HIGH-LEVEL PRODUCTION OF RECOMBINANT GLUTAMIC ACID-SPECIFIC PROTEASE FROM BACILLUS-LICHENIFORMIS IN BACILLUS-SUBTILIS EXPRESSION SYSTEM

To obtain large quantities of glutamic acid-specific protease isolated originally from Bacillus licheniformis (BLase), an expression plasmid was constructed by inserting the BLase gene into a plasmid vector (pU B110) for Bacillus subtilis. B. subtilis strain ISW1214 harboring the resultant recombinant plasmid containing the coding and 5'-promoter an d 3'-terminator regions of BLase gene secreted approximately 0.25 g/l of BLase in a culture medium contained in a 90-l jar fermenter, corres ponding to nearly 10 times the natural production level and resulting in a stable large-scale production. The amount of BLase in the culture medium accounted for roughly 60% of the total extracellular proteins secreted from the recombinant strain, simplifying enzyme purification.