No abstract

The separation from fermentation medium of extracellular serine alkaline protease (SAP) enzyme produced by Bacillus licheniformis was investigated using a cross¯ow ultra®ltration system. SAP was separated from the high molecular weight neutral protease (NP) and amylase (AMY) enzymes and from the low molecular weight organic acids and amino acids in a cross¯ow ultra®ltration system with 30 000 Da and 10 000 Da MWCO polysulfone membranes, respectively. The effects of transmembrane pressure (TMP), recirculation velocity (v), and initial enzyme concentration (C E ) on the permeate¯ux, on the activities of SAP, NP and AMY enzymes, and on the recovery of SAP were investigated. High permeate¯ux was obtained at high recirculation velocity and TMP, but at low initial enzyme concentration. SAP enzyme recovery and activity measured in the system also showed alterations with hydrodynamic conditions. The best operation conditions for the separation of SAP from NP and AMY were TMP = 20 kPa, v = 0.50 ms À1 and C E = 0.28 gdm À3 . The separation of SAP from the organic and amino acids was best performed at TMP = 100 kPa, v =0.33ms À1 and C E = 0.40 gdm À3 .

Separation conditions for the serine alkali protease (SAP) enzyme from the neutral protease and amylase enzymes of Bacillus licheniformis cells were investigated in a crossflow ultrafiltration system by using 30 000 Da MWCO polysulphone membrane. The effects of initial enzyme concentration and recirculation velocity on the permeate flux, on the total resistance, and on the recovery yield of SAP in the permeate were investigated. High permeate flux was obtained at high recirculation velocity but at low initial enzyme concentration, where the SAP enzyme activity was best recovered at low velocity and enzyme concentration conditions.