Abstract
I describe a general and rapid procedure allowing the isolation of specialized λ transducing phages from a λ library by lysogenic complementation of defective mutants of Escherichia coli. As an example, the cloning of the E. coli fabE gene and of two other adjacent genetic determinants is presented. Subcloning and determination of its nucleotide sequence reveals that fabE codes for the biotin carboxyl carrier protein (BCCP), one of the three subunits of acetyl coenzyme A carboxylase.