Structural Elucidation and Surfactant Properties of Rhamnolipids Synthesized by Pseudomonas aeruginosa (ATCC 10145) on Sweet Water as Carbon Source and Stabilization Effect on Foam Produced by Sodium Lauryl Sulfate

Abstract

Abstract The interest in biosurfactant has increased considerably due to their large potential for industrial applications. Rhamnolipid is the simplest class of biosurfactants with well defined structure. The main obstacle in commercialization of biosurfactant especially rhamnolipids is the higher cost of the production that can be reduced by use of inexpensive carbon substrates like glycerol that is readily available from commercial fat-splitting process in the form of sweet water (up to 20% w/v) at very low cost. The composition and structure of various components in crude rhamnolipids synthesized by of Pseudomonas aeruginosa (ATCC 10145) on sweet water, were determined using TLC, HPLC and LC\MS. The crude product showed two distinct components having structure Rha2C10C10 and Rha2C10C12 at 85.45 wt.% and 14.55 wt.% respectively. The Rha2C10C10 was more efficient and effective in surface tension reduction up to 23.5 mN/m than other components. Crude rhamnolipids showed better emulsifying power than its individual components. The crude rhamnolipids showed better foam stability than sodium lauryl sulfate (SLS) at lower concentrations (0.05 to 0.002% w/v). It also enhanced and stabilized the foam produced by SLS at 0.01 to 0.025% of rhamnolipids.