The gene kerA (1,047 bp) encoding the main keratinase from Bacillus licheniformis was cloned into two conventional vectors, pET30 alpha and pET32 alpha, and expressed in Escherichia coli. From SDS-PAGE analysis, the recombinant keratinases were 45 and 55 kDa. They had different optimal pH values (7.5 and 8.5) but the same optimum temperature of 50 A degrees C. The recombinant keratinase produced in E. coli pET30 alpha-kerA was more stable than that produced in E. coli pET32 alpha-kerA, and retained approx. 70 % of its total enzyme activity after 30 min at 70 A degrees C.