In this study, we describe the production and properties of the bioemulsifier synthesized by Penicillium sp. grown in a medium supplemented with 300 mg L-1 of phenanthrene, where bioemulsifier production was not growth-associated. The maximum emulsifier production (2 +/- 0.3 g L-1) and emulsifying activity in cell-free culture medium (E-24 = 60 +/- 4%) were recorded on the 4th and 5th days, respectively. Of the various hydrocarbons tested, the best emulsifying activity was observed for kerosene, diesel, and xylene. The emulsifying agent maintained its properties over a wide range of pH (3-9), at high salinity (20% NaCl), and during exposure to elevated temperatures (93 degrees C). The fungal bioemulsifier was effective at these extreme environmental conditions and was able to emulsify the tested pure aromatic and aliphatic hydrocarbons and mixtures of the hydrocarbons. The bioemulsifier was composed by lipids (67%), carbohydrates (11%), and protein (7%). Myristic, stearic, and oleic were the major acids detected in the lipidic fraction. (c) 2006 Elsevier Ltd. All rights reserved.