The production of extracellular Hpase in submerged cultures of Yarrowia lipolytica CECT 1240 has been investigated. Several compounds have been added to the culture medium, in order to assess their efficiency as inducers of lipase production. First, the effect of triglycerides (olive oil, sunflower oil, tributyrin) and fatty acids (oleic acid) has been studied. The highest activity level was obtained with sunflower oil (58 U cm(-3)), followed by olive oil (49 U cm(-3)). The cultures with tributyrin and oleic acid attained similar activities (33 U cm(-3)). Then, several surfactants (Tween 80, Triton X-100, gum arabic, polyethylene glycol 200) were added to the cultures with sunflower oil, in an attempt to increase the levels of extracellular lipase activity. The obtained activities were slightly lower than those achieved without surfactants. The assay of a wide range of surfactant concentrations in the case of PEG-200 (with which the highest activity levels had been attained) did not improve the results. This strain secreted lipase concentrations two-fold higher and showed significantly different behaviour towards the presence of surfactants in the culture medium, compared with other wild-type Yarrowia lipolytica strains. (C) 2003 Society of Chemical Industry.