Abstract
The development of microbial resistance requires a novel approach to control microbial infection. This study implies the microbial synthesis of nanometals and assessment of their antivirulent activity against Pseudomonas aeruginosa. Streptomyces isolate S91 was isolated from soil with substantial ability for growth at high salts concentrations. The cell-free supernatant of S91was utilized for the synthesis of Au-NPs and Se-NPs. The 16S rRNA sequence analysis of Streptomyces S91 revealed that S91 had a high similarity (98.82%) to Streptomyces olivaceous. The biosynthesized Au-NPs and Se-NPs were characterized using a UV-Vis spectrophotometer, dynamic light scattering, transmission electron microscopy, energy dispersive X-ray diffraction and Fourier-transform infrared spectroscopy. The quorum sensing inhibitory (QSI) potential of Au-NPs and Se-NPs and the antivirulence activity was examined against P. aeruginosa. The QSI potential was confirmed using RT-PCR. The synthesized Au-NPs and Se-NPs were monodispersed spherical shapes with particle size of 12.2 and 67.98 nm, respectively. Au-NPs and Se-NPs eliminated QS in P. aeruginosa at a concentration range of 2.3–18.5 µg/mL for Au-NPs and 2.3–592 µg/mL for Se-NPs. In addition, Au-NPs and Se-NPs significantly inhibited QS-related virulence factors, such as pyocyanin, protease and, elastase in P. aeruginosa. At the molecular level, Au-NPs and Se-NPs significantly suppressed the relative expression of QS genes and toxins. Hence, the biosynthesized Au-NPS and Se-NPS could be substantial inhibitors of QS and virulence traits of P. aeruginosa.
Highlights
The spread of antibiotic-resistant bacteria, both in hospitals and in communityacquired infections, is one of the major problems of antibiotic therapy [1]
Antibiotics that are currently available are ineffective against pandrug-resistant pathogens, and antibiotic combinations are required in systemic infections
A total of twenty-five actinomycetes isolates were purified from eight soil samples; six agriculture soils were collected from the Dakahlia governorate, and two sand soils were collected from the Damietta governorate (Supplementary Table S1)
Summary
The spread of antibiotic-resistant bacteria, both in hospitals and in communityacquired infections, is one of the major problems of antibiotic therapy [1]. Resistance to colistin, a last resort treatment, has been reported globally, increasing the risk of infections caused by untreatable bacteria. Antibiotics that are currently available are ineffective against pandrug-resistant pathogens, and antibiotic combinations are required in systemic infections. The development of resistance to antimicrobial agents forces the administration of high doses of antibiotics, with adverse and toxic effects. This strengthens the need for novel therapeutic drugs [4]
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