Silver nanoparticles formation by extracellular polymeric substances (EPS) from electroactive bacteria.

Area of Science:

• Environmental microbiology
• Nanotechnology
• Biochemistry

Background:

• Microbial extracellular polymeric substances (EPS) are complex biopolymer mixtures vital for metal transport.
• Electroactive bacteria utilize minerals for energy, playing key roles in environmental processes.
• Silver nanoparticles (AgNPs) have diverse applications but require efficient synthesis methods.

Purpose of the Study:

• To investigate the potential of microbial EPS from electroactive bacteria in reducing silver ions (Ag+) to silver nanoparticles (AgNPs).
• To characterize the synthesized AgNPs and identify the components within EPS responsible for the reduction process.

Main Methods:

• Extraction of EPS from three electroactive bacterial strains: Shewanella oneidensis, Aeromonas hydrophila, and Pseudomonas putida.
• Characterization of AgNPs using UV-visible spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy.
• Analysis of EPS composition to identify key components involved in Ag+ reduction.

Main Results:

• All three microbial EPS successfully reduced Ag+ to form AgNPs.
• Characterization confirmed the formation and properties of the synthesized AgNPs.
• Cytochrome c was identified as a significant component in the EPS, contributing to the reduction of Ag+.

Conclusions:

• EPS from electroactive bacteria serve as effective natural reductants for AgNPs synthesis.
• This study provides insights into the biogenic synthesis of metal nanoparticles and their environmental fate.
• The findings highlight a sustainable approach for nanoparticle production using microbial biomaterials.