Physicochemical and Antimicrobial Properties of New Rhamnolipids Produced by <i>Pseudomonas </i><i>a</i><i>eruginosa</i> AT10 from Soybean Oil Refinery Wastes

The rhamnolipids produced by Pseudomonas aeruginosa strains are often a mixture of several homologues. Up to seven (R2C10C10 + R1C10C10 + R2C10C12 + R1C10C12 + R1C12:1C10 + R1C12:2 + R1C8:2 ) have been identified in cultures of P. aeruginosa AT10 from soybean oil refinery wastes. This study deals with the production, purification, and identification of rhamnolipids in the mixture (M7), as well as their physical and chemical characterization and the evaluation of their antimicrobial properties. The surface tension decreases to 26.8 mN/m and the critical micelle concentration value to 1.2 × 102 mg/L. These molecules show excellent antifungal properties against Aspergillus niger and Gliocadium virens (16 μg/mL) and C. globosum, P. crysogenum, and A. pullulans (32 μg/mL), whereas the growth of the phytopathogenic fungi B. Cinerea and R. solani was inhibited at 18 μg/mL.