A rapid and complete 4-step protocol for obtaining nucleotide sequence from E. coli genomic DNA from overnight cultures.

We describe a rapid and complete 4-step protocol for obtaining DNA sequence from E. coli genomic DNA starting from overnight cultures. These steps are as follows: isolation and purification of genomic DNA; PCR amplification of the desired region; purification of the amplified DNA product; and finally, direct sequencing using the dideoxy chain termination procedure with simple modifications to improve signal intensity. Clean DNA sequence can be obtained from a large number of strains in a matter of days, using easily available kit-type reagents. This protocol should be generally applicable to genomic DNA from other species.