Hidden biodiversity of the extremophilic Cyanidiales red algae

Abstract

The Cyanidiales is a group of asexual, unicellular red algae, which thrive in acidic and high temperature conditions around hot springs. These unicellular taxa have a relatively simple morphology and are currently classified into three genera, Cyanidium, Cyanidioschyzon and Galdieria. Little is known, however, about the biodiversity of Cyanidiales, their population structure and their phylogenetic relationships. Here we used a taxonomically broadly sampled three-gene data set of plastid sequences to infer a robust phylogenetic framework for the Cyanidiales. The phylogenetic analyses support the existence of at least four distinct Cyanidiales lineages: the Galdieria spp. lineage (excluding Galdieria maxima), the Cyanidium caldarium lineage, a novel monophyletic lineage of mesophilic Cyanidium spp. and the Cyanidioschyzon merolae plus Galdieria maxima lineage. Our analyses do not support the notion of a mesophilic ancestry of the Cyanidiales and suggest that these algae were ancestrally thermo-acidotolerant. We also used environmental polymerase chain reaction (PCR) for the rbcL gene to sample Cyanidiales biodiversity at five ecologically distinct sites at Pisciarelli in the Phlegrean Fields in Italy. This analysis showed a high level of sequence divergence among Cyanidiales species and the partitioning of taxa based on environmental conditions. Our research revealed an unexpected level of genetic diversity among Cyanidiales that revises current thinking about the phylogeny and biodiversity of this group. We predict that future environmental PCR studies will significantly augment known biodiversity that we have discovered and demonstrate the Cyanidiales to be a species-rich branch of red algal evolution.

Burning coal spoil heaps as a new habitat for the extremophilic red alga Galdieria sulphuraria

“…Interestingly, Galdieria is usually found growing in endolithic or interlithic habitats (Gross et al 1998;CiNiglia et al 2004;YooN et al 2006;PiNto et al 2007), however, in Ostrava site we have found the entire rich population living on the soft substrates as are the residuals of trees. First of all, organic matter can hold water which is crucial for survival and which may be limiting in low water holding capacity having soils of the spoil heaps, especially when the coal is still burning underneath the surface.…”

“…Two MCMC runs for one million generations each with one cold and three heated chains were conducted with trees sampled every 100 generations. Maximum likelihood (ML) analysis was conducted in MEGA7 (Kumar et al 2016) with 1000 bootstrap replicates using Nearest-Neighbor-Interchange and rCR (CiNiglia et al 2004). A partial fragment of calmodulin gene (CaM) of environmental Ostrava sample 2015 and strain CCALA 965 was amplified using primers Calmo 140F and Calmo 510R (YooN et al 2006).…”

“…For example, it is well known from Italy (Gross et al 1998;CiNiglia et al 2004;YooN et al 2006;PiNto et al 2007), Yellowstone National Park, USA (Ferris et al 2005;Skorupa et al 2013), New Zealand (TopliN et al 2008 and Iceland (CiNiglia et al 2014). Rocks and sediments surrounding hot sulphur springs, steaming fumaroles or boiling mud pools are typical habitats for this extremophile (Gross et al 1998;CiNiglia et al 2004CiNiglia et al , 2014Ferris et al 2005;YooN et al 2006;PiNto et al 2007;TopliN et al 2008;Skorupa et al 2013;Hsieh et al 2015). Although Galdieria is found all over the world, its distibution is discontinuous due to special growth and habitat requirements.…”

“…Contrary to the cosmopolitan species G. maxima and G. sulphuraria, G. phlegrea is known only from Italy where it was found to thrive in highly acidic non-thermophilic sites (CiNiglia et al 2004, PiNto et al 2007. Interestingly, before the discovery of the Italian strains of G. phlegrea, also described a non-thermophilic Galdieria isolated from a diatomite shield in the National Nature Reserve Soos, Czech Republic (Fig.…”

Mechanisms of Acido-Tolerance and Characteristics of Photosystems in an Acidophilic and Thermophilic Red Alga, Cyanidium Caldarium

“…No cell division occurs above pH 5 (Doemel and Brock, 1971). The extremely acidophilic nature of C. caldarium is a common feature of the Cyanidiaceae, a red algal group comprising six species, namely, Galdieria sulphuraria, Galdieria partita, Galdieria daedala, Galdieria maxima, Cyanidium caldarium and Cyanidioschyzon merolae (Albertano et al, 2000;Ciniglia et al, 2004). Among these, the complete genome of G. sulphuraria and C. merolae has been sequenced (Weber et al, 2004;Matsuzaki et al, 2004).…”