Disentangling the Population Structure and Evolution of the Clam Pathogen Vibrio tapetis

Abstract

Vibrio tapetis is a fastidious slow-growing microorganism that causes the Brown Ring Disease in clams. Recently, two subspecies for this bacterial pathogen have been proposed. We have developed a multilocus sequence typing scheme and performed evolutionary studies of V. tapetis population using the great majority of isolates of V. tapetis obtained worldwide until now (30 isolates). V. tapetis constitutes a high polymorphic population, showing low diversity indexes and some genetic discontinuity among the isolates. Mutation events are more frequent than recombination, although both are approximately equally important for genetic diversification. In fact, the divergence between subspecies occurred exclusively by mutation but the diversity observed among isolates of the same subspecies appeared to be generated mostly by recombination. Between the subspecies, genetic distance is very high and almost no recurrent gene flow exists. This pathogen displays a non-clonal population structure with an ancient spatial segregation population and some degree of geographical isolation, followed by a population expansion, at least for V. tapetis subsp. tapetis. A database from this study was created and hosted on publmlst.org ( http://pubmlst.org/vtapetis/ ).

Bacterial diseases in marine bivalves

“…Interestingly the highest virulence recorded is still attributed to the first strain, CECT4600, isolated in Landéda in 1990 and contains a large conjugative plasmid pVT1 (Erauso et al, 2011). V. tapetis is highly polymorphic and displays a non-clonal population structure (Balboa et al, 2014).…”

From the Gene Sequence to the Phylogeography through the Population Structure: The Cases of Yersinia ruckeri and Vibrio tapetis

“…V. tapetis shows a non-clonal, panmictic population in where the two subspecies are generated by mutational events but the diversification within each of them is produced mostly by recombination [109].…”