Phylogenetic and morphological analyses of Microcystis strains (Cyanophyta/Cyanobacteria) from a Spanish water reservoir
Sanchis, Daniel; Padilla, Carlos; Del Campo, Francisca F.; Quesada, Antonio; Sanz-Alférez, Soledad
An accurate identification and classification of Microcystis strains is gaining importance, among other reasons because many Microcystis strains produce hepatotoxins. Although morphological criteria allow distinguishing Microcystis morphospecies from field samples, the taxonomy of this genus has been questioned in the last few years, and different molecular approaches have been applied to clarify it.Here, eighteen strains of Microcystis, isolated from a Spanish drinking-water reservoir, were identified by morphological criteria, and characterised by using two molecular markers, the 16S rRNA-23S rRNA ITS and the cpcBA-IGS regions. Different phylogenetic trees have been built comparing the obtained sequences among them and with the sequences found in the databases. Both ITSs and IGSs seem to be equally valid to establish phylogenetic relationships among Microcystis strains, since they gave rise to similar cluster arrangement of the isolated strains. Besides, the clusters were concordant with morphological observations. Our data suggest a monophyletic identity of isolates assigned to M. novacekii and M. wesenbergii, and a close relationship between M. novacekii and M. aeruginosa, as they form an independent group when their ITS and IGS sequences were compared with the sequences deposited in the databases.