Reversed micellar extraction of an extracellular protease from Nocardiopsis sp. fermentation broth

Extraction of an extracellular alkaline protease from Nocardiopsis sp. fermentation broth using reversed micelles of sodium di(2-ethylhexyl) sulfosuccinate (AOT) in isooctane was performed with equal phase volume ratio. This work describes the effects of pH, ionic strength and surfactant concentration on the enzyme transfer process from the aqueous to the organic phase by direct contact (5 min) between the two phases. The best conditions for extraction (38.4% of protein content with about 83.5% of activity) were obtained using 200 mM AOT, at pH 4.0 with 50 mM KCl. For back extraction, sodium carbonate buffer, at pH 5.0 with 100 mM of KCl allowed for the best conditions (47.2% of protein content with about 14.0% of activity). The low protease activity yield of 11.69% obtained for the total process, extraction and back-extraction, suggests enzyme denaturation or its allocation near the AOT hydrophobic tail.