[Urease biosynthesis and isolation in Staphylococcus saprophyticus L-1].

Experiments were carried out to investigate the effect of organic components of the medium and cultivation conditions on the multiplication rate and urease biosynthesis by Staphylococcus saprophyticus L-1 cells isolated from natural sources. The yeast enzymic hydrolyzate and corn extract were found to be an adequate substitute for the costly organic components--peptone and yeast extract. The substitutes ensured a high level of urease biosynthesis and biomass accumulation. The biomass accumulation was maximum at pH 6.0-7.0 and the urease activity reached maximum at pH 6.0-6.5. The optimum temperature of cultivation was 37 degrees C. Enhanced aeration and constant pH during microbial cultivation in 250 1 fermenters did not increase the biomass accumulation or urease biosynthesis as compared to flask cultivation. The study of urease isolation from the cell extract showed that the ratio of 3 volumes of ethanol to 1 volume of homogenate was optimum and provided the best precipitation of the enzyme. Preliminary thermal treatment of the cell extract increased the urease activity by 2.5 times. In this situation the activity yield was close to 100%.