Characterization of rhamnolipids produced by non-pathogenic Acinetobacter and Enterobacter bacteria

• Published in: Bioresource technology 2013-02, Vol.130, p.510-516
• Main Authors: Hošková, Miriam, Schreiberová, Olga, Ježdík, Richard, Chudoba, Josef, Masák, Jan, Sigler, Karel, Řezanka, Tomáš
• Format: Article
• Language: English
• Subjects: Acinetobacter; Acinetobacter calcoaceticus; Acinetobacter calcoaceticus - metabolism; Bacteria; Biological and medical sciences; Enterobacter; Enterobacter - metabolism; Enterobacter asburiae; Fundamental and applied biological sciences. Psychology; Glycolipids - biosynthesis; Glycolipids - isolation & purification; Pseudomonas aeruginosa; Pseudomonas aeruginosa - metabolism; Rhamnolipids; Strain; Tandem Mass Spectrometry
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2012.12.085

[Display omitted] ► Rhamnolipids were produced by non-pathogenic bacteria E. asburiae and A. calcoaceticus. ► These rhamnolipids have mild impact on cell properties of soil bacteria. ► Growth media differing in carbon, nitrogen and phosphorus source were tested. ► Correlation of rhamnolipid fatty acid structure and its properties is indicated. Rhamnolipid production by two non-pathogenic bacterial strains Acinetobacter calcoaceticus and Enterobacter asburiae, and established rhamnolipid producer Pseudomonas aeruginosa was investigated. Rhamnolipids were separated from supernatant and further purified by thin-layer chromatography. Mass spectrometry with negative electrospray ionization revealed rhamnolipid homologues varying in chain length and unsaturation. Tandem mass spectrometry identified mono-rhamnolipid and di-rhamnolipid homologues containing one or two 3-hydroxy fatty acids. Several media differing in carbon (sunflower oil, glycerol and sodium citrate), nitrogen (ammonium ions, nitrate) and phosphorus (total content) source, respectively, were tested to obtain enhanced rhamnolipid production. The best production (0.56g/l) was obtained when nitrate was used as a nitrogen source. Both strains produced rhamnolipids that exhibited excellent emulsification activity with aromatic and aliphatic hydrocarbons and several plant oils. Unlike P. aeruginosa the two strains, i.e. Acinetobacter and Enterobacter, are not pathogenic to humans.