Amino acid sequence of the blaZ gene in the transformant. The blaZ gene in the transformants K744-T and K2480-T as well as that of the donor plasmid pN315 was amplified by PCR using the primer pairs listed in Table 2. The nucleotide sequence was determined by the dideoxy chain termination method at Nippon Gene Research Laboratories (Miyagi, Japan). The nucleotide sequence was aligned by the computer programme, DNASIS Pro (Hitachi Software Engineering Co., Ltd., Tokyo, Japan), and was converted to the amino acid sequence. Amino acids are expressed by a single letter code. X mark denotes the amino acid residue, which could not be specified in this study. – denotes the amino acid residue, which is identical to that of pN315.