Purification and characterization of an extracellular proline iminopeptidase from Corynebacterium variabilis NCDO 2101

Aims: To screen the extracellular proteolytic and lipolytic activities of C orynebacterium variabilis NCDO 2101 and to purify and characterize a prolin e iminopeptidase enzyme in order to investigate the role of the major compo nent of the smear of bacterial surface-ripened cheeses. Methods and Results: Four chromatographic steps were used to purify the enz yme and a three-factor, five-level Central Composite Design was used to stu dy the interactive effects of cheese-related values of pH, NaCl and tempera ture. The proline iminopeptidase showed some biochemical properties differe nt from the same enzyme purified from lactic acid bacteria and other smear bacteria. It tolerated NaCl concentrations up to 7.5% and was sensitive to low values of pH especially when they were combined with low temperature. Conclusions: The proline iminopeptidase of C. variabilis NCDO 2101 may have a role in proteolysis during ripening of smear surface-ripened cheeses. Significance and Impact of the Study: The findings of this work contribute to the knowledge of the enzymology of smear bacteria in order to improve th e ripening of bacterial surface-ripened cheeses.