nanoparticles at room temperature within 24 h by extracellular method. This was confirmed by the presence of a peak at 460 nm in the UV-Vis spectrum and such a result is the indication of surface plasmon resonance of silver nanoparticles. Further characterization of nanoparticles was carried out by Scanning electron microscopy (SEM) analysis. This confirmed the presence of silver nanoparticles with size less than 100 nm. The antibacterial potential of silver nanoparticles synthesized was also tested against pathogens like Salmonella paratyphi, Vibrio cholerae and Staphylococcus aureus. So the current study is the demonstration of an efficient synthesis of silver nanoparticles by Bordetella sp. and their potential as nanomedicine to manage pathogenic bacteria.