Genetic Diversity in Microcystis Populations of a French Storage Reservoir Assessed by Sequencing of the 16S-23S rRNA Intergenic Spacer

Abstract

We compared the genetic diversity of the 16S-23S spacer of the rRNA gene (ITS1) in benthic and pelagic colonies of the Microcystis genus isolated from two different sampling stations with different depths and at two different sampling times (winter and summer) in the French storage reservoir of Grangent. In all, 66 ITS1 sequences were found in the different clone libraries. The nucleotide diversity of all the sampled isolates were in the same range (average number = 0.022) regardless of their origin, showing that several clones are involved in the summer bloom event and contribute to the high biomass production. Phylogenetic study and analysis of molecular variance (AMOVA) revealed no obvious genetic differentiation between the benthic and pelagic isolates. This finding confirms that the Microcystis genus in this lake is characterized by having both a benthic phase in winter and spring allowing this organism to survive in unfavorable environmental conditions, and a pelagic phase in summer and autumn when environmental conditions allow them to grow in the water column. Finally, comparing these sequences with those available in the GenBank database showed that some highly conserved genotypes are found throughout the world.

Spatiotemporal changes in the genetic diversity of a bloom-forming Microcystis aeruginosa (cyanobacteria) population

“…Amplifications of the target region were checked by electrophoresis on a 1.5% agarose gel stained with ethidium bromide. In every sample, a single band was observed by electrophoresis, which is consistent with the fact that the ITS sequence is the same in the two rRNA operons present in Microcystis (Janse et al, 2003;Humbert et al, 2005).…”

Cytomorphological and Genetic Characterization of Troglobitic Leptolyngbya Strains Isolated from Roman Hypogea

“…These domains are important sites for folding of the rRNA transcripts or for the transcriptional antitermination and the encoding of tRNA Ile and tRNA Ala (32). High identity in the conserved domains and polymorphisms in the variable regions of the ITS were also found in benthic and pelagic Microcystis colonies from a French storage reservoir (29). Nonetheless, the more variable regions (V2, box B, and V3) facilitated the discrimination among the six strains, defining three clusters, one with the red strains, one with the two green isolates VRUC201 and VRUC206, and another one with the green strain VRUC184.…”

“…It has been recently proposed to divide the genus Leptolyngbya into at least two genera, each with six ecological groups, for easier identification, since the majority of the 91 species so far described have distinct and delimited ecological requirements (35). A polyphasic approach combining morphological, ultrastructural, molecular, and ecophysiological studies is the most progressive method in the modern taxonomic study of cyanobacteria (19,20,29,35,38,56). This approach is especially suitable for the taxonomy of species belonging to genera such as Leptolyngbya, which are morphologically very simple.…”

Genetic Diversity ofCylindrospermopsisStrains (Cyanobacteria) Isolated from Four Continents

“…Therefore, the ITS1 fragment is, so far, the only genetic marker providing robust phylogenetic inferences between Cylindrospermopsis strains. This marker was previously used to study subgeneric phylogenetic relationships in Microcystis (14,22), Arthrospira (1, 24), and Microcoleus (2). Our findings with ITS1 suggest that the recent invasion of Europe and of Central and North America by Cylindrospermopsis did not result from recent colonization events by African or Australian isolates as proposed by Padisák (23).…”