Bacterial isolates from waste water oil-contaminated soil sample were screened and evaluated for biosurfactant production in this study. Using culture –dependent technique, twenty two (22) bacterial isolates were recovered from eight (8) different sites. The dominant species were Bacillus and Pseudomonas; with an occurrence rate of 22.73% each. The isolates were subjected to conventional biosurfactant screening tests: qualitatively (drop collapse and microplate assay) and quantitatively (oil speading and emulsification activity). In all, Bacillus and Pseudomonas species were positive for all the tests and they had a clearing zone of 4mm each and an emulsification capacity of 51.61% and 53.13% respectively. This confirms their ability to produce biosurfactants that reduce interfacial and surface tension thereby leading to increase in solubility and emulsification of these oils.
Keywords: Biosurfactants, Index Emulsification Test, Surface tension, drop collapse, oil waste water
