P28: Rhamnolipids production by Pseudomonas aeruginosa LBI mutant

Biosurfactants have several advantages such as low toxicity, biodegradability and high stability, but they are not widely used because of the high cost of production. Therefore the aim of present study is optimize rhamnolipids production, using Pseudomonas aeruginosa LBI mutant to carry out bioreactor experiments. The microrganisms used were the mutant P. aeruginosa LBI 2A1 and the wild strain. The experiments were conducted in 2.5 L bioreactor (Minifors - Infors HT - Switzerland) with a nominal capacity of 0.7 L. For rhamnolipid production was used calcium-free mineral medium supplemented with sunflower oil and sodium nitrate as carbon and nitrogen source, respectively. Physicochemical parameters were: aeration - 0.4 L / min, temperature - 37 °C, pH - 6.8 ± 0.1, the stirring speed increased from 400 to 1100 rpm adjusted to maintain pO₂ above 10%, the volume of foam formed was controlled by antifoam Contraspum A4050. Maximum biomass were 12.2 g/L to the unmodified bacterium and 10.4 g/L to P. aeruginosa LBI 2A1. An increase of 70% in rhamnolipid production was observed for mutant compared to the wild type. The maximum concentrations achieved were 19.5 and 33.1 g / L, for the control and modified strain, respectively.