Molecular and structural characterization of the biosurfactant produced by Pseudomonas aeruginosa DAUPE 614.
Pseudomonas aeruginosa DAUPE 614 produced rhamnolipids (3.9gL(-1)) when cultivated on a medium containing glycerol and ammonium nitrate. These rhamnolipids reduced the surface tension of water to 27.3mNm(-1), with a critical micelle concentration of 13.9mgL(-1). The maximum emulsification index against toluene was 86.4%. The structure of the carbohydrate moiety of the glycolipid was determined by gas chromatography-mass spectroscopy (GC-MS) analysis allied to electrospray ionization mass spectrometry and nuclear magnetic resonance (NMR) 1D, 2D (13)C, (1)H spectroscopy. The hydroxyl fatty acids were analyzed by GC-MS as hydroxy-acetylated fatty acid methyl ester derivatives. The positions of the fatty acids in the lipid moiety were variable, with 6 mono-rhamnolipid homologues (Rha-C(10)-C(10); Rha-C(10)-C(8); Rha-C(8)-C(10); Rha-C(10)-C(12:1); Rha-C(12)-C(10); Rha-C(10)-C(12)) and 6 di-rhamnolipid homologues (Rha(2)-C(10)-C(10); Rha(2)-C(10)-C(8); Rha(2)-C(8)-C(10); Rha(2)-C(10)-C(12:1); Rha(2)-C(12)-C(10); Rha(2)-C(10)-C(12)). The ratio of Rha(2)-C(10)-C(10) to Rha-C(10)-C(10) was higher than has been reported in previous studies. Our methodology allowed us to distinguish between the isomeric pairs Rha-C(10)-C(8)/Rha-C(8)-C(10), Rha-C(10)-C(12)/Rha-C(12)-C(10), Rha(2)-C(10)-C(8)/Rha(2)-C(8)-C(10) and Rha(2)-C(12)-C(10)/Rha(2)-C(10)-C(12). For each isomeric pair, the congener with the shorter chain adjacent to the sugar was always more abundant than the congener with longer chain.
Monteiro
Safi A
SA
Departamento de Química, Universidade Federal do Paraná, Cx.P. 19081, 81531-990 Curitiba, PR, Brazil.
Sassaki
Guilherme L
GL
de Souza
Lauro M
LM
Meira
Joel A
JA
de Araújo
Janete M
JM
Mitchell
David A
DA
Ramos
Luiz P
LP
Krieger
Nadia
N
D005227:Fatty Acids / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D008055:Lipids / Q000032:analysis; D008745:Methylation; D008823:Micelles; D015394:Molecular Structure; D009005:Monosaccharides / Q000032:analysis; D019906:Nuclear Magnetic Resonance, Biomolecular; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013501:Surface-Active Agents / Q000737:chemistry*
D005227:Fatty Acids; D008055:Lipids; D008823:Micelles; D009005:Monosaccharides; D013501:Surface-Active Agents