BACKGROUND: beta-Poly (L-malic acid) (PMLA) can be used as a pro-drug or for a drug-delivery system, while the separation of PMLA producer cells of Aureobasidium pullulans from its fermentation broth is a challenge. This paper reports the separation of A. pullulans from PMLA fermentation broth by membranes technology. RESULTS: The best separation efficiency was obtained by the membrane with a molecular weight cut off of 300 kDa, an initial feed volume of 1300 mL, a volume reduction ratio (VRR) of 7.2, a cross-flow velocity of 6ms(-1), a trans-membrane pressure (TMP) of 0.2MPa, and a temperature of 40 degrees C. The average flux reached 55.97 Lm(-2) h(-1) with a VRR of 7.2. The main foulingmechanism during the filtration of cell suspension solution was cake layer formation, while it was pore blocking for fermentation broth and cell free broth. Since the cake layer induced by cells would reject some macromolecular substances (i.e. reduce the pore blocking and enhance the fluxes), one step separation of A. pullulans with a 300 kDa membrane was better than that with centrifugation followed by membrane filtration. CONCLUSION: One step separation of A. pullulans by membranes technology would be beneficial for PMLA bio-refinery. (C) 2016 Society of Chemical Industry