The AmpC beta -lactamase gene and a small portion of the regulatory ampR se
quence of Enterobacter aerogenes 97B were cloned and sequenced. The beta -l
actamase had an isoelectric point of 8 and conferred cephalosporin and ceph
amycin resistance on the host. The sequence of the cloned gene is most clos
ely related to those of the ampC genes of E. cloacae and C. freundii.