Biosynthesis of silver nanoparticles using Burkholderia contaminans ZCC and mechanistic analysis at the proteome...

The biogenic synthesis of silver nanoparticles (AgNPs) by microorganisms has been a subject of increasing attention. Despite extensive studies on this biosynthetic pathway, the mechanisms underlying the involvement of proteins and enzymes in AgNPs production have not been fully explored. Herein, we reported that Burkholderia contaminans ZCC was able to reduce Ag⁺ to AgNPs with a diameter of (10±5) nm inside the cell. Exposure of B. contaminans ZCC to Ag⁺ ions led to significant changes in the functional groups of cellular proteins, with approximately 5.72% of the (C-OH) bonds being converted to (C-C/C-H) (3.61%) and CO (2.11%) bonds, and 4.52% of the CO (carbonyl) bonds being converted to (C-OH) bonds. Furthermore, the presence of Ag⁺ and AgNPs induced the ability of extracellular electron transfer for ZCC cells via specific membrane proteins, but this did not occur in the absence of Ag⁺ ions. Proteomic analysis of the proteins and enzymes involved in heavy metal efflux systems, protein secretion system, oxidative phosphorylation, intracellular electron transfer chain, and glutathione metabolism suggests that glutathione S-transferase and ubiquinol-cytochrome c reductase iron-sulfur subunit play importance roles in the biosynthesis of AgNPs. These findings contribute to a deeper understanding of the functions exerted by glutathione S-transferase and ferredoxin-thioredoxin reductase iron-sulfur subunits in the biogenesis of AgNPs, thereby hold immense potential for optimizing biotechnological techniques aimed at enhancing the yield and purity of biosynthetic AgNPs.