Rhamnolipids are naturally occurring biosurfactants with a wide range of potential commercial applications. As naturally derived products they present an ecological alternative to synthetic surfactants. The majority of described rhamnolipid productions are single strain Pseudomonas spp. cultivations. Here we report rhamnolipids producing bacteria Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa that were cultivated separately and as mixed populations. The ratio and composition of rhamnolipid congeners was determined by tandem mass spectrometry with negative electrospray ionization. Mono-rhamnolipid and di-rhamnolipid homologues containing one or two saturated or monounsaturated 3-hydroxy fatty acids were found in all strains. Physiochemical characterization of rhamnolipids was evaluated by the critical micelle concentration determination, the emulsification test, oil displacement test and phenanthrene solubilization. Critical micelle concentrations of rhamnolipids produced by both single strain and mixed cultures were found to be very low (10-63 mg/l) and to correspond with saturated/unsaturated fatty acid content of rhamnolipid homologues. The rhamnolipids produced by all strains effectively emulsified crude petroleum in comparison with synthetic surfactants Tween 80 and sodium dodecyl sulfate (SDS). Good performance of phenanthrene solubilization was exhibited by rhamnolipids from E. asburiae. The single strain and co-cultures cultivations were proposed as a possible way to produce rhamnolipid mixtures with a specific composition and different physiochemical properties, which could be exploited in bioremediation of various hydrophobic contaminants.

Institute of Chemical Technology Prague Department of Biotechnology Technická 5 166 28 Prague 6 Czech Republic

Institute of Chemical Technology Prague Department of Biotechnology Technická 5 166 28 Prague 6 Czech Republic; Institute of Microbiology Academy of Sciences of the Czech Republic Vídeňská 1083 142 20 Prague 4 Czech Republic

Institute of Chemical Technology Prague Department of Environmental Chemistry Technická 5 166 28 Prague 6 Czech Republic

Institute of Chemical Technology Prague Laboratory of Mass Spectrometry Technická 5 166 28 Prague 6 Czech Republic

References provided by Crossref.org

Production and Characterization of Rhamnolipids Produced by Pseudomonas aeruginosa DBM 3774: Response Surface Methodology Approach

Rhamnolipids as a Tool for Eradication of Trichosporon cutaneum Biofilm

Using Odd-Alkanes as a Carbon Source to Increase the Content of Nutritionally Important Fatty Acids in Candida krusei, Trichosporon cutaneum, and Yarrowia lipolytica

Aspergillus fumigatus DBM 4057 biofilm formation is inhibited by chitosan, in contrast to baicalein and rhamnolipid