Life cycle as a stable trait in the evaluation of diversity of Nostoc from biofilms in rivers

Abstract

The diversity within the genus Nostoc is still controversial and more studies are needed to clarify its heterogeneity. Macroscopic species have been extensively studied and discussed; however, the microscopic forms of the genus, especially those from running waters, are poorly known and likely represented by many more species than currently described. Nostoc isolates from biofilms of two Spanish calcareous rivers were characterized comparing the morphology and life cycle in two culture media with different levels of nutrients and also comparing the 16S rRNA gene sequences. The results showed that trichome shape and cellular dimensions varied considerably depending on the culture media used, whereas the characteristics expressed in the course of the life cycle remained stable for each strain independent of the culture conditions. Molecular phylogenetic analysis confirmed the distinction between the studied strains established on morphological grounds. A balanced approach to the evaluation of diversity of Nostoc in the service of autecological studies requires both genotypic information and the evaluation of stable traits. The results of this study show that 16S rRNA gene sequence similarity serves as an important criterion for characterizing Nostoc strains and is consistent with stable attributes, such as the life cycle.

Description of the cyanobacterial genus Desmonostoc gen. nov. including D. muscorum comb. nov. as a distinct, phylogenetically coherent taxon related to the genus Nostoc.

“…After preliminary or partial data were previously published (Hrouzek et al 2005;PaPaeFtHiMiou et al 2008;Řeháková et al 2008;Mateo et al 2011), the existence of a unique, phylogenetically coherent clade for Desmonostoc muscorum and allied strains has been confirmed here by the addition of numerous other strains. We performed a comprehensive phylogenetic analysis including strains and species of Nostoc, Trichormus, and Mojavia that have been demonstrated in past studies to be closely related to the Desmonostoc cluster (Hrouzek et al 2005;PaPaeFtHiMiou et al 2008;Řeháková et al 2008;Mateo et al 2011); we also added a few other genera representing more distantly related Nostocaceae. Moreover, we characterized four new strains (Nostoc sp.…”

“…Previously, we noticed that in the strains of D. muscorum, hemispherical terminal heterocytes were lacking, and when terminal heterocytes were present they were oval-shaped and similar to intercalary heterocytes (Hrouzek et al 2005). However, recently, Mateo and co-authors (Mateo et al 2011), studying the life cycle of Desmonostoc MA4-UAM307 which clustered within the D1 subcluster (Fig.1), reported the occurrence of conical terminal cells on hormogonia from which terminal heterocytes differentiated. Also, we found that strain OSNI32s01 differentiated conical terminal heterocytes at the end of its hormogonia when they were developing into vegetative filaments (Fig.…”

“…8938, UAM307-MA4 and PCC 6302) belonging to strains characterized in other works, is also placed in the D2 subcluster. Strain UAM307-MA4 was isolated from a biofilm in the calcareous Marranta stream in Spain (Mateo et al 2011), while Desmonostoc sp. 8938 is a symbiont of Gunnera sp.…”

Phenotypic and genotypic characteristics ofPhormidium-like cyanobacteria inhabiting microbial mats are correlated with the trophic status of running waters

“…Thermocycling was performed using a Perkin-Elmer GeneAmp 2400 PCR system under conditions previously described by Mateo et al (2011) and following the PCR conditions of Gkelis et al (2005). For sequencing field samples (cyanobacterial mats) a Qiagen PCR Cloning plus kit (Qiagen, Hilden, Germany) was used.…”

Análise genômica e funcional da cianobactéria Nostoc sp. CENA67 e caracterização da sua comunidade microbiana associada

“…A despeito de as espécies exclusivamente microscópicas desempenharem diferentes papéis de importância ecológica na biosfera, há poucos estudos sobre elas, cujo número pode ser maior que o que está atualmente descrito (MATEO et al, 2011). Mais de 200 espécies já foram descritas dentro do gênero Nostoc; porém, com o conhecimento atual, apenas cerca de 40 espécies são reconhecidas, as quais provavelmente constituem pelo menos dois subgêneros HAUER, 2013).…”