DNA Electrophoresis on Agarose Gels

DNA Electrophoresis on agarose gels was as previously described [26 (link),45 (link)], in which 1 to 1.5% agarose was used in 1 X Tris-acetate- EDTA buffer (1X TAE). We added equal volumes of bacterial supernatants to the wells in each gel experiment, usually 25 µL of the sample mixed with 10 X loading dye. Fluorescent DNA bands on gels were visualized using SybrSafe dye and photographed using the Gel Doc EZ instrument (Bio-Rad, Hercules, CA, USA) and the Image 5 software. Quantitation of gel bands and gel lanes was performed using the Un-Scan-It Gel program for the MacIntosh by Silk Scientific (Orem, UT, USA).