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Biosurfactants are surfactants biologically produced by microorganisms, presenting several advantages when compared to synthetic surfactants. Pseudomonas aeruginosa is known for producing rhamnolipids, considered one of the most interesting types of biosurfactants due to their high yields, when compared to other types. In this work, the production of rhamnolipid from P. aeruginosa was optimized. At first, the Plackett–Burman design was used to select most significant variables affecting the biosurfactant production yield among nine variables—carbon–nitrogen ratio, carbon concentration, nitrogen source, pH, cultivation time, potassium and magnesium concentrations, agitation, and temperature. Then, using main variables, a central point experimental design aiming to optimize rhamnolipid production was performed. The maximum biosurfactant concentration obtained was 0.877 mg L−1. The rhamnolipid also displayed a great emulsification rate, reaching approximately 67%, and the ability to reduce water surface tension from 72.02 to 35.26 mN m−1 at a critical micelle concentration (CMC) of 127 mg L−1, in addition to presenting a good stability when exposed to wide pH and salinity ranges. The results suggest that rhamnolipids are promising substitutes for synthetic surfactants, especially due to lower impacts on the environment. [ABSTRACT FROM AUTHOR]

Previously, mucus of some molluscs has been studied as a potential source of new natural compounds capable of inducing cell proliferation and of remodelling tissue. Here, the focus of the study is possible use of mucus released by Phyllocaulis boraceiensis - a compound inducing cell proliferation and enhancing collagen synthesis in dermal fibroblasts and inducing proliferation human endothelial cell cultures. Fibroblasts treated with P. boraceiensis mucus at concentrations below 0.012 μg/μl developed high rates of proliferation, as evaluated using MTT assay; the proliferative effect was dose-dependent. Production and secretion of extracellular matrix components and collagen type I fibres were enhanced after 24 h of treatment, revealing a hormesis effect, biphasic dose response - low dose for proliferation yet toxic at high dose. No significant change in proliferation was observed in treated endothelial cells and production of lipid polyunsaturated free radicals was low in both cell types. Treatment with P. boraceiensis mucus produced pronounced changes in fibroblast cell number and morphology, and in quantities of well-ordered collagen deposition. These results support the premise that Phyllocaulis boraceiensis mucus demonstrates proliferative properties in cells involved in the healing process. [ABSTRACT FROM AUTHOR]