Bioadhesive Polymeric Films Containing Rhamnolipids, An Innovative Antimicrobial Topical Formulation.

Acne affects most of the world's population, causing an impact on the self-esteem of adolescents and young adults. One of the causes is the presence of the bacteria Cutibacterium acnes which are part of the natural microbiota of the skin. Topical treatments consist of anti-inflammatory and antibiotics, which could select resistant strains. Alternatives to the antibiotic are biocomposites that have antimicrobial activity like biosurfactants which are produced by bacteria. An innovative way of applying these compounds is bioadhesive polymeric films that adhere to the skin and release the active principle topically. Rhamnolipids have great potential to be used in the treatment of acne because they present antimicrobial activity against C. acnes in low and safe concentrations (MIC of 15.62 µg/mL, CBM of 31.25 µg/mL and CC50 of 181.93 µg/mL). Four films with different rhamnolipids concentrations (0.0; 0.1; 0.2; and 0.3%, w/w) were obtained as to visual appearance, mass variation, thickness, density, solubility, pH, water vapor transmission, mechanical properties (folding endurance, bioadhesion strength, tensile strength, elongation at break and Young's modulus), scanning electron microscopy and infrared. The results show that these formulations had a homogeneous appearance; elastic mechanical properties; pH similar to human skin and bioadhesive. The polymeric films containing rhamnolipids were effective against C. acnes, in the in vitro test, at the three concentrations tested, the film with the highest concentration (0.3%, w/w) being the most promising for presenting the highest antimicrobial activity. Thus, the polymeric film containing rhamnolipids has the potential to be used in the treatment of acne.

ß-(1 → 3)-Glucanolytic yeasts from Brazilian grape microbiota: production and characterization of ß-glucanolytic enzymes by Aureobasidium pullulans 1WA1 cultivated on fungal Mycelium.

A total of 95 yeast strains were isolated from the microbiota of different grapes collected at vineyards in southern Brazil. The yeasts were screened for ß-(1 → 3)-glucanases using a newly developed zymogram method that relies upon the appearance of clearance zones around growing colonies cultured on agar­botryosphaeran medium and also by submerged fermentation on nutrient medium containing botryosphaeran, a (1 → 3),(1 → 6)-ß-d-glucan. Among 14 ß-(1 → 3)-glucanase-positive yeasts identified, four strains produced the highest ß-glucanolytic activities and were evaluated for enzyme production on cellobiose, botryosphaeran, and mycelial biomass from Botryosphaeria rhodina (MAMB-05). Yeast strain 1WA1 produced the highest ß-(1 → 3)-glucanase and ß-glucosidase activities and was identified by molecular characterization as Aureobasidium pullulans. The physicochemical properties of the crude ß-glucanolytic enzyme preparation were characterized, and the preparation was used to hydrolyze several ß-d-glucans (laminarin, botryosphaeran, lasiodiplodan, pustulan, and curdlan). The production and physicochemical properties of the ß-glucanolytic preparation enable its potential applications in wine enology and production of prebiotics through hydrolysis of ß-d-glucans.