Characterization of rhamnolipid production in a pseudomonas aeruginosa strain

Abstract

Rhamnolipid is a class of glycolipid biosurfactant and has the potential to replace chemical surfactants due to its low toxicity and biodegradability. In this study, 38 Pseudomonas strains were screened for rhamnolipid production on cetyl trimethyl ammonium bromide (CTAB)-methylene blue agar plates. Among them, strain 487 was found to produce the relative high level of rhamnolipid. The rhamnolipid extract could reduce the surface tension of the medium from 67.2 to 32.7 mN/m and form stable emulsions with liquid paraffin. Strain 487 was identified as Pseudomonas aeruginosa with 16S rDNA gene sequence analysis. Rapeseed oil and glycerol were investigated for rhamnolipid production. Strain 487 produced 42.4 g/L rhamnolipid in rapeseed oil medium versus 33.4 g/L rhamnolipid using glycerol as carbon resource after 72 h fermentation. In addition, thin layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR) were performed to analyze the structure of the rhamnolipid molecule synthesized by strain.