RESUMO
Surface-active compounds (SACs) of microbial origin are an active group of biomolecules with potential use in the formulation of emulsions. In this sense, the present study aimed to isolate and select yeasts from fruits that could produce SACs for essential oil emulsions. The Candida krusei M4CK was isolated from the Byrsonima crassifolia fruit to make SACs. This emulsification activity (E24) was equal to or greater 50% in all carbon sources, such as olive oil, sunflower oil, kerosene, hexane, and hexadecane. E24 followed exponential growth according to the growth phase. The stability of emulsions was maintained over a wide range of temperatures, pH, and salinity. The OMBE4CK (melaleuca essential oil emulsion) had better and more significant inhibitory potential for biofilm reduction formation. In addition, bioemulsifier BE4CK alone on Escherichia coli and Pseudomonas aeruginosa biofilm showed few effective results, while there was a significant eradication for Staphylococcus aureus biofilms. The biofilms formed by S. aureus were eradicated in all concentrations of OMBE4CK. At the same time, the preformed biofilm by E. coli and P. aeruginosa were removed entirely at concentrations of 25 mg/mL, 12.5 mg/mL, and 6.25 mg/mL. The results show that the bioemulsifier BE4CK may represent a new potential for antibiofilm application.
RESUMO
This study aimed to evaluate the potential of lactic acid bacteria (LAB) in developing alginate-based gel formulations to inhibit Staphylococcus aureus. Initially, the antagonistic actions of three lactic acid bacteria (LAB) (Lacticaseibacillus rhamnosus ATCC 10863, Lactiplantibacillus plantarum ATCC 14917, Limosilactobacillus fermentum ATCC 23271) were evaluated against S. aureus ATCC 25923. All tested LAB inhibited S. aureus, but the highest activity was observed for L. plantarum ATCC 14917 (p < 0.05). The antimicrobial effects of L. plantarum ATCC 14917 cell suspensions, sonicate cells extract, and cell-free supernatants (pH 5 or 7) were analyzed using a broth-based assay. The cell suspensions inhibited S. aureus at concentrations ≥ 10%, and these effects were confirmed by a time-kill assay. Alginate-based gels were formulated with cell suspensions, sonicate cells extract, and cell-free supernatant (pH 5). These formulations inhibited S. aureus growth. Based on the results, the alginate gel with cell suspensions at 10% was selected for further characterization. L. plantarum ATCC 14917 survived in the alginate-based gel, especially when stored at 5 °C. At this temperature, the L. plantarum-containing alginate gel was stable, and it was in compliance with microbiological standards. These findings suggest it can be a promising agent for the topical treatment of infections induced by S. aureus.