Abstract: The invention relates to recombinant DNA molecules and to methods for producing proteins by means of said molecules. Particularly, the present invention relates to recombinant DNA molecules which are synthetized in Bacillus strain bacteria and are characterized by DNA which codes for exoenzymes excreted by a bacterium of the Bacillus strain and which are present in tens of copies in Bacillus strain bacteria, as well as to recombinant DNA molecules which are modified from the above recombinant DNA molecules and are characterized by DNA containing the regulation and excretion signals of the .alpha.-amylase gene of B. amyloliquefaciens, to which signals a gene of any protein can be joined. These recombinant DNA molecules can be used, for example, to improve the production of .alpha.-amylase in Bacillus strain bacteria, and their modifications to produce any protein in Bacillus strain bacteria.

Abstract: A selected protein or protein part is prepared in Bacillus strain bacteria by joining DNA encoding the selected protein or protein part essential to its biological activity to a bacterium gene. The Bacillus amyloliquefaciens gene for .alpha.-amylase is cleaved at a location after the excretion signal following the regulation sequence, or at a location after a part essential with respect to its excretion. The cleaved gene is joined to a plasmid present in Bacillus strain bacteria in several copies, and the DNA sequence encoding the selected protein or protein part essential to its biological activity is joined to the cleavage site by recombinant DNA techniques. Bacillus strain host bacteria are transformed with the recombinant DNA molecules so obtained, and the transformed host bacteria cultivated to produce the selected protein or protein part.