Objective Lipases are often used in immobilized form, but commercial immobilized lipases are costly. An alternative is to produce lipases in solid-state fermentation, dry the solids and then use the "dry fermented solids" (DFS) directly. We produced DFS by growingBurkholderia contaminanson a mixture of sugarcane bagasse and sunflower seed meal and used the DFS to esterify oleic acid with ethanol in subcritical and supercritical CO(2)at 40 degrees C. Results Compared to a control without CO(2)at atmospheric pressure, subcritical CO(2)at 30 bar improved esterification activity 1.2-fold. Higher pressures, including supercritical pressures up to 150 bar, reduced activity to less than 80% of the control. At 30 bar, the esterification activity was improved a further 1.8-fold with the addition of 9% water (i.e. 9 g water per 100 g oleic acid) to the reaction medium. Conclusion A subcritical CO(2)atmosphere, with the addition of a small amount of water, improved the esterification activity of DFS containing lipases ofBurkholderia contaminans.