Biosurfactant from Pseudomonas species with waxes as carbon source - Their production, modeling and properties

This study reports the production of biosurfactant from Pseudomonas aeruginosa and Pseudomonas fluorescens with waxes namely, n-hexadecane and n-eicosane as carbon sources. The latter organism produced 9.8 and 8.2 g L-1 of rhamnolipid containing C8 and C10 fatty acid with n-eicosane and n-hexadecane as substrates, respectively, whereas, the former produced 5.7 and 11.5 g L-1 of C10 and C12 fatty acids. Both the microorganisms were observed to degrade 85-90% of the waxes in one day and achieved very high cell surface hydrophobicity in a short period and indicates their ability of quick adherence to hydrophobic surfaces. The produced biosurfactant was stable upto 100 degrees C temperature, 8 MPa pressure, 20% (w/v) salinity and alkaline pH. Reaction kinetics was mathematically modeled using the Monod and Logistic growth model. The Logistic growth model was observed to fit the experimental values of biomass formed, biosurfactant produced, and the paraffins (waxes) degraded satisfactorily. The enhanced physico-chemical properties of biosurfactant with paraffin substrates, such as high bacterial adherence, wax degrading ability, emulsification activities, and surface tension reducing ability indicates the potential of these organisms in addressing oil spill, flow assurance and enhanced oil recovery process. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.