Biosurfactant production by two isolates of Pseudomonas aeruginosa

Two strains of biosurfactant-producing bacteria, identified as Pseudomonas aeruginosa , were isolated from injection water and crude oil-associated water in Venezuelan oil fields. Both biosurfactants resembled rhamnolipids and produced stable emulsions of heavy and extra-heavy crude oils, reducing the surface tension of water from 72 to 28 dynes/cm. Tenso-active properties of the biosurfactants were not affected by pH, temperature, salinity or Ca super(2+) or Mg super(2+) at concentrations in excess of those found in many oil reservoirs in Venezuela.