title: Delineation of two Helicobacter bilis genomospecies: implications for systematics and evolution.
abstract: The evolution and taxonomy of Helicobacter bilis strains isolated in Italy and Finland were studied by phylogenetic analysis of different genes, comparative analysis of small rRNA gene intervening sequence (IVS), amplified fragment length polymorphism analysis and DNA-DNA hybridization. The results of this study divided the H. bilis strains into two distinct and divergent genomic groups. In the absence of a specific phenotype or pathotype to distinguish these groups, however, they may be referred to as two genomospecies: H. bilis sensu stricto and Helicobacter sp. FL56. The phylogenetic network of gyrB and ureB gene sequences, as well as the comparative analysis of small rRNA gene IVS, suggests independent evolution of the two genomospecies. In particular, Helicobacter sp. FL56 seems to be the result of adaptation of an ancestral H. bilis strain in a new host. The phenomenon of adaptation to different hosts, or different intestinal niches in the same host, associated with high mutation and recombination rates could explain the evolution and the complex taxonomy of the genus Helicobacter. A comprehensive phylogenomics study of this genus would be useful to properly investigate this hypothesis.
authors: Department of Food and Environmental Hygiene, University of Helsinki, P.O. Box 66, Agnes Sjöbergin katu 2, FI-00014 Helsinki, Finland.
authors: Mirko
authors: M
authors: Rossi
authors: Department of Veterinary Public Health and Animal Pathology, Alma Mater Studiorum, University of Bologna, Via Tolara di Sopra 50, 40064 Ozzano Emilia, Bologna, Italy.
authors: Renato Giulio
authors: RG
authors: Zanoni
authors: Department of Food and Environmental Hygiene, University of Helsinki, P.O. Box 66, Agnes Sjöbergin katu 2, FI-00014 Helsinki, Finland.
authors: Marja-Liisa
authors: ML
authors: Hänninen
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D016172:DNA Fingerprinting; D027081:DNA Gyrase / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005387:Finland; D016998:Helicobacter / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D016481:Helicobacter Infections / Q000382:microbiology / Q000662:veterinary*; D007438:Introns / Q000235:genetics; D007558:Italy; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D014510:Urease / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D014510:Urease; D027081:DNA Gyrase