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°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% H2 O2.