Isolation and characterization of Bacillus sp. IMV B-7883 proteases

The representatives of Bacillus are some of the best protease producers studied so far since they exhibit broad substrate specificity, significant activity, stability, simple downstream purification, short period of fermentation and low cost. Earlier, we showed that Bacillus sp. IMV B-7883 strain synthesizes an extracellular proteases, which exhibit elastolytic and fibrinogenolytic activity. The aim of the work was to isolate and purify these enzymes from the culture liquid of the Bacillus sp. IMV B-7883 strain, as well as to study their properties. Isolation and purification of proteases was carried out by precipitation of the culture liquid with ammonium sulfate, gel permeation and ion exchange chromatography and rechromatography on Sepharose 6B. As a result, proteases with elastolytic and fibrinogenolytic activity with a molecular weight of 23 and 20 kDa respectively were isolated with elastase activity increased by 63.6 and fibrinogenolytic activity by 44.1 times. The enzyme with elastase activity had a pH-optimum of 7.0 and hydrolyzed only elastin, while the enzyme with fibrinogenolytic activity was an alkaline protease with a pH-optimum of 8.0 and in addition to fibrinogen, showed specificity for fibrin and, in trace amounts, for collagen. Keywords: Bacillus sp. IMV B-7883, elastase, fibrinogenase, pH optimum, substrate specificity