Antimicrobial properties of silver nanoparticles prepared by Acacia etbaica (Schweinf.) valve extract

[Display omitted] •AgNPs are bio-synthesized using Acacia etbaica valve extract.•This method was very fast, simple and environmental friendly.•Antimicrobial activity against human pathogenic microbes was efficaciously investigated.•AgNPs are not effective against E. Faecalis and P. aeruginosa.•The prepared AgNPs are more potent against specific microbe than their crude extract. Here, we employed green and very fast (clock) synthesis of silver nanoparticles (AgNPs) by means of silver nitrate and Acacia etbaica valve extract at room temperature. Transmission electron microscopy (TEM) results confirm the spherical shape and diameter (size) ranging from 6.38 ± 3.21, 10.09 ± 3.21 and 20 ± 3.21 for AeAg-1, AeAg-2 and AeAg-3, respectively. TEM results showed that size of AgNPs increase as the concentration of AgNO3 decreases due to the low concentration of bio reducing agent present in the extract. The enhanced antimicrobial activity against human pathogenic microbes was investigated by diffusion method based on zone of inhibition. The prepared AgNPs showed high specificity against the tested pathogens, namely K. pneumonia, S. typhi, S. dysenteriae, P. mirabilis, S. saprophyticus, S. aureus and C. albican with inhibition zone between 22.3 ± 2.08 mm and 11.67 ± 1.15 mm. On the other hand, the prepared AgNPs did not exhibit high specifity against E. Faecalis and P. aeruginosa. Therefore, it can be concluded that the prepared AgNPs have potential as natural antimicrobial agents against microbes with multidrug resistance.