Shotgun optical maps of the whole Escherichia coli O157 : H7 genome

We have constructed Nhe1 and Xho1 optical maps of Escherichia coil O157:H7 solely from genomic DNA molecules to provide a uniquely valuable scaffold f or contig closure and sequence validation. E. coil O157:H7 is a common path ogen found in contaminated food and water. Our approach obviated the need f or the analysis of clones, PCR products, and hybridizations, because maps w ere constructed from ensembles of single DNA molecules. Shotgun sequencing of bacterial genomes remains labor-intensive, despite advances in sequencin g technology. This is partly due to manual intervention required during the last stages of finishing. The applicability of optical mapping to this pro blem was enhanced by advances in machine vision techniques that improved ma pping throughput and created a path to full automation of mapping. Comparis ons were made between maps and sequence data that characterized sequence ga ps and guided nascent assemblies.