FIG. 2.

Restriction digestion analysis of amoA clones with MspI. Cloned amoA gene fragments were amplified from the cloning vector by using primers directed at the T7 and M13 reverse RNA polymerase binding sites, producing a fragment with approximately 70 bp of vector sequence on each end. The vector sequence contained no MspI recognition sites. Products were digested with a twofold excess of MspI for 1 h, analyzed by electrophoresis on a 2% agarose gel with TAE buffer, and visualized by ethidium bromide fluorescence. Lanes: 1, molecular size marker (100-bp ladder; Boehringer); 2, 9, and 19 pattern 1 amoA clones; 10, 17, and 18, pattern 2 amoA clones; 3 to 8, 11 to 16, and 20, pattern 3 amoA clones.