Production in sea-water of thermostable alkaline proteases by a halotolerant strain of Bacillus licheniformis

A halotolerant strain of Bacillus licheniformis, previously isolated from marine sediments, produced high protease activity during the early stationary phase of growth. The use of sea-water in the fermentation medium enhanced the production of this activity of 150%. After a partial purification, three different proteolytic enzymes could be detected, which were alkaline serine proteases, exhibiting optimal activity at pH 9.0 and at 70 degrees C. The proteases were activated by NaCl, with a two, three-fold increase in activity and were stable in presence of 0.7% NaBO3, 0.5% NaClO and 3% H2O2.