The invention relates to recombinant nucleic acid and polypeptides encodingcollagenase I andcollagenase II, methods for the preparation thereof and methods for the usethereof The presentinvention also provides a method for detecting the secretion of a hemolytictoxin by a bacterialproduction strain, wherein the production strain produces a collagenase, priorto therapeuticadministration of said collagenase to a patient and methods for detecting thepresence of a hemolytictoxin in a collagenase composition.