Activity: Talk or presentation › Oral presentation
The commercial exploitation of rhamnolipid biosurfactants synthesised by Pseudomonas aeruginosa presents complications due to the pathogenicity of this bacterium. Therefore, a significant body of research has culminated in numerous papers reporting the identification of “novel” rhamnolipid synthesising bacteria. A critical evaluation of this of work has revealed that many of these studies utilised methodologies unreliable in definitively proving rhamnolipid synthesis. Some of these studies have also used outdated phenotypic or culture-driven microbiological methods of identifying the bacterial strains. Presented here are the methodologies we believe are rigorous in verifying rhamnolipid synthesis. These include sensitive analytical chemistry techniques for accurately characterising rhamnolipid congeners from a purified sample such as High-Performance Liquid Chromatography Mass Spectrometry (HPLC-MS) and/or Nuclear Magnetic Resonance (MNR) spectroscopy. Additionally, any bacterial strain shown to be synthesising rhamnolipids should be identified via the sequencing of phylogenetic reference genes (i.e. 16S rRNA). Finally, we suggest that screening of rhamnolipid synthesis genes should be attempted using in vitro or in silico techniques. This pipeline has been applied in our laboratory in the investigation of rhamnolipids synthesised by Burkholderia thailandensis and two marine bacterial strains which were not reported before to produce rhamnolipids; a Pseudomonas sp. MCTG214(3b1) and Marinobacter sp. MCTG107b.