Influence of Dissolved Oxygen on the Pseudomonas aeruginosa 6K-11 Rhamnolipid Production

Abstract

Rhamnolipids (RL) are biosurfactants produced mainly by Pseudomonas aeruginosa strains that have environmental and industrial applications. However, their industrial-scale production still faces the challenge of improving the efficiency and cost-effectiveness of the process. The aim of this work was to optimize the cultivation conditions to increase the RL production by using Response Surface Methodology with key parameters of the process, such as oxygen level, agitation, temperature, nutrients, and residual frying oil as a low-cost carbon source. The optimized parameters were 3.04 g/L of nitrogen, 0.5 vvm of aeration and 180 rpm of agitation, with which 52.2 g/L was obtained in 168 h. The critical micellar concentration (CMC) of this RL was 3.14 g/L, and the Oil Spreading assay confirmed the presence of surface-active compounds in the purified RL that generated an average halo area of 2746.7 ± 72.0 mm2, which represents an increase of 2063.41% ± 28.36% compared to the negative control. These advances could contribute to more sustainable, cost-effective RL production, promoting its application in bioremediation processes and other industries.