Transformation of alkalophilic bacillus strains

Novel methods and novel alkalophilic Bacillus strains are provided for the production of polypeptides of interest, preferably serine proteases. Plasmid constructs comprising the serine protease gene are introduced into a compatible host, generally a Bacillus already overproducing serine protease. Preferred host cells are those from Bacillus novo sp. PB92 and the preferred serine protease gene also originates from Bacillus PB92. Integration and maintenance of the plasmid in the host cell chromosome can be achieved by including a temperature sensitive origin of replication in the plasmid construct and growing under selective conditions.