Characterization, cytotoxicity, and genotoxicity properties of novel biomediated nanosized-silver by Egyptian Streptomyces roseolus for safe antimicrobial applications

Asmaa Elnady,Rateb N Abbas,Noha M Sorour

doi:10.1007/s11274-022-03231-6

Abstract

Multi-drug resistant bacteria are not effectively managed with current treatments, making it a serious global problem. Therefore, there is an essential need for finding new antimicrobial agents. In this regard, silver nanoparticles (Ag-NPs) have been projected as a new generation of antimicrobial agents. Ag-NPs were biomediated by Egyptian Streptomyces roseolus for the first time, which was molecularly identified using 16S rRNA sequencing under accession no. MT071505. Biosynthesized Ag-NPs were characterized using UV–Vis spectroscopy, XRD, TEM, FTIR, and DLS. FTIR analysis confirmed the presence of different bioactive functional groups, such as N–H, C–H, C–O–C, C–NH2, and C=O acting as bioreducing/stabilizing agents for Ag-NPs. Ag-NPs exhibited antimicrobial activity against some multi-drug resistant Gram-positive and Gram-negative pathogens. MBC of Ag-NPs against Listeria monocytogenes and Klebsiella pneumonia were 0.195 and 0.048 mg/mL, respectively, with a tolerance level of 2 confirming its biocidal effect. SEM imaging of Ag-NPs-treated L. monocytogenes and K. pneumonia showed shrunk destroyed cells after 6 h of treatment. Biosynthesized Ag-NPs exhibited IC50 of < 0.3 and 8.21 mg/mL, on normal Human Skin Fibroblast, and Blood Lymphocytes, respectively. IC50 values were significantly higher than its MBC values, with no harmful cytotoxic effect, thus can be safely applied at its biocidal concentration. For biosafety purposes, the genotoxicity of biosynthesized Ag-NPs was assessed using Comet assay for the first time on Blood Lymphocytes, with zero-tail and 100% head intensity indicating non-genotoxic effect. An ecofriendly biomediated synthesis of Ag-NPs was described with easy scale-up, non-toxic by-products, so, it can be recommended as a powerful-safe antimicrobial agent.Graphical abstract

Highlights

Multi-drug resistant bacteria are not effectively managed with current treatments, making it a serious global problem for public health
The antibiotic resistance pattern among patients showed the prevalence of methicillin-resistant S. aureus (MRSA), extended-spectrum beta-lactamase bacteria, Cephalosporin resistant K. pneumoniae, Carbapenem resistant K. pneumonia, and the multidrug resistant-P. aeruginosa, E. coli, and Acinetobacter baumannii spp. (Fakhr and Fathy 2018; Hassan et al 2021)
Streptomyces roseolus was isolated from the Egyptian soil and molecularly identified using 16S rRNA gene sequencing

Summary

Introduction

Multi-drug resistant bacteria are not effectively managed with current treatments, making it a serious global problem for public health. The increasing incidence of multidrug-resistant pathogens responsible for nosocomial infections has been detected in different health-care facilities in Egypt, where, Gram-negative bacteria were the most common pathogens (Saied et al 2011; Fakhr and Fathy 2018; Hassan et al 2021). Metallic nanoparticles (NPs) have gained great significance in the modern era of nanomaterials because of their unique intrinsic properties based on their morphology, size, and distribution (El‐Baz et al 2016; Mourdikoudis et al 2018). These new properties are excellent physicochemical, electrical conductivity, catalytic, and mechanical stability (Srikar et al 2016; Hassan et al 2019; Crisan et al 2021). Ag-NPs have been exploited for various applications, in household and healthcare-related products, wound dressings, medical device coatings, and cosmetics (Zhang et al 2016; Wypij et al 2018; Vanlalveni et al 2021)

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