FIG 1.

Construction of integrons 1S and 2S. Integrons 1S and 2S were obtained by assembly PCR. To construct integron 1S, fragment B+C (2.2 kb) was first obtained and then coupled with fragment A. To construct integron 2S, fragments D and E were fused. Integron 1S was 3.9 kb, and integron 2S 1.9 kb. The primers used for assembly are represented by dotted lines and indicated by numbers (see Table 1S in the supplemental material), and the primers used for catB9 detection are represented by black arrows (Fwd is located in pSU38ΔtotlacZ).