Partial Purification and Characterization of Extracellular Protease from Pedicoccus acidilactici

Abstract

Microbial proteases have wide industrial applications and proteases of the lactic acid bacteria (LAB) have received special attention because of their importance in the food and dairy industry. Of all the LAB, the proteolytic system of the pediococci is the least studied. Therefore, this study was aimed at characterizing and purifying the protease produced by Pediococcus acidilactici grown in de Man, Rogosa and Sharpe (MRS) broth. Casein concentration of 2% (w/v) and 2.5 ml of the crude enzyme were optimal for the activity of the protease. The crude protease had temperature and pH optima of 28 oC and 4.0 respectively thus indicating that the enzyme is a mesophilic and acidic protease. Purification of the enzyme by gel filtration chromatography on Sephadex G75 following ammonium sulphate precipitation gave 2.26 fold increase in purification with specific activity of 46.13 units/mg protein while purification on Sephadex CM50 resulted in reduced purification fold (1.24 - 1.59) with specific activity ranging between 25.39 - 32.54 units/mg protein. The protease showed a characteristic band on SDS-PAGE and the molecular weight was estimated between 45 and 66 kDa. The potential applications of the protease are discussed.

Keywords: Protease, lactic acid bacteria, Pediococcus acidilactici, enzyme purification.