The α-amylase gene as a marker for gene cloning : direct screening of recombinant clones

We report the construction and use of a new system for the direct screening of recombinant clones after transformation. The system uses a Bacillus subtilis-Escherichia coli shuttle vector that carries the B. subtilis structural gene for α-amylase. Insertion of foreign DNA into this gene results in a loss of amylolytic activity in the host cells that can be assayed using a simple and inexpensive staining procedure.