Draft genome sequence of non-shiga toxin-producing Escherichia coli O157 NCCP15738

Background: The non-shiga toxin-producing Escherichia coli (non-STEC) O157 is a pathogenic strain that cause diarrhea but does not cause hemolytic-uremic syndrome, or hemorrhagic colitis. Here, we present the 5-Mb draft genome sequence of non-STEC O157 NCCP15738, which was isolated from the feces of a Korean patient with diarrhea, and describe its features and the structural basis for its genome evolution.

Results: A total of 565-Mbp paired-end reads were generated using the Illumina-HiSeq 2000 platform. The reads were assembled into 135 scaffolds throughout the de novo assembly. The assembled genome size of NCCP15738 was 5,005,278 bp with an N50 value of 142,450 bp and 50.65 % G+C content. Using Rapid Annotation using Subsystem Technology analysis, we predicted 4780 ORFs and 31 RNA genes. The evolutionary tree was inferred from multiple sequence alignment of 45 E. coli species. The most closely related neighbor of NCCP15738 indicated by whole-genome phylogeny was E. coli UMNK88, but that indicated by multilocus sequence analysis was E. coli DH1(ME8569).

Conclusions: A comparison between the NCCP15738 genome and those of reference strains, E. coli K-12 substr. MG1655 and EHEC O157:H7 EDL933 by bioinformatics analyses revealed unique genes in NCCP15738 associated with lysis protein S, two-component signal transduction system, conjugation, the flagellum, nucleotide-binding proteins, and metal-ion binding proteins. Notably, NCCP15738 has a dual flagella system like that in Vibrio parahaemolyticus, Aeromonas spp., and Rhodospirillum centenum. The draft genome sequence and the results of bioinformatics analysis of NCCP15738 provide the basis for understanding the genomic evolution of this strain.