Milk clotting and proteolytic activity of enzyme preparation from Pediococcus acidilactici SH for dairy products

Abstract

Some microorganisms have the ability to produce enzymes that could clot milk and used as a substitute for calf rennet. Strains of lactic acid bacteria (LAB) could produce proteolytic enzymes that may have the potential to be used as a source of milk clotting enzyme (MCE). In the present study, LAB isolated from shrimp paste identified as Pediococcus acidilactici SH, was evaluated for milk clotting activity (MCA), proteolytic activity (PA) and enzyme production using different sources of nitrogen. Casein, tryptophan, trypticase peptone and tryptone soya were added to the enzyme production media, and casein was found to increase the MCA to 75.0 SU ml^-1 at pH 6.0 at 50°C. SDS-PAGE of the partially purified enzyme solution produced a band with a molecular weight of approximately 29 kDa. This study indicates the possibility of exploiting LAB from food sources for the production of MCEs for dairy production.

Keywords: Lactic acid bacteria (LAB), milk clotting activity, nitrogen source, Pediococcus acidilactici.

Abbreviation: MCE, Milk clotting enzyme; LAB, lactic acid bacteria; PA, proteolytic activity.