Antimicrobial and Antioxidant Activity of Rhamnolipids Biosurfactant is Produced by Pseudomonas aeruginosa

Abstract

Rhamnolipids are the glycolipid biosurfactant produced by different Pseudomonas species; they show antimicrobial activity and antioxidant. The findings of antimicrobial activity showed the rhamnolipid biosurfactant had an antimicrobial effect against the microorganisms at different concentrations, such as toward Bacillus cereus and Klebsiella pneumoniae, while a lower inhibitory effect toward Staphylococcus aureus and Pseudomonas aeruginosa. The rhamnolipid biosurfactant was shown to have a lower inhibitory effect against fungal strains Candida albicans and Aspergillus niger. The lower minimum inhibitory concentration (MIC) values of rhamnolipid biosurfactant toward the investigated microorganisms were 2 mg/ml for E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa and 3 mg/ml for Staphylococcus aureus, Enterobacter cloacae, Bacillus cereus, Proteus mirabilis, Candida albicans and Aspergillus niger. Rhamnolipid biosurfactant was tested as an antioxidant agent; the results showed 22.7 %, 47.4 %, 79.8 %, 85 % and 91.4 % of antioxidant activity at concentrations 5, 10. 15, 20 and 25 mg/ml, respectively. Cytotoxicity of the rhamnolipid biosurfactant was also examined at different concentrations against human erythrocytes. Hemolysis of the erythrocytes was observed at concentrations 100, 75, 50, 40 and 35 mg/ml, whereas the results exhibited no hemolysis at concentrations 25 and 15 mg/ ml. The study concluded that rhamnolipid biosurfactant showed effective antioxidant activity, no hemolysis at lower concentrations and has a high antimicrobial effect. The rhamnolipid biosurfactant is a suitable and great alternative to be employed as an effective and safe therapeutic agent. Keywords: Antimicrobial; Antioxidant; Cytotoxicity; Rhamnolipid; Pseudomonas aeruginosa