Abstract
Two bacterial strains 26.1 B (I) and 22.39 B (II) were isolated from soil as alkaline lipase producing microorganisms. Strain 26.1 B (I) was identified as Pseudomonas nitroreducens nov. var. thermotolerans, and strain 22.39 B (II) was identified as Ps. fragi. When they were cultivated aerobically in a 20-liter jar fermentor in medium containing 2.0% soybean meal, they secreted a large amount of alkaline lipases. The enzymes were recovered efficiently as precipitates by adjusting the pH of the culture fluids to 4.0 with HCl. The enzymatic characteristics included: optimum pH, 9.5 (I, II); stable pH range, 5_??_11 (I, II); optimum temperatures, 50°C (I) and 75_??_80°C (II); and more than 95% of the enzyme activity remained after incubated at 70°C for 20min (I, II). Lipase activities were inhibited remarkably in the presence of anionic surfactants (I, II) and bile salts (I, II).
