Biosurfactants as Stabilizers of Silver Nanoparticles: A Sustainable Approach for Antimicrobial Applications

Microbial resistance to conventional antimicrobials is a growing public health challenge, driving the search for effective and sustainable alternatives. Among emerging strategies, the combination of silver nanoparticles (AgNPs), recognized for their potent antimicrobial action, with biosurfactants, natural, biodegradable compounds capable of interacting with microbial cell membranes and promoting their stabilization stands out. In this context, the aim of this study was to produce a biosurfactant by Candida glabrata UCP 1002 from agroindustrial residues, reducing costs and environmental impacts. The compound exhibited a surface tension of 29 mN/m, a critical micellar concentration of 0.3%, and a yield of 9 g/L; furthermore, it demonstrated stability across wide ranges of temperature, pH, and salinity. The AgNPs were synthesized using the biosurfactant as a stabilizing agent and ascorbic acid as a reducing agent, resulting in stable particles. In antimicrobial assays, the formulation inhibited Gram-positive microorganisms, Gram-negative microorganisms, and fungi. The best results were obtained against Pseudomonas aeruginosa (26.63%) and Candida albicans (28.11%), followed by Staphylococcus aureus (17.58%), Enterobacter sp. (14.42%), and Escherichia coli (13.68%). Although less effective than commercial antibiotics such as streptomycin and moxifloxacin, it showed potential as a complementary alternative in combating multidrug-resistant pathogens. Cytotoxicity assays revealed low toxicity toward normal cells (28.42% inhibition in Vero CCL-81) and minimal activity against tumor cells. The results demonstrate that the BS-AgNPs association combines relevant antimicrobial activity with environmental safety and biocompatibility, establishing itself as a promising and sustainable approach for application in health, industry, and the environment, with potential for scale-up production from low-cost raw materials.