Characterization of true‐branching cyanobacteria from geothermal sites and hot springs of Costa Rica

Abstract

Costa Rica is at the centre of the Mesoamerican biodiversity hotspot. Little is known about cyanobacteria from this region so far. Here, four isolates of the order Stigonematales (section V) were characterized in a polyphasic approach. All strains were isolated from geothermal sites and hot springs of Costa Rica. However, one of them, identified as Westiellopsis sp. Ar73, did not grow at more than 40 degrees C. Based on its identical 16S rRNA to several previously isolated Westiellopsis sp. and Fischerella muscicola strains, a ubiquitous distribution throughout tropical and subtropical regions can be implied. In contrast, the isolates MV9, MV11 and RV14 grew well up to 50-55 degrees C. Based on morphologic, ultrastructural, molecular and physiologic data, MV9, MV11 and RV14 were identified to belong to the genus Fischerella. Two distinct intergenic transcribed spacer (ITS) types, with or without tRNA genes, were detected for all Stigonematales analysed here, indicating ITS polymorphism as a characteristic feature of heterocystous cyanobacteria. In phylogenetic trees, these Fischerella spp. formed a new and distinct clade within the wider lineage of thermophilic Fischerella (Mastigocladus cf. laminosus), which might represent a geographic lineage. Thus, geographic isolation may be an underestimated aspect of microbial evolution. The strains presented here are suitable as new models to study this group of cyanobacteria.

The cyanobacterium Mastigocladus fulfills the nitrogen demand of a terrestrial hot spring microbial mat

“…Cyanobacteria have been identified in other thermal microbial mats included members of the unicellular Synechococcales (mainly the genus Synechococcus) (Sompong et al, 2005;Steunou et al, 2006Steunou et al, , 2008 and the filamentous Stigonematales (genera Fischerella and Mastigocladus) (Miller et al, 2006;Lacap et al, 2007Lacap et al, , 2007Finsinger et al, 2008). The dominating cyanobacterial phylotypes discovered in the microbial mats of the Porcelana hot spring corroborated these data, with the exception of the unicellular cyanobacteria.…”

“…Within the cyanobacteria, unicellular members such as Synechococcus and Cyanothece typically dominate at temperatures above 60°C (Ward et al, 1998;Ward and Castenholz, 2000;Papke et al, 2003;Steunou et al, 2006Steunou et al, , 2008. At lower temperatures (~60-40°C), filamentous, non-heterocystous genera such as Phormidium and Oscillatoria and heterocystous genera such as Calothrix, Fischerella and Mastigocladus are common (Sompong et al, 2005;Miller et al, 2006;Finsinger et al, 2008;Coman et al, 2013). Although heterocystous cyanobacteria are richly represented in many hot springs with a neutral pH, their role and capacity as providers of fixed nitrogen is still unknown.…”

Structure of transcription factor HetR required for heterocyst differentiation in cyanobacteria

“…Fig. S1 shows the amino acid sequences of the HetR proteins from several cyanobacterial species including Anabaena (6), Nostoc punctiforme (12), Fischerella MV11 (13), and Trichodesmium erythraeum (11). Fischerella grows at elevated temperatures, up to 60°C (13), so we thought that its HetR might provide better crystals for structure determination.…”

Cyanobacteria of the thermal spring at Pancharevo, Sofia, Bulgaria

“…Also, MILLER et al (2009) found sympatric diversification along a temperature gradient (39-54°C) as a potent source of evolution, in White Creek, Yellowstone N.P. Geographic isolation may be an important aspect of cyanophycean evolution, including Mastigocladus, studied in Costa Rica, (FINSINGER et al 2008). CASTENHOLZ (1972) forecasted the existence of the two genetic types in Mastigocladus in his paper about Surtsey Island.…”