Genome Sequence of Escherichia coli Strain LCT-EC52, Which Acquired Changes in Antibiotic Resistance Properties after the Shenzhou-VIII Mission

There are many species of bacteria found in the human body, most of which are normal flora. Escherichia coli is a Gramnegative rod-shaped bacterium that commonly resides in the lower intestines of humans and mammals. When the immune system is compromised, E. coli can cause various diseases, including bacteremia, septicemia, meningitis, urinary tract infection, cholecystitis, cholangitis, dysentery, and pneumonia. It is reportedthatspaceflightmightdecreasehostimmunity,whichmay increasetheriskofcontractinginfectiousdiseasesrelatedtoE.coli strains that are harbored in the human body during space travel (1, 2). Thus, it is necessary to investigate the effect of space travel on E. coli. The E. coli strain CGMCC 1.2385 was loaded on the Shenzhou-VIII spacecraft, which traveled into space for 17 days. E. coli strain LCT-EC52 was isolated and showed significantly increased resistance to ampicillin, cefazolin, ceftazidime, ceftriaxone, and azithromycin (3). The nucleotides were fragmented to generate 500-bp and 6-kb fragment libraries. PCR was performed to amplify these 500-bp and 6-kb libraries for ~100 and ~50 genomic coverage, respectively. We performed paired-end sequencing of the libraries using an Illumina HiSeq 2000 according to the manufacturer’s instructions. Using SOAPdenovo (version 1.6), 90-bp reads from the two libraries were assembled into 191 contigs according to methods published previously and were connected to 37 scaffolds using information from paired-end sequencing of the 6-kb library. The total assembled nucleotide count is 5,209,752 bp, including 106,472 bp of unknown bases (gaps). The N50 of the assembled scaffolds is 2,676,640 bp, and the GC content is 50.37%. To predict coding sequences in the scaffolds, we used Glimmerversion3.0topredictputativeopenreadingframes.The resulting coding sequences (CDSs) were aligned to the NR, COG, and KEGG databases. We identified tandem repeat sequences us