Silver Nanoparticles Conjugated with BK510Lys Endolysin for Gram-Negative Bacteria Inhibition

Abstract

In the last decade, the problems caused by the excessive use of antibiotics and the emergence of multi-resistant patterns in Gram-negative bacteria caused the generation of several alternatives and/or replacements, including endolysins and the use of silver nanomaterials (AgNPs). It has been shown that the AgNPs help overcome the bacterial lipopolysaccharide barrier and allow the endolysins to reach the cell wall; therefore, in the present investigation, conjugates of BK510 commercial endolysins (BK510Lys) with metallic nanoparticles were made, which eliminated the obstacle that represents the outer membrane of Gram-negative bacteria. AgNPs were produced by green synthesis using Lepidium virginicum extract as a reducing agent, and diameters of 16.06 ± 4.23 nm were obtained. The endolysins BK510Lys and AgNPs were used to generate conjugates that were characterized and evaluated against gram-negative and gram-positive bacteria of veterinary interest. The results indicated that using the conjugates at a concentration of 0.01 mg/mL, a 2:1 ratio, a temperature of 40 °C, and at pH 5, the inhibitory effect was greater than that of AgNPs (0.5 µg/mL) in more than 65% of the Gram-negative bacteria analyzed. Furthermore, it was determined that for both BK510Lys and the AgNP-BK510Lys conjugate, the only factor that had a significant effect on the lytic activity was their concentration. Finally, we concluded that based on the promising results obtained, future follow-up can be conducted for the formulation of highly specific alternative drugs for super-resistant Gram-negative bacteria.

Keywords

• silver-nanoparticles
• antibacterial
• green-synthesis
• endolysins