摘要:
A method for heterologous cloning of a gene encoding α-amylase, protease, amyloglucosidase or glucose isomerase. The method involves the use of a bifunctional plasmid which can replicate in both E. coli and B. subtilis, and contains at least two selectable markers. A gene fragment for the enzyme is incorporated into the plasmid, leaving at least one functional selectable marker and a nonfunctional marker, producing a mixture of recombinant hybrid plasmids and the original bifunctional plasmid. This mixture is incorporated into E. coli microorganisms and transformants seiected. The transformants which contain the recombinant plasmid are identified, and plasmid DNA extracted. The plasmid DNA is used to transform Bacillus host microorganisms and transformants containing the recombinant plasmids are selected by means of the functional selectable marker.