FIG. 1.

Design of primers INT/5CS and INT/3CS used in the ICA-PCR methodology to target amplification of the cassette arrays inserted into class 1 integrons and of primer ATT/SEQ used for direct sequencing of the attI site and downstream region of the amplification products. To facilitate cloning of the amplicons, an XbaI site (underlined) was engineered near the 5′ end of the amplification primers by introducing a point mutation in each of them (indicated by lowercase letters). Gene cassettes are represented by black arrows (coding sequences) followed by empty circles (59-base elements).