Rhamnolipids production by Pseudomonas aeruginosa LBI 2A1 using batch and feed batch cultivation

Biosurfactant are biological molecules that have regions of different polarity. The biological surfactants have several advantages over the synthetic, such as low toxicity, biodegradability and high stability. This study evaluates different cultivation types for rhamnolipids   production: batch, pulse feed batch and continuous feed batch. The cultivations was done in bioreactor using Pseudomonas aeruginosa LBI 2A1. The volume of aqueous phase was 4.0 L and 250 g / L of soybean oil. The pulse feed batch, started after 58h and was added 23,85g/L of soybean oil. The continuous feed batch started with 60h and was finished after 8h of feeding, the flow was 0.096 ml/min.The parameters were: aeration – 2.0 L / min, temperature - 37 °C, pH - 6.8 ± 0.1, the stirring speed 300 and 900 rpm; the foam was controlled by antifoam Contraspum A4050. Microbial growth was quantified by dry mass, rhamnolipids were quantified by HPLC, gravimetry was used to quantify the carbon source by. In the batch culture the maximum biomass was 12.4 g / L, and the rhamnolipids concentration was 36.4 g / L. On the pulse feed  batch the biomass reached 14.4 g / L, but the rhamnolipids production was 11.46 g / L. In continuous feed batch the microbial growth reached 13.75g/L after 62h of cultivation and the maximum product concentration was 22.5 g / L. In this work the best productions was reached in the batch process.