Biosurfactant Production in Aerobic and Anaerobic Conditions by Different Species of the Genus Pseudomonas

Abstract

In a time where surface active agents are capable of reducing the energy of the bonds between water molecules by interacting with them to reduce surface tension, it would be unwise not to be able to generate these in masses. Different Pseudomonas species were grown in MSP (minimal sulphate phosphate) media containing salts, glycerol and glucose. P. aeruginosa grown aerobically in the presence of glycerol as carbon source showed the highest emulsion percentage (81.48%), most significant decrease in surface tension (20 mN/m) and rhamnose production of 2.86 mg/mL. However, in anaerobic conditions there was no emulsion, rhamnolipid production or decrease in surface tension. The rhamnolipids were molecularly characterized using ESI-MS (electrospray ionization-mass spectrometry), P. aeruginosa CVCM 411 is able to produce mono-rhamnolipids and di-rhamnolipids, being rhamnolipid RhC10C12:1 the predominant monomer. The specific growth rate for isolates of P. aeruginosa and P. fluorescens in MSP are 0.6732 h-1 and 0.2181 h-1, respectively. In conclusion, the formation of rhamnolipids by P. aeruginosa is linked to its growth (depending on μ), and its ability to generate about 35% of the μmax, in the presence of glucose (carbon source) and glycerol (applied as pulses).