Fig. 2 Denaturing gradient gel electrophoresis gel of Bacteria 16S rDNA polymerase chain reaction products (Bases 968 to 1406 relative to the E. coli rRNA sequence) amplified from USA (Lanes 1–4) and Norwegian (Lanes 5–6) soil-DNA extracts. Gel gradient ranging from 30 to 55% denaturant. Lane 1, no-till corn field; Lane 2, no-till soybean field; Lane 3, plowed corn field; Lane 4, plowed soybean field; Lane 5, fallow field; Lane 6, pastureland