Intracellular and extracellular biosynthesis, characterization, and antimicrobial and antibiotic removal activities of silver nanoparticles produced by Trichoderma viride.

Biosynthesis offers an environmentally sustainable approach for producing organic-modified nanomaterials, which exhibit significant potential in biomedicine, anticancer therapies, and antimicrobial applications. The influence of nutritional conditions on the physiological functions and biosynthetic capabilities of microorganisms is profound and critical. This study investigates the modulation of intracellular and extracellular biosynthesis of silver nanoparticles (AgNPs) by altering the nutritional environment of the fungus Trichoderma viride (T. viride). The mechanisms of AgNP biosynthesis are elucidated using tilted scanning transmission electron microscopy, cryo-transmission electron microscopy, and protein expression analysis. Results show that organic-rich conditions enhance the adsorption, reduction, and nucleation of silver ions at the cell surface, correlating with significant upregulation of reductive proteins. In contrast, inorganic salt-based conditions promote reduction and nucleation within the cell, leading to increased proteins associated with vesicular transport and Golgi apparatus, resulting in exocytosis. Antimicrobial assays against Escherichia coli, Bacillus subtilis, and Shewanella sp. demonstrate differing efficacies of intracellular versus extracellular synthesized AgNPs under these conditions. This research highlights the effectiveness of biosynthesized AgNPs in removing antibiotic contaminants from aquatic environments, achieving nearly 100 % removal rates. These findings enhance our understanding of the complex physiological processes involved in biosynthesis and underscore the environmental application potential of biosynthetic nanomaterials.