The properties and applications of rhamnolipid surfactants produced by Pseudomonas aeruginosa L2-1 from cassava wastewater added with waste cooking oil (CWO) as low-cost substrate, were investigated and compared with the commercial rhamnolipid mixture JBR599 (Jeneil Biosurfactant Co., Saukville, USA). The rhamnolipids produced by strain L2-1 were characterized by high performance liquid chromatography-mass spectrometry. Sixteen different rhamnolipid congeners were detected, with Rha-C(10)-C(10) and Rha-Rha-C(10)-C(10) being the most abundant. The L2-1 rhamnolipids from CWO showed similar or better tensioactive properties than those from JBR599, with a minimal surface tension of 30 mN/m and a critical micelle concentration (CMC) of 30 mg/l. The L2-1 biosurfactants formed stable emulsions with several hydrocarbons and showed excellent emulsification of soybean oil (100%). These rhamnolipids removed 69% of crude oil present in contaminated sand samples at the CMC and presented antimicrobial activity against Bacillus cereus (32 mu g/ml), Micrococcus luteus (32 mu g/ml) and Staphylococcus aureus (128 mu g/ml). These results demonstrate that the rhamnolipids produced in ONO can be useful for industrial applications, such as the bioremediation of oil spills. (C) 2010 Elsevier Ltd. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)