Genome sequence of the versatile fish pathogen Edwardsiella tarda provides insights into its adaptation to broad host ranges and intracellular niches.
BACKGROUND
Edwardsiella tarda is the etiologic agent of edwardsiellosis, a devastating fish disease prevailing in worldwide aquaculture industries. Here we describe the complete genome of E. tarda, EIB202, a highly virulent and multi-drug resistant isolate in China.


RESULTS
E. tarda EIB202 possesses a single chromosome of 3,760,463 base pairs containing 3,486 predicted protein coding sequences, 8 ribosomal rRNA operons, and 95 tRNA genes, and a 43,703 bp conjugative plasmid harboring multi-drug resistant determinants and encoding type IV A secretion system components. We identified a full spectrum of genetic properties related to its genome plasticity such as repeated sequences, insertion sequences, phage-like proteins, integrases, recombinases and genomic islands. In addition, analysis also indicated that a substantial proportion of the E. tarda genome might be devoted to the growth and survival under diverse conditions including intracellular niches, with a large number of aerobic or anaerobic respiration-associated proteins, signal transduction proteins as well as proteins involved in various stress adaptations. A pool of genes for secretion systems, pili formation, nonfimbrial adhesions, invasions and hemagglutinins, chondroitinases, hemolysins, iron scavenging systems as well as the incomplete flagellar biogenesis might feature its surface structures and pathogenesis in a fish body.


CONCLUSIONS
Genomic analysis of the bacterium offered insights into the phylogeny, metabolism, drug-resistance, stress adaptation, and virulence characteristics of this versatile pathogen, which constitutes an important first step in understanding the pathogenesis of E. tarda to facilitate construction of a practical effective vaccine used for combating fish edwardsiellosis.
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China.
Qiyao
Q
Wang
Minjun
M
Yang
Jingfan
J
Xiao
Haizhen
H
Wu
Xin
X
Wang
Yuanzhi
Y
Lv
Lili
L
Xu
Huajun
H
Zheng
Shengyue
S
Wang
Guoping
G
Zhao
Qin
Q
Liu
Yuanxing
Y
Zhang
D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping / Q000379:methods; D020609:Edwardsiella tarda / Q000235:genetics* / Q000472:pathogenicity*; D005109:Extracellular Matrix / Q000378:metabolism; D005399:Fishes / Q000382:microbiology*; D005821:Genetic Techniques; D016680:Genome, Bacterial; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D010957:Plasmids / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction