Acinetobacter sp. mediated synthesis of AgNPs, its optimization, characterization and synergistic antifungal activity against C. albicans

Abstract

Aims To synthesize silver nanoparticles (AgNPs) with cell free extract of Acinetobacter sp. and evaluate antifungal activity against planktonic and biofilm of Candida. Also, to study mechanism of antifungal action of AgNPs. Methods and Result Acinetobacter spp were screened for synthesis of AgNPs. Physio‐chemical parameters were optimized to obtained monodispersed nanoparticles. Optimized nanoparticles were characterized using spectroscopic, microscopic and diffraction techniques. Antifungal and biofilm disruption activity of AgNPs (10 ± 5 nm) were investigated against C. albicans. Mechanism of antifungal activity of nanosilver was deduced by growth curve, reactive oxygen species generation, thiol interaction and microscopic analysis. Acinetobacter sp. GWRFH 45 gave maximum synthesis of AgNPs. At optimized condition monodispersed, spherical nanoparticles were obtained which were crystalline with negative surface charge. AgNPs exhibited antifungal activity against planktonic cells and biofilm of Candida. AgNPs showed synergistic effect with amphotericin B as well as fluconazole against biofilm disruption. AgNPs were found to affect growth of Candida, generate reactive oxygen species and disrupt cellular morphology. Conclusions Cell free extract of A. calcoaceticus GWRFH 45 has ability to synthesize AgNPs. AgNPs alone and in combination with drugs have potential to inhibit C. albicans. Significance and Impact of the Study This is the first report of bacteriogenic AgNPs used in combination with antifungal drugs against Candida.

Silver nanoantibiotics display strong antifungal activity against the emergent multidrug-resistant yeastCandida aurisunder both planktonic and biofilm growing conditions

“…We note that the AgNPs IC50 value for the C. auris AR #0390 strain is higher than the value reported for the same strain as reported by Lara et al (1.1 μg mL -1 vs 0.06 μg mL -1 , respectively), which is most likely related to the different techniques used for the synthesis of these nanoantibiotics resulting in AgNPs with different characteristics. Also, the antibiofilm activity of our AgNPs is comparable to the activity described for AgNPs synthesized using different methods against other Candida species [29,34,35].…”

“…For the C. auris AR strains #0383, #0386, and #0390, the AgNPs anti-biofilm activity is superior to the activity of Fluconazole (range from >64 to >1024 μg mL -1 ) and Caspofungin (>16 μg mL -1 ). Furthermore, the AgNPs potency parallels to the activity of Amphotericin B (1 to > 8 μg mL -1 ) [34,39]. Overall, although multiple mechanisms confer resistance of cells within biofilms against conventional antifungal agents [40], our results suggest that these do not equally affect the anti-biofilm activity of AgNPs.…”

Silver Nanoantibiotics Display Strong Antifungal Activity Against the Emergent Multidrug-Resistant Yeast Candida auris Under Both Planktonic and Biofilm Growing Conditions

“…We note that the AgNPs IC 50 value for the C. auris AR #0390 strain is higher than the value reported for the same strain as reported by Lara et al (2015) (1.1 vs. 0.06 μg ml −1 , respectively), which is most likely related to the different techniques used for the synthesis of these nanoantibiotics resulting in AgNPs with different characteristics. Also, the antibiofilm activity of our AgNPs is comparable to the activity described for AgNPs synthesized using different methods against other Candida species (Lara et al, 2015;Muthamil et al, 2018;Nadhe et al, 2019).…”

“…For the C. auris AR strains #0383, #0386, and #0390, the AgNPs antibiofilm activity is superior to the activity of fluconazole (range from >64 to >1,024 μg ml −1 ) and caspofungin (>16 μg ml −1 ). Furthermore, the AgNPs potency parallels the activity of amphotericin B (1->8 μg ml −1 ) (Dekkerová et al, 2019;Nadhe et al, 2019). Overall, although multiple mechanisms confer resistance of cells within biofilms against conventional antifungal agents (Srinivasan et al, 2014), our results suggest that these do not equally affect the anti-biofilm activity of AgNPs.…”

Bismuth nanoparticles obtained by a facile synthesis method exhibit antimicrobial activity againstStaphylococcus aureusandCandida albicans

“…When compared to antifungal agents. The activity of BiNPs is better than Fluconazole (IC 50 >1024 µg mL -1 ), but lower than Amphotericin B (IC 50 >1 µg mL -1 ) and the echinocandins [56,57].…”