HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary data Corrigendum Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Tanabe, Y. Articles by Watanabe, M. M. Search for Related Content PubMed PubMed Citation Articles by Tanabe, Y. Articles by Watanabe, M. M. Agricola Articles by Tanabe, Y. Articles by Watanabe, M. M.

Multilocus sequence typing (MLST) reveals high genetic diversity and clonal population structure of the toxic cyanobacterium Microcystis aeruginosa

¹ Environmental Biology Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
² Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan

Correspondence
Makoto M. Watanabe
makoto{at}biol.tsukuba.ac.jp

Microcystis aeruginosa is one of the most prevalent bloom-forming cyanobacteria and has been the cause of increasing public health concern due to the production of hepatotoxins (microcystins). To investigate the genetic diversity, clonality and evolutionary genetic background with regard to the toxicity of M. aeruginosa, a multilocus sequence typing (MLST) scheme was developed, based on seven selected housekeeping loci (ftsZ, glnA, gltX, gyrB, pgi, recA and tpi). Analysis of a collection of 164 isolates from Japan and other countries identified 79 unique sequence types (STs), revealing a high level of genetic diversity (H=0.951). Although recombination between loci was indicated to be substantial by Shimodaira–Hasegawa (SH) tests, multilocus linkage disequilibrium analyses indicated that recombination between strains probably occurs at some frequency but not to the extent at which alleles are associated randomly, suggesting that the population structure of M. aeruginosa is clonal. Analysis of subsets of strains also indicated that the clonal population structure is maintained even in a local population. Phylogenetic analysis based on the concatenated sequences of seven MLST loci demonstrated that microcystin-producing genotypes are not monophyletic, providing further evidence for the gain and loss of toxicity during the intraspecific diversification of M. aeruginosa. However, toxic strains are genetically distinct from non-toxic strains in MLST allelic profiles, and it was also shown that non-toxic strains harbouring toxin genes fall into a single monophyletic clade, except for one case. These results suggest that the toxicity of M. aeruginosa is relatively stable in the short term, and therefore can be unequivocally characterized by MLST. The MLST scheme established here will be of great help for future detailed population genetic studies of M. aeruginosa.

The GenBank/EMBL/DDBJ accession numbers for the ftsZ, glnA, gltX, gyrB, pgi, recA and tpi sequences of the Microcystis aeruginosa strains examined in this study are AB324850–AB325402.

A supplementary figure showing the individual phylogenetic trees for the seven MLST loci, and supplementary tables showing strain information and the degenerate primer sequences used for isolating five of the seven MLST genes, are available with the online version of this paper.

This article has been cited by other articles:

				G. Christiansen, C. Molitor, B. Philmus, and R. Kurmayer Nontoxic Strains of Cyanobacteria Are the Result of Major Gene Deletion Events Induced by a Transposable Element Mol. Biol. Evol., August 1, 2008; 25(8): 1695 - 1704. [Abstract] [Full Text] [PDF]

				T. Kaneko, N. Nakajima, S. Okamoto, I. Suzuki, Y. Tanabe, M. Tamaoki, Y. Nakamura, F. Kasai, A. Watanabe, K. Kawashima, et al. Complete Genomic Structure of the Bloom-forming Toxic Cyanobacterium Microcystis aeruginosa NIES-843 DNA Res, January 11, 2008; (2008) dsm026v1. [Abstract] [Full Text] [PDF]