Maged S. Ahmad, Baraka A. AbdEl-Salam, Manal M. Yaser, Safaa S. Taha

Abstract

Four lactic acid bacteria (LAB) isolated from sweet were screened for extracellular protease production in submerged fermentation medium using the dairy waste (whey) as a substrate. Different fermentation parameters such as media pH, temperature, carbon source and nitrogen source were studied for maximum production of protease enzyme. Two isolated lactic acid bacteria (LAB) showed maximum proteolytic activity and were identified as Lactobacillus plantarum and Enterococcus faecium using Biolog system. The highest protease activity of L. plantarum was (8.72Unit/ml), the protein content was (4.13mg/ml) and specific activity was (2.11Unit/mg) at optimum pH- 5 and 30ºC, after 36 hrs of incubation period, fructose was used as carbon source, and yeast extract was used as nitrogen source, whereas in (10.2Unit/ml), the protein content was (4.8mg/ml) and the specific activity was (2.13Unit/mg) at optimum pH-5.5 and 45ºC after 36hrs of incubation period, sucrose was used as a carbon source, and yeast extract was used as a nitrogen source for Enterococcus faecium.Two protease enzymes were partially purified using ammonium sulphate precipitation followed by sephadex G-100 chromatography, and then they were characterized.