Production of a rhamnolipid-type biosurfactant by <i>Pseudomonas aeruginosa</I> LBM10 grown on glycerol

Abstract

The work herewith investigated the effect of the culture medium composition on rhamnolipid production by Pseudomonas aeruginosa LBM10, previously isolated from an estuarine environment in Southern Brazil. Experimental design and surface response methodology were used in order to improve biosurfactant production using glycerol, a renewable carbon source. The assays were carried out in a rotary shaker at 30°C and 180 rpm for 120 h and the parameters studied were glycerol concentration, C/N (carbon/nitrogen) and C/P (carbon/phosphorus) ratios. Low glycerol concentration and a phosphorus-limiting condition were favorable for rhamnolipid production. Contour plots constructed by predictive polynomial equations led to a glycerol concentration of 13.2 g/l, a C/N ratio of 12.8 and a C/P ratio of 40 in order to maximize rhamnolipid concentration (4.15 g/l) associated with a high emulsification index (61%).

Keywords: Biosurfactant, surface-active compounds, experimental design, phosphorus limitation