Abstract
Pseudomonas aeruginosa EBN-8 mutant rhamnolipids produced on waste oils were investigated using normal-phase thin layer chromatography and fast atom bombardment mass spectrometry. Negative ion mode mass spectra yielded [M – H]− ions and their fragment ions, which gave some indications on the sequence of rhamnolipid biosynthesis. Five rhamnolipid homologs [viz. RC10C10 (m/z 503), RC12C10 or RC10C12 (531), RRC10C8 or RRC8C10 (621), RRC10C10 (649) and RRC12C10 or RRC10C12 (677)] were detected in four rhamnolipid combinations under the different carbon sources. The prevalence of rhamnolipids was confirmed by Fourier transform infrared and one-dimensional proton nuclear magnetic resonance. We also observed some correlations between the tensioactive characteristics and structural chemistry of the rhamnolipid surfactants.
Acknowledgments
The authors acknowledge the Director, International Center for Chemical and Biological Sciences, University of Karachi for the mass spectrometry and 1H NMR facilities and the Higher Education Commission, Islamabad for the research funds.