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Title: Comparative genomics of Campylobacter iguaniorum to unravel genetic regions associated with reptilian hosts

Author
item GILBERT, MAARTEN - Utrecht University
item Miller, William - Bill
item Yee, Emma
item KIK, MARJA - Utrecht University
item ZOMER, ALDERT - Utrecht University
item WAGENAAR, JAAP - Utrecht University
item DUIM, BRIGITTA - Utrecht University

Submitted to: Genome Biology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2016
Publication Date: 9/6/2016
Citation: Gilbert, M., Miller, W.G., Yee, E., Kik, M., Zomer, A., Wagenaar, J., Duim, B. 2016. Comparative genomics of Campylobacter iguaniorum to unravel genetic regions associated with reptilian hosts. Genome Biology and Evolution. Genome Biol Evol. 2016 Oct 5;8(9):3022-3029.

Interpretive Summary: Campylobacter iguaniorum is related to, but distinct from, the agriculturally-relevant species C. fetus, and has recently been proposed as a novel Campylobacter species. Reptiles, lizards in particular, appear to be the primary reservoir of this Campylobacter species. Campylobacters are not often found in reptiles due to the low body temperature of these animals. The pathogenicity of this species is unknown: strains have been recovered both from reptiles with and without clinical signs of disease; however, strains of the related reptile-associated campylobacter Campylobacter fetus subsp. testudinum have been isolated from human clinical samples. To identify genetic features associated with the colonization of reptiles, the chromosomal sequences of two strains of C. iguaniorum were compared to those of two strains of a reptile-associated C. fetus subspecies. Potentially host-associated genes were identified: genes permitting growth at lower temperatures and genes that allow the use of nutrients that are often found in the reptilian intestinal tract.

Technical Abstract: Campylobacter iguaniorum is genetically related to the species C. fetus, C. hyointestinalis, and C. lanienae. Reptiles, chelonians and lizards in particular, appear to be the primary reservoir of this Campylobacter species. Here we report the genome comparison of C. iguaniorum strain 1485E, isolated from a bearded dragon (Pogona vitticeps), and strain 2463D, isolated from a green iguana (Iguana iguana), with the genomes of closely related taxa, in particular with reptile-associated C. fetus subsp. testudinum. The circular genome size of C. iguaniorum strain 1485E is 1.68 Mb and includes a 70.0 kb megaplasmid. Strain 2463D is 1.81 Mb with a 54.8 kb megaplasmid. C. iguaniorum shared highest homology with C. hyointestinalis and C. fetus. In contrast to C. fetus, C. iguaniorum does not encode an S-layer and is lacking a defined LOS region, bounded by waa genes and containing multiple glycosyltransferases. Instead, multiple predicted glycosylation regions were identified in C. iguaniorum. One of these regions is >50 kb with deviant G+C content, suggesting acquisition via lateral transfer. A similar syntopic, but non-homologous glycosylation region was identified in strain 2463D. Four large genomic islands and putative prophages were identified in strain 2463D, one containing an incomplete type IV secretion system. Multiple genes encoding respiratory enzymes not identified to date within the C. fetus clade were present. As in reptile-associated C. fetus subsp. testudinum, a putative tricarballylate catabolism locus was identified. This genomic study provides a better understanding of host adaptation, virulence, phylogeny, and evolution of C. iguaniorum and related Campylobacter taxa.