Open AccessPhylogeny of Photorhabdus and Xenorhabdus based on universally conserved protein-coding sequences and implications for the taxonomy of these two genera. Proposal of new taxa: X. vietnamensis sp. nov., P. luminescens subsp. caribbeanensis subsp. nov., P. luminescens subsp. hainanensis subsp. nov., P. temperata subsp. khanii subsp. nov., P. temperata subsp. tasmaniensis subsp. nov., and the reclassification of P. luminescens subsp. thracensis as P. temperata subsp. thracensis comb. nov.
Author(s) -
Patrick Tailliez,
Christine Laroui,
Nadège Ginibre,
Armelle Paule,
Sylvie Pagès,
Noël Boemare
Publication year - 2010
Publication title -
international journal of systematic and evolutionary microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 173
eISSN - 1466-5034
pISSN - 1466-5026
DOI - 10.1099/ijs.0.014308-0
Subject(s) - biology , photorhabdus , photorhabdus luminescens , phylogenetic tree , subspecies , xenorhabdus , phylogenetics , microbiology and biotechnology , genetics , gene , zoology
We used the information from a set of concatenated sequences from four genes ( recA , gyrB , dnaN and gltX ) to investigate the phylogeny of the genera Photorhabdus and Xenorhabdus (entomopathogenic bacteria associated with nematodes of the genera Heterorhabditis and Steinernema , respectively). The robustness of the phylogenetic tree obtained by this multigene approach was significantly better than that of the tree obtained by a single gene approach. The comparison of the topologies of single gene phylogenetic trees highlighted discrepancies which have implications for the classification of strains and new isolates; in particular, we propose the transfer of Photorhabdus luminescens subsp. thracensis to Photorhabdus temperata subsp. thracensis comb. nov. (type strain CIP 108426 T =DSM 15199 T ). We found that, within the genus Xenorhabdus , strains or isolates that shared less than 97 % nucleotide identity (NI), calculated on the concatenated sequences of the four gene fragments ( recA , gyrB , dnaN and gltX ) encompassing 3395 nucleotides, did not belong to the same species. Thus, at the 97 % NI cutoff, we confirm the current 20 species of the genus Xenorhabdus and propose the description of a novel species, Xenorhabdus vietnamensis sp. nov. (type strain VN01 T = CIP 109945 T =DSM 22392 T ). Within each of the three current species of the genus Photorhabdus , P. asymbiotica , P. luminescens and P. temperata , strains or isolates which shared less than 97 % NI did not belong to the same subspecies. Comparisons of the four gene fragments plus the rplB gene fragment analysed separately led us to propose four novel subspecies: Photorhabdus luminescens subsp. caribbeanensis subsp. nov. (type strain HG29 T =CIP 109949 T =DSM 22391 T ), P. luminescens subsp. hainanensis subsp. nov. (type strain C8404 T = CIP 109946 T =DSM 22397 T ), P. temperata subsp. khanii subsp. nov. (type strain C1 T =NC19 T =CIP 109947 T =DSM 3369 T ), and P. temperata subsp. tasmaniensis subsp. nov. (type strain T327 T = CIP 109948 T =DSM 22387 T ).