Extracellular proteases from eight psychrotolerant antarctic strains

Extracellular proteases from 8 Antarctic psychrotolerant Pseudomonas sp. strains were purified and characterised. All of them are neutral metalloproteases, have an apparent molecular mass of 45 kDa, optimal activity at 40degreesC and pH 7-9, retaining significant activity at pH 5-11. With the exception of P96-18, which is less stable, all retain more than 50% activity after 3 h of incubation at pH 5-9 and show tow thermal stability (their half-life times range from 20 to 60 min at 40degreesC and less than 5 min at 50degreesC). These proteases can be used in commercial processes carried out at neutral pH and moderate temperatures, and are of special interest for their application in mixtures of enzymes where final thermal selective inactivation is needed. Results also highlight the relevance of Antarctic biotopes for the isolation of protease- producing enzymes active at tow temperatures. (C) 2004 Elsevier GmbH. All rights reserved.