Rhamnolipids production in semi-submerged static-cultivation using agar cubes as solid substrate.

Surfactants are amphiphilic molecules with a worldwide billionaire market. Although chemical surfactants are the most available and commonly used, the microbiologically produced congeners have attracted attention due to their low toxicity, biodegradability, and high ecological acceptability. Among microbial surfactants rhamnolipids stand out, with high yields of production, excellent surface-active properties and great potential market. However, the application of these compounds is still limited mostly because of excessive production costs. This study presents a cost-effective process for rhamnolipids production by semi-submerged static-cultivation using agar cubes as substrate. A concentration of 50 g/L of rhamnolipids was reached in semi-submerged static-cultivation using agar cubes containing corn bran and soybean oil. Through this static process, besides avoiding foam, gradual release of nutrients provides a large increase in P. aeruginosa growth and consequently on rhamnolipids production.