Purification and characterization of extracellular proteinases excreted by a strain of Bacillus subtilis BS2, isolated from fermented African locust bean 'iru'

Proteinases were excreted by strains of Bacillus subtilis during fermentation of African locust bean cotyledons. Those excreted by one strain were purified and characterized by ammonium sulphate precipitation, ion-exchange chromatography (IEC), gel filtration, inhibition tests and polyacrylamide gel electrophoresis (PAGE). Three proteinases and an esterase without proteolytic activity were identified. A serine proteinase which showed a high degree of hydrophobicity and a neutral proteinase were present. The third proteinase showed both proteolytic and esterolytic activities, and had multiple electrophoretic mobilities on polyacrylamide gel.