Properties of Acid Ureases from Lactobacillus and Streptococcus Strains

The acid ureases from 37 strains belonging to the genera Lactobacillus and Streptococcus were partially purified and characterized. The 37 acid ureases were classified into 6 different types according to their electrophoretic mobilities. The 6 different types of acid ureases, from 6 representative strains (4 species of Lactobacillus and 2 species of Streptococcus), were further characterized. The molecular sizes of the enzymes ranged from 140,000 for Streptococcus salivarius to 350,000 for Lactobacillus animalis. The isoelectric points were found to be 4.6 (Streptococcus mitior), 4.7 (Lactobacillus reuteri, Lactobacillus ruminis and Streptococcus salivarius) and 4.8 (Lactobacillus animalis and Lactobacillus fermentum). The optimum pHs ranged from 2.0 for Lactobacillus fermentum and Lactobacillus reuteri to 5.0 for Lactobacillus ruminis. The optimum temperatures ranged from 55°C for Lactobacillus animalis and Lactobacillus ruminis to 65°C for Lactobacillus fermentum, Lactobacillus reuteri and Streptococcus...