A novel method for the detection of protease and the development of extracellular protease in early growth stages of Lactobacillus delbrueckii ssp. bulgaricus

A novel method of rapid detection using microplate wells with casein and ca lcium ions was developed for measuring protease activity. This new method i s based on the theory that the hydrolysis by the proteases reduces the turb idity of the solution without coagulation. The three Lactobacillus delbruec kii ssp. bulgaricus strains that were tested secreted a protease with activ ity that reached its maximum 4 to 8 h after incubation (log phase) and then decreased rapidly. The new method allows the protease activity to be detec ted and measured more rapidly, easily, and economically than do other metho ds with fluorescent reagents or radioisotopes, and the new method is especi ally useful for analyzing large numbers of test samples (e.g., chromatograp hically fractionated eluates).