Antimicrobial and cytotoxic activity of silver nanoparticles synthesized from two haloalkaliphilic actinobacterial strains alone and in combination with antibiotics.

Presently, the effective antimicrobial agents have been limited by the emergence of microbial strains with multidrug resistance and biofilm formation potential. In the present study, we report remarkable antimicrobial activity of silver nanoparticles (AgNPs) synthesized from Streptomyces calidiresistens IF11 and IF17 strains, including inhibition of biofilm formation and synergistic effect of AgNPs and antibiotics against selected bacteria and yeasts. Cytotoxic effect of AgNPs on mammalian cell lines was also evaluated. Analysis of biosynthesized AgNPs by Fourier Transform Infrared Spectroscopy and transmission electron microscopy revealed their spherical shape, small size in the range of 5-50 and 5-20 nm, respectively, as well as the presence of capping agents. Study of antimicrobial activity of AgNPs against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Candida albicans and Malassezia furfur evaluated by minimum inhibitory concentration (MIC) and minimum biocidal concentration (MBC) assays revealed that MICs of AgNPs from IF11 and IF17 strains against bacteria and yeasts were found to be in the range of 16-128 and 8-256 μg ml-1 , while MBCs were in the range of 48-192 and 32-256 μg ml-1 respectively. AgNPs inhibited biofilm formation of microbial strains, which was tested by using crystal violet stain. The highest synergistic effect determined by fractional inhibitory index of AgNPs with antibiotic (kanamycin or tetracycline) was found against Staph. aureus; while in case of yeasts, M. furfur showed highest sensitivity to AgNPs-ketoconazole combination (FIC = 0·12). The cytotoxic activity of AgNPs towards HeLa and 3T3 cell lines was studied by MTT assay. The IC50 of AgNPs estimated against mouse fibroblasts was found to be 8·3 and 28·3 μg ml-1 and, against HeLa cell line, 28·5 and 53·8 μg ml-1 respectively. It can be concluded that AgNPs synthesized from S. calidiresistens IF11 and IF17 strains have potential as an effective antimicrobial and cytotoxic agent, especially when used in combination with antibiotics/antifungal agents. This study indicates potential application of biogenic silver nanoparticles as an antimicrobial agent in nanomedicine.

Wypij M ，Świecimska M ，Czarnecka J ，Dahm H ，Rai M ，Golinska P ... -  《-》

Synthesis, characterization and evaluation of antimicrobial and cytotoxic activities of biogenic silver nanoparticles synthesized from Streptomyces xinghaiensis OF1 strain.

Wypij M ，Czarnecka J ，Świecimska M ，Dahm H ，Rai M ，Golinska P ... -  《-》

Silver nanoparticles from Pilimelia columellifera subsp. pallida SL19 strain demonstrated antifungal activity against fungi causing superficial mycoses.

In this study, we present the in vitro antifungal activity of silver nanoparticles (AgNPs) synthesized from acidophilic actinobacterium Pilimelia columellifera subsp. pallida SL19 strain, alone and in combination with antibiotics viz., amphotericin B, fluconazole, and ketoconazole against pathogenic fungi, namely Candida albicans, Malassezia furfur, and Trichophyton erinacei. The minimum inhibitory concentration (MIC) and minimum biocidal concentration (MBC) of AgNPs against test fungi were evaluated. The fractional inhibitory concentration (FIC) index was determined to estimate antifungal activity of AgNPs combined with antibiotics. Antifungal activity of AgNPs varied among the tested fungal strains. M. furfur was found to be most sensitive to biogenic silver nanoparticles, followed by C. albicans and T. erinacei. The lowest MIC of AgNPs was noticed against M. furfur (16 μg ml-1 ). Synergistic effect was observed on C. albicans when AgNP were combined with amphotericin B and ketoconazole and on M. furfur with fluconazole and ketoconazole (FIC index of 0.5). Cytotoxic effect of AgNPs on HeLa and 3T3 cell lines was evaluated. The IC50 values were found to be 55 and 25 μg ml-1 , respectively. The present study indicates that silver nanoparticles from P. columellifera subsp. pallida SL19 strain have antifungal activity, both alone and in combination with antibiotics, and offer a valuable contribution to nanomedicine.

