title: Characterization of rhamnolipid produced by Pseudomonas aeruginosa isolate Bs20.
abstract: Rhamnolipid produced by Pseudomonas aeruginosa isolate Bs20 is viscous sticky oily yellowish brown liquid with a fruity odor. It showed solubility at aqueous pH > 4 with optimum solubility at pH 7-7.5 and freely soluble in ethyl acetate. This biosurfactant has a very high surface activity as it could lower the surface tension of water to 30 mN/m at about 13.4 mg/L, and it exhibited excellent stabilities at high temperatures (heating at 100 degrees C for 1 h and autoclaving at 121 degrees C for 10 min), salinities (up to 6% NaCl), and pH values (up to pH 13). The produced biosurfactant can be used in the crude form either as cell-free or cell-containing culture broth of the grown bacteria, since both preparations showed high emulsification indices ranged between 59% and 66% against kerosene, diesel, and motor oil. These characters make the test rhamnolipid a potential candidate for use in bioremediation of hydrocarbon-contaminated sites or in the petroleum industry. High-performance thin-layer chromatography densitometry revealed that the extracted rhamnolipid contained the two most active rhamnolipid homologues dirhamno dilipidic rhamnolipid and monorhamno dilipidic rhamnolipid at 44% and 56%, respectively, as compared to 51% and 29.5%, respectively, in a standard rhamnolipid preparation. The nature and ratio of these two rhamnolipid homologues showed to be strain dependent rather than medium-component dependent.
authors.affiliation: Department of Microbiology and Immunology, Faculty of Pharmacy, Ain Shams University, Al Khalifa Al Maamoun St., Abbassia, Cairo, Egypt.
authors.forename: Ahmad Mohammad
authors.initials: AM
authors.lastname: Abdel-Mawgoud
authors.forename: Mohammad Mabrouk
authors.initials: MM
authors.lastname: Aboulwafa
authors.forename: Nadia Abdel-Haleem
authors.initials: NA
authors.lastname: Hassouna
mesh_terms: D002855:Chromatography, Thin Layer; D003460:Crystallization; D045703:Emulsifying Agents; D006017:Glycolipids / Q000032:analysis / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification* / Q000378:metabolism*; D054712:Salinity; D012996:Solutions; D013500:Surface Tension; D013696:Temperature
chemical_list: D045703:Emulsifying Agents; D006017:Glycolipids; D008823:Micelles; D012996:Solutions; C418382:rhamnolipid