Genetic differentiation among isolates of Teredinibacter  turnerae, a widely occurring intracellular endosymbiont  of shipworms.
Teredinibacter turnerae is a cultivable intracellular endosymbiont of xylotrophic (woodfeeding)bivalves of the Family Teredinidae (shipworms). Although T. turnerae has been isolated from many shipworm taxa collected in many locations, no systematic effort has been made to explore genetic diversity within this symbiont species across the taxonomic and geographical range of its hosts. The mode of symbiont transmission is unknown. Here, we examine sequence diversity in fragments of six genes (16S rRNA, gyrB, sseA, recA, rpoB and celAB) among 25 isolates of T. turnerae cultured from 13 shipworm species collected in 15 locations in the Atlantic, Pacific and Indian Oceans. While 16S rRNA sequences are nearly invariant between all examined isolates (maximum pairwise difference <0.26%), variation between examined protein-coding loci is greater (mean pairwise difference 2.2–5.9%). Phylogenetic analyses based on each protein-coding locus differentiate the 25 isolates into two distinct and well-supported clades. With five exceptions, clade assignments for each isolate were supported by analysis of alleles of each of the five protein-coding loci. These exceptions include (i) putative recombinant alleles of the celAB and gyrB loci in two isolates (PMS-535T.S.1b.3 and T8510), suggesting homologous recombination between members of the two clades; and (ii) evidence for a putative lateral gene transfer event affecting a second locus (recA) in three isolates (T8412, T8503 and T8513). These results demonstrate that T. turnerae isolates do not represent a homogeneous global population. Instead, they indicate the emergence of two lineages that, although distinct, likely experience some level of genetic exchange with each other and with other bacterial species.
Marine Science Institute, University of the Philippines-Diliman, Quezon City, 1101, Philippines.
Marvin A
MA
Altamia
Laboratory for Marine Genomic Research, Ocean Genome Legacy Inc., Ipswich, MA, 01938, USA.
Nicole
N
Wood
Laboratory for Marine Genomic Research, Ocean Genome Legacy Inc., Ipswich, MA, 01938, USA.
Jennifer M
JM
Fung
Laboratory for Marine Genomic Research, Ocean Genome Legacy Inc., Ipswich, MA, 01938, USA.
Sandra
S
Dedrick
Department of Biology, Central Michigan University, Mount Pleasant, MI, 48859, USA.
Eric W
EW
Linton
Marine Science Institute, University of the Philippines-Diliman, Quezon City, 1101, Philippines.
Gisela P
GP
Concepcion
Institute of Environmental Health, Oregon Health & Science University, Portland, OR, 97239, USA.
Margo G
MG
Haygood
Ocean Genome Legacy Center of New England Biolabs, Marine Science Center, Northeastern University, Nahant, MA, 01908, USA.
Daniel L
DL
Distel
D000818:Animals; D001267:Atlantic Ocean; D049872:Bivalvia / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D020563:Gammaproteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D014644:Genetic Variation; D019156:Indian Ocean; D010140:Pacific Ocean; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S