Quorum sensing (QS) has received significant attention in the past few decades. QS describes population density dependent cell to cell communication in bacteria using diffusible signal molecules. These signal molecules produced by bacterial cells, regulate various physiological processes important for social behavior and pathogenesis. One such process regulated by quorum sensing molecules is the production of a biosurfactant, rhamnolipid. Rhamnolipids are important microbially derived surface active agents produced by Pseudomonas spp. under the control of two interrelated quorum sensing systems; namely las and rhl. Rhamnolipids possess antibacterial, antifungal and antiviral properties. They are important in motility, cell to cell interactions, cellular differentiation and formation of water channels that Biotechnology and Genetic Engineering Reviews -Vol. 27, 159-184 (2010) Quorum sensing (QS) has received significant attention in the past few decades. QS describes population density dependent cell to cell communication in bacteria using diffusible signal molecules. These signal molecules produced by bacterial cells, regulate various physiological processes important for social behavior and pathogenesis. One such process regulated by quorum sensing molecules is the production of a biosurfactant, rhamnolipid Rhamnolipids are important microbially derived surface active agents produced by Pseudomonas spp. under the control of two interrelated quorum sensing systems; namely las and rhl Rhamnolipids possess antibacterial, antifungal and antiviral properties. They are important in motility, cell to cell interactions, cellular differentiation and formation of water channels that *To whom correspondence may be addressed (p.rahman@tees.ac.uk) Abbreviations: QS: quorum sensing; AI: autoinducer; HSL: homoserine lactone; AHL: acyl homoserine lactone; PQS: pseudomonas quinolone signal; sRNA: small ribonucleic acid; RL: rhamnolipid; HAA: 3-(3-hydroxyalkanoyloxy) alkanoic acid; CTAB: cetyl trimethyl ammonium bromide; TLC: thin layer chromatography; GC: gas chromatography; MS: mass spectroscopy; FTIR: fourier transform infrared spectroscopy; ATR: attenuated total reflectance; NMR: nuclear magnetic resonance; SDS: sodium dodecyl sulfate; CMC: critical micelle concentration; LPS: lipopolysaccharide; TMV: tobacco mosaic virus; PAT: pseudomonas autoinducer; FAD: flavin adenine dinucleotide; NAD: nicotinamide adenine dinucleotide; TDP: thiamine di-phosphate; mN/m-milli-Newton per meter 160 D.H. Dusane et al. are characteristics of Pseudomonas biofilms. Rhamnolipids have biotechnological applications in the uptake of hydrophobic substrates, bioremediation of contaminated soils and polluted waters. Rhamnolipid biosurfactants are biodegradable as compared to chemical surfactants and hence are more preferred in environmental applications. In this review, we examine the biochemical and genetic mechanism of rhamnolipid production by P. aeruginosa and propose the application of QS signal molecules in enhancing the rhamnoli...