Phospholipase D (PLD) plays a crucial role in the enzyme-mediated preparation of phosphatidylserine (PS). A new PLD constitutively secreted by Ochrobactrum sp. ASAG-PL1 is now reported for the first time. After purification, the MW of the enzyme was similar to 37 kDa by SDS-PAGE. Its activity was highest at 40 A degrees C and pH 7.0 and more than 90 % of the initial activity was maintained after 30 days at 4 A degrees C and pH 7.0. This enzyme may then be useful as a potential biocatalyst for PS production.