Screening for Cold-active Protease-producing Bacteria from the Culture Collection of Polar Microorganisms and Protease Characterization

Abstract

KOPRI has assembled a culture collection of cold-adapted bacteria from the Arctic and Antarctic. To identify excellent protease-producers among the proteolytic bacterial collection (874 strains), 78 strains were selected according to their relative activities and were subsequently re-examined for their extracellular protease activity on ZoBell/skim milk plates. This screening method permitted the selection of a small group of 15 cold-adapted bacteria, belonging to the genus Pseudoalteromonas or Flavobacterium, that showed proteolytic activities at 5&#8211

15°C. The cold-active proteases from these strains were classified into four categories according to the extent of enzymatic inhibition by a class-specific protease inhibitor. Since highly active and cold-adapted proteases have the potential for commercial enzyme development, the bacteria selected in this work are studied as a valuable natural source of new proteases. At present, a protease from one strain (KOPRI 21717), which is highly active at low temperatures and resistant to protein-denaturing SDS, is being studied for future application in detergent.