A biosurfactant-producing microorganism was isolated from activated sludge by enrichment culture when grown on a minimal salt medium containing n-hexadecane as a sole carbon source. This microorganism was identified as Pseudomonas sp. and it was named Pseudomonas sp. EL-G527. It's optimal culture condition is 2% n-hexadecane, 0.2% NH4NO3, 0.3% KH2PO4, 0.3% K2HPO4, 0.02% MgSO4ㆍ7H2O, 0.0025% CaCl2ㆍ6H2O, 0.0015% FeSO4ㆍ7H2O in 1ℓ distilled water and initial pH 7.0. Cultivation was initiated with a 2% inoculum obtained from starter cultures grown in 30 ㎖ of the same medium in 250 ㎖ flask. They were cultivated at 30 ℃ in reciprocal shaking incubator and the highest biosurfactant production was observed after 4 days.