Phenotypic and genetic diversification of Pseudanabaena spp. (cyanobacteria)

Abstract

Pseudanabaena species are poorly known filamentous bloom-forming cyanobacteria closely related to Limnothrix. We isolated 28 Pseudanabaena strains from the Baltic Sea (BS) and the Albufera de Valencia (AV; Spain). By combining phenotypic and genotypic approaches, the phylogeny, diversity and evolutionary diversification of these isolates were explored. Analysis of the in vivo absorption spectra of the Pseudanabaena strains revealed two coexisting pigmentation phenotypes: (i) phycocyanin-rich (PC-rich) strains and (ii) strains containing both PC and phycoerythrin (PE). Strains of the latter phenotype were all capable of complementary chromatic adaptation (CCA). About 65 kb of the Pseudanabaena genomes were sequenced through a multilocus sequencing approach including the sequencing of the16 and 23S rRNA genes, the ribosomal intergenic spacer (IGS), internal transcribed spacer 1 (ITS-1), the cpcBA operon encoding PC and the IGS between cpcA and cpcB. In addition, the presence of nifH, one of the structural genes of nitrogenase, was investigated. Sequence analysis of ITS and cpcBA-IGS allowed the differentiation between Pseudanabaena isolates exhibiting high levels of microdiversity. This multilocus sequencing approach revealed specific clusters for the BS, the AV and a mixed cluster with strains from both ecosystems. The latter comprised exclusively CCA phenotypes. The phylogenies of the 16 and 23S rRNA genes are consistent, but analysis of other loci indicated the loss of substructure, suggesting that the recombination between these loci has occurred. Our preliminary results on population genetic analyses of the PC genes suggest an evolutionary diversification of Pseudanabaena through purifying selection.

Novel Clostridium populations involved in the anaerobic degradation of Microcystis blooms

“…We speculate that the divergence of niches, such as substance utilization and adaptation to environmental conditions (Macalady et al, 2008), could allow for this situation. Generally, genotypic diversification (Schauer et al, 2005) and even only phenotypic diversification (Acinas et al, 2009) can lead to bacterial niche divergence. Our phylogenetic analysis showed that genetic polymorphisms were evident among the Clostridium sequences, in which eight new clusters and subclusters (CLOS.1-8) and 18 singletons could be identified.…”

Mapping phytoplankton blooms in deep subalpine lakes from Sentinel-2A and Landsat-8

“…In the central part of the Lake Maggiore, two specimens revealed the presence of several cyanobacteria mostly belonging to Oscillatoriales. The blooms were mainly due to Pseudanabaena spp., an unusual condition in Lake Maggiore, as this taxon commonly blooms in eutrophic water bodies (Mayer et al, 1997;Zwart et al, 2005); nonetheless, its characteristics are poorly investigated (Acinias et al, 2009) even widely distributed as it occurs in diverse aquatic as well as in benthic environments (Castenholz et al, 2001;Zwart et al, 2005;Diez et al, 2007). In the two samples collected in the central lake station, several species belonging to Oscillatoriales have contributed to the algal bloom, among which Pseudanabaena dominated, both in terms of density (68.6 and 57.0%, respectively) and biomass (47.2 and 52.6%).…”

2-Methylisoborneol production characteristics of Pseudanabaena sp. FACHB 1277 isolated from Xionghe Reservoir, China

“…, 12 days, n = 3): a variation of cell density; b variation of total 2-MIB; c variations of extracellular, dissolved intracellular, and bound intracellular 2-MIB; d variation of total 2-MIB/cell density value Discussion Identification of Pseudanabaena Pseudanabaena has drawn little attention in the scientific community where limited data exist about their phenotypic and genetic characteristics (Acinas et al 2009). Pseudanabaena species are nonheterocystous cyanobacteria belonging to the order Oscillatoriales.…”