Isolation of Soil Microorganisms for the Synthesis of Gold and Silver Nanoparticles for Antimicrobial Applications

The isolation of soil microorganisms with the ability to produce antibiotics and other bioproducts represents a key approach for harnessing microbial diversity and discovering biologically significant compounds. Filamentous fungi, which are commonly found in soil, produce substances and compounds rich in biomolecules that function as reducing and stabilizing agents in the synthesis of inorganic nanoparticles (NPs) such as gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs). These nanoparticles play a crucial role in enhancing the efficacy of antibiotics by improving drug delivery, increasing bacterial targeting, and combating resistance mechanisms.

This study investigates the efficacy of filamentous fungi isolated from soil samples in producing antimicrobial compounds, as well as their ability to synthesise AuNPs and AgNPs, with the aim of developing new next-generation antibiotics. The isolated fungi were tested for antimicrobial activity using the agar-well diffusion method against pathogenic bacterial strains. The fungi showing the most promising antimicrobial results were identified through DNA sequencing, and their capability to synthesize NPs was explored by exposing the extracellular extract to chloroauric acid or silver nitrate.

The results demonstrated promising minimum inhibitory concentration (MIC) values against pathogenic bacteria, including Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Pseudomonas aeruginosa. The follow-up work involves the characterization of antimicrobial compounds and NPs, along with further optimization of their use.

This study underscores the importance of exploiting fungi isolated from soil to discover novel antimicrobials and highlights the advancement of green nanoparticle synthesis as crucial for creating next-generation antibiotics. This approach aims to minimize ecological harm while addressing antibiotic resistance.