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

Abstract

To screen the extracellular proteolytic and lipolytic activities of Corynebacterium variabilis NCDO 2101 and to purify and characterize a proline iminopeptidase enzyme in order to investigate the role of the major component of the smear of bacterial surface-ripened cheeses. Four chromatographic steps were used to purify the enzyme and a three-factor, five-level Central Composite Design was used to study the interactive effects of cheese-related values of pH, NaCl and temperature. The proline iminopeptidase showed some biochemical properties different 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. The proline iminopeptidase of C. variabilis NCDO 2101 may have a role in proteolysis during ripening of smear surface-ripened cheeses. The findings of this work contribute to the knowledge of the enzymology of smear bacteria in order to improve the ripening of bacterial surface-ripened cheeses.