Wypij M ，Czarnecka J ，Dahm H ，Rai M ，Golinska P ... -  《-》

Cytotoxic and Antimicrobial Efficacy of Silver Nanoparticles Synthesized Using a Traditional Phytoproduct, Asafoetida Gum.

The present study synthesized silver nanoparticles (AgNPs) using the aqueous extract of a traditional medicinal product consisting of an oleoresin (a combination of macromolecules of carbohydrates and proteins) exuded from the rhizome of the plant Ferula foetida (asafoetida gum) and evaluated its biological properties. The silver nanoparticles synthesized using asafoetida gum (As-AgNPs) were characterized using UV/Vis spectroscopy, fourier infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM) and EADX. The cytotoxicity and antimicrobial activity As-AgNPs were evaluated against MCF-7 cell lines and selected microbial pathogens, respectively. The synthesized silver nanoparticles were crystalline in nature with a spherical shape. The average particle size was 5.6-8.6 nm. The cytotoxicity of the synthesized As-AgNPs was evaluated against MCF-7 cell lines, and the As-AgNPs were found to be effective in inhibiting the multiplication of cancer cells. The As-AgNPs exhibited significant antimicrobial activity towards E. coli, K. pneumoniae and C. albicans. The MIC of the synthesized As-AgNPs was 7.80 μg/mL for E. coli ATCC 25922, Salmonella sp. WS50- and S. typhi; 15.60 μg/mL for S. typhimurium and S. aureus WS10, and 31.20 μg/mL for K. pneumoniae and S. aureus ATCC 43300-MRSA. In addition, MIC values of 15.60 μg/mL for C. albicans ATCC8436 and 31.20 μg/mL for C. krusei ATCC6258 were obtained. As asafoetida is a good traditional medicine, its involvement in the synthesis of AgNPs led the silver nanoparticles to exhibit good cytotoxic and antimicrobial effects.

Devanesan S ，Ponmurugan K ，AlSalhi MS ，Al-Dhabi NA ... -  《International Journal of Nanomedicine》

Synthesis of silver nanoparticles from two acidophilic strains of Pilimelia columellifera subsp. pallida and their antibacterial activities.

Biosynthesis of silver nanoparticles (AgNPs) is an eco-friendly approach by using different biological sources; for example, plants and microorganisms such as bacteria, fungi, and actinobacteria. In this report, we present the biological synthesis of silver nanoparticles (AgNPs) by acidophilic actinomycetes SL19 and SL24 strains isolated from pine forest soil (pH < 4.0). The isolates based on 16S rRNA gene sequence were identified as Pilimelia columellifera subsp. pallida. The synthesized AgNPs were characterized by visual observations of colour change from light-yellow to dark-brown. The UV-vis spectra of AgNPs were recorded at 425 and 430 nm. The AgNPs were further characterized by Nanoparticle tracking analysis (NTA), Zeta potential, Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). FTIR analysis revealed the presence of proteins as a capping agent. TEM analysis confirmed the formation of spherical and polydispersed NPs of 12.7 and 15.9 nm sizes. The in vitro antibacterial activity of AgNPs alone and in combination with antibiotics was evaluated against clinical bacteria viz., Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and uropathogens such as Enterobacter, S. aureus, P. aeruginosa, K. pneumoniae, and E. coli. The lowest MIC (40 μg ml(-1) ) was demonstrated by AgNPs synthesized from SL24 against E. coli. However, the AgNPs of SL19 showed lowest MIC (70 μg ml(-1) ) against S. aureus. The activity of antibiotic was enhanced, when tested in combination with silver nanoparticles synthesized from both actinobacterial strains.

Golińska P ，Wypij M ，Rathod D ，Tikar S ，Dahm H ，Rai M ... -  《-》