Isolation procedures for thermostable neutral proteinases produced by Bacillus stearothermophilus

Summary Purification procedures for extracting and concentrating thermostable neutral proteinases using vacuum evaporation and ammonium sulfate precipitation, or adsorption chromatography on amberlite XAD-7 resin were compared. Adsorption chromatography proved to be the most effective method to concentrate, extract and partially purify the thermostable neutral proteases produced by Bacillus stearothermophilus NCIB 8924 and NRRL B-3880. Proteases can also be extracted from large volumes of culture media containing only weak proteolytic activity and a low protein concentration. Final purification of the thermostable neutral proteases was performed with an established affinity chromatography method. The method seems to be suitable for scaling up.