A polyphasic taxonomic approach in isolated strains of Cyanobacteria from thermal springs of Greece

Novel diversity within Roseofilum (Desertifilaceae, Cyanobacteria) from marine benthic mats with description of four new species

Benthic cyanobacterial mats (BCMs) are natural phenomena in marine environments. Reports of BCMs occurring across coastal marine environments have increased, partly driven by nutrient loading and climate change; thus, there is a need to understand the diversity involved in the proliferations and potential toxicity of the BCMs. Furthermore, marine cyanobacterial mats are observed growing on and affecting the health of corals with one specific cyanobacterial genus, Roseofilum, dominating the microbial mats associated with black band disease (BBD), a destructive polymicrobial disease that affects corals. To explore the diversity of Roseofilum, cyanobacterial mats from various marine habitats were sampled, and individual isolates were identified based on morphology, 16S rRNA gene phylogenies, 16S-23S ITS rRNA region sequence dissimilarities, and phylogenomics. Four novel species of Roseofilum were isolated from benthic marine mats, three from the coasts of Florida, United States (R. capinflatum sp. nov., R. casamattae sp. nov., and R. acuticapitatum sp. nov.) and one from the coast of France (R. halophilum sp. nov.). Our analyses revealed that Roseofilum associated with coral BBD and those not associated with corals but rather from coastal benthic mats are systematically distinct based on both phylogenetic and phylogenomic analyses. Enzyme-linked immunosorbent assay (ELISA) and LC-MS data indicated that microcystin production was found in one of the four species.

Diverse Microbial Hot Spring Mat Communities at Black Canyon of the Colorado River

The thermophilic microbial mat communities at hot springs in the Black Canyon of the Colorado River, thought to harbor the protistan human pathogen Naegleria fowleri, were surveyed using both culture-independent and -dependent methods to further understand the ecology of these hot spring microbiomes. Originating from Lake Mead source water, seven spring sites were sampled, varying in temperature from 25 to 55 °C. Amplicon-based high-throughput sequencing of twelve samples using 16S rRNA primers (hypervariable V4 region) revealed that most mats are dominated by cyanobacterial taxa, some but not all similar to those dominating the mats at other studied hot spring systems. 18S rRNA amplicon sequencing (V9 region) demonstrated a diverse community of protists and other eukaryotes including a highly abundant amoebal sequence related to Echinamoeba thermarum. Additional taxonomic and diversity metric analyses using near full-length 16S and 18S rRNA gene sequencing allowed a higher sequence-based resolution of the community. The mat sequence data suggest a major diversification of the cyanobacterial orders Leptolyngbyales, as well as microdiversity among several cyanobacterial taxa. Cyanobacterial isolates included some representatives of ecologically abundant taxa. A Spearman correlation analysis of short-read amplicon sequencing data supported the co-occurrences of populations of cyanobacteria, chloroflexi, and bacteroidetes providing evidence of common microbial co-occurrences across the Black Canyon hot springs.

Cartusia hunanesis sp. nov. (Oculatellaceae, Oculatellales) from a Stream in China Based on Polyphasic Approach

Cartusia hunanesis sp. nov. was isolated from a stream in China, and two strains (ZJJ02 and ZJJ03) of which were inquired using morphological features, ecological evidence, and molecular data consisting of the 16S rRNA gene and 16S–23S rRNA intergenic transcribed spacer (ITS) region. Cartusia hunanesis varies from the type species Cartusia fontana by having only a single trichome in the sheath and large granules near the cross wall. The investigated strains of C. hunanesis were revealed to be a sister clade of C. fontana, according to the phylogenetic analysis based on the 16S rRNA gene. In addition, the Cartusia was clustered with the family Oculatellaceae members, genera Pegethrix and Elainella. These two strains displayed 97.6% similarity to C. fontana. The ITS region of C. hunanesis was found to be considerably distinct from that of C. fontana in terms of the secondary structure, which demonstrated that C. hunanesis is a novel species owing to the divergences in its morphological and genetic data compared with the related C. fontana.

Trichotorquatus salinus sp. nov. (Oculatellaceae, Cyanobacteria) from a Saltern of Gomso, Republic of Korea

Six strains of subaerial cyanobacteria were isolated from a Gomso saltern in the Republic of Korea, all of which were studied using morphological and molecular traits. Trichotorquatus salinus sp. nov. was studied using a light microscope (LM), transmission electron microscope (TEM), 16S rRNA, 16S–23S ITS region, and ecological data. T. salinus is a thin and simple filament with a false branch and a firm collar sheath. The phylogenetic analyses of 16S rRNA revealed that Trichotorquatus formed a monophyletic lineage and the strains of T. salinus formed a distinct clade among the species in the genus Trichotorquatus. In the statistical analysis, the inter-species genetic distance of the five species of Trichotorquatus, including T. salinus, is shown to be greater than the distance of the previously reported species of Trichotorquatus. Additionally, 16S–23S ITS gene sequences between T. salinus and four species of Trichotorquatus showed dissimilarities of 55.3–59.4%. In the secondary structure of 16S–23S ITS region (type 2 operon), D1–D1′, Box-B, and V3 helix of T. salinus were different from the other taxa in the genus Trichotorquatus. These results demonstrate that T. salinus sp. nov. has unique morphological, ecological, and molecular traits. Therefore, we propose that T. salinus sp. nov. is a novel species belonging to the genus Trichotorquatus.

Cyanobacteria in hot pursuit: Characterization of cyanobacteria strains, including novel taxa, isolated from geothermal habitats from different ecoregions of the world

Well-studied thermal spring microbial mat systems continue to serve as excellent models from which to make discoveries of general importance to microbial community ecology in order to address comprehensively the question of "who is there" in a microbial community. Cyanobacteria are highly adaptable and an integral part of many ecosystems including thermal springs. In this context, we sampled disparate thermal springs, spanning from Iceland and Poland to Greece and Tajikistan. Thirteen (13) strains were isolated and characterised with taxonomic indices and molecular markers (16S-23S rRNA region and cpcBA gene), whilst their thermotolerance was evaluated. Screening for the presence of genes encoding three heat shock proteins, as well as non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) was performed. This approach resulted in the description of two new genera (Hillbrichtia and Amphirytos) and their type species (Hillbrichtia pamiria and Amphirytos necridicus) representing Oscillatoriales and Synechococcales orders, respectively. We also found unique lineages inside the genus Thermoleptolyngbya, describing a novel species (T. hindakiae). We described the presence of sub-cosmopolitan taxa (such as Calothrix, Desertifilum, and Trichormus). Strains were diverse concerning their thermophilic ability with the strains well adapted to high temperatures possessing all three investigated genes encoding heat shock proteins as well as studied PKS and NRPS genes. In this work, we show novel cyanobacteria diversity from thermal springs from disparate environments, possible correlation of thermotolerance and their genetic background, which may have implications on strategic focusing of screening programs on underexploited taxa in these habitats.

Unravelling unknown cyanobacteria diversity linked with HCN production

Cyanobacteria are ecologically versatile microorganisms, occupying diverse habitats, from terrestrial caves to coastal shores and from brackish lakes to thermal springs. Cyanobacteria have also been linked with hydrogen cyanide (HCN), mainly for their ability to catabolize HCN by the nitrogenase enzyme. In this context, we sampled disparate environments, spanning from Canary Islands and Iceland to Estonia and Cyprus. Eighty-one (81) strains were isolated and characterised with taxonomic indices and molecular markers (16S-23S rRNA region and cpcBA region), whilst their ability to produce HCN was evaluated. This approach resulted in the description of five new genera (Speleotes, Haliplanktos, Olisthonema, Speos, and Iphianassa) and their type species (S. anchialus, H. antonyquinny, O. eestii, S. fyssassi, I. zackieohae) representing Chroococcales, Chroococcidiopsales, Oscillatoriales, Synechococcales, and Nostocales orders, respectively. We also found unique lineages inside the genera Komarekiella, Stenomitos, Cyanocohniella, and Nodularia, describing four new species (K. chia, S. pantisii, C. hyphalmyra, N. mediterannea). We report for the first time a widespread production of HCN amongst different taxa and habitats. Epilithic lifestyle, where cyanobacteria are more vulnerable to grazers, had the largest relative frequency in HCN production. In this work, we show novel cyanobacteria diversity from various habitats, including an unexplored anchialine cave, and possible correlation of cyanobacteria chemo- with species diversity, which may have implications on strategic focusing of screening programs on underexploited taxa and/or habitats.

Description, Taxonomy, and Comparative Genomics of a Novel species, Thermoleptolyngbya sichuanensis sp. nov., Isolated From Hot Springs of Ganzi, Sichuan, China

Thermoleptolyngbya is a newly proposed genus of thermophilic cyanobacteria that are often abundant in thermal environments. However, a vast majority of Thermoleptolyngbya strains were not systematically identified, and genomic features of this genus are also sparse. Here, polyphasic approaches were employed to identify a thermophilic strain, PKUAC-SCTA183 (A183 hereafter), isolated from hot spring Erdaoqiao, Ganzi prefecture, China. Whole-genome sequencing of the strain revealed its allocation to Thermoleptolyngbya sp. and genetic adaptations to the hot spring environment. While the results of 16S rRNA were deemed inconclusive, the more comprehensive polyphasic approach encompassing phenetic, chemotaxic, and genomic approaches strongly suggest that a new taxon, Thermoleptolyngbya sichuanensis sp. nov., should be delineated around the A183 strain. The genome-scale phylogeny and average nucleotide/amino-acid identity confirmed the genetic divergence of the A183 strain from other strains of Thermoleptolyngbya along with traditional methods such as 16S-23S ITS and its secondary structure analyses. Comparative genomic and phylogenomic analyses revealed inconsistent genome structures between Thermoleptolyngbya A183 and O-77 strains. Further gene ontology analysis showed that the unique genes of the two strains were distributed in a wide range of functional categories. In addition, analysis of genes related to thermotolerance, signal transduction, and carbon/nitrogen/sulfur assimilation revealed the ability of this strain to adapt to inhospitable niches in hot springs, and these findings were preliminarily confirmed using experimental, cultivation-based approaches.

Microbiota of the Therapeutic Euganean Thermal Muds with a Focus on the Main Cyanobacteria Species

The Euganean Thermal District has been known since Roman times for the therapeutic properties of peloids, obtained from natural clays that have undergone a traditional maturation process. This leads to the growth of a green microbial biofilm with Cyanobacteria and the target species Phormidium sp. ETS-05 as fundamental components for their ability to synthetize anti-inflammatory molecules. Currently, in-depth studies on the microbiota colonizing Euganean peloids, as in general on peloids utilized worldwide, are missing. This is the first characterization of the microbial community of Euganean thermal muds, also investigating the effects of environmental factors on its composition. We analysed 53 muds from 29 sites (Spas) using a polyphasic approach, finding a stable microbiota peculiar to the area. Differences among mud samples mainly depended on two parameters: water temperature and shading of mud maturation plants. In the range 37-47 °C and in the case of irradiance attenuation due to the presence of protective roofs, a statistically significant higher mud Chl a content was detected. Moreover, in these conditions, a characteristic microbial and Cyanobacteria population composition dominated by Phormidium sp. ETS-05 was observed. We also obtained the complete genome sequence of this target species using a mixed sequencing approach based on Illumina and Nanopore sequencing.

Cyanobacteria Phylogenetic Studies Reveal Evidence for Polyphyletic Genera from Thermal and Freshwater Habitats

Cyanobacteria are among the most diverse morphological microorganisms that inhabit a great variety of habitats. Their presence in the Azores, a volcanic archipelago