Endophytic bacterial metabolites from Anacardium humile combined with essential oils in solution blow spun fibers for antimicrobial wound dressings

Skin wounds represent a major entry point for microbial colonization and frequently lead to infections that may progress to systemic complications if left untreated. Although antibiotics have been employed to treat such infections, their extensive use has contributed to the growing problem of antimicrobial resistance. Consequently, natural bioactive compounds, such as metabolic extracts from endophytic bacteria and essential oils, have emerged as promising alternatives in the efforts against multidrug resistance. Here we investigated antimicrobial formulation based on endophytic bacteria isolated from Anacardium humile, a plant native to the Brazilian Cerrado, combined with essential oils and incorporated into polymeric fibers. To this end, endophytic bacteria were isolated from branches and leaves of Anacardium humile, and the two most antagonistic strains against E. coli, S. aureus, and C. albicans were taxonomically identified as B. subtilis and B. amyloliquefaciens. The optimization of bacterial metabolic extracts (ME) production from these endophytic bacteria were used to develop natural antimicrobial formulations by combining the bacterial ME with clove and limonene essential oils (EO), resulting in formulations that demonstrated antimicrobial effects against the tested pathogens. These ME-EO formulations were encapsulated within fibers of a biodegradable poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blend using the solution blow spinning technique, thereby producing antimicrobial wound dressings. The resultant fiber-based wound dressings demonstrated both inhibition halos formation and contact-based antimicrobial activity against the pathogens studied. Furthermore, the as-produced ME-EO-fibers exhibited significantly reduced cytotoxicity toward fibroblast cells compared with the non-encapsulated natural antimicrobial formulations. These results highlight the potential of combining endophytic bacterial metabolites and essential oils within polymeric fibers as a strategy for the development of bioactive wound dressings.