Bioactive films for the control of skin pathogens with sophorolipids from Starmerella bombicola

Cutaneous infections involve microbial invasion of pathogens into the skin layers and can lead to mild cases and severe life-threatening conditions. Biopolymeric films could be used to treat cutaneous infections and also meet the demand of the consumers for new biological-based products obtained from renewable sources. Sophorolipids are antimicrobial biosurfactants produced by the yeast Starmerella bombicola with great potential for application by pharmaceutical and cosmetic industries. The aim of this study was to produce and to characterize biodegradable films based on cassava starch, pullulan and sophorolipids for the control of skin pathogens, with and without the presence of citric acid as a crosslinking agent. Films were obtained by the casting method, and eight formulations were prepared using different concentrations of sophorolipids (0, 2.5, 5.0 and 10.0%-g/100 g polymer), with and without citric acid. The results showed that the addition of sophorolipids resulted in more opaque surfaces, forming homogeneous structures observed by scanning electron microscopy. Addition of citric acid resulted in films with higher flexibility, lower solubility and water vapor permeability values. The films containing sophorolipids in all concentrations were able to inhibit 100% of the growth of Staphylococcus aureus and Staphylococcus epidermidis. These findings lead to the possibility of developing new, sustainable, and natural antimicrobial sophorolipid films to treat bacterial skin infections.

Automated summary

This study aims to develop biodegradable films based on cassava starch, pullulan, and sophorolipids for the treatment of skin infections. By adding sophorolipids and citric acid, the properties of the films were modified, resulting in antimicrobial effects. The results of the study show that these films can inhibit the growth of common skin pathogens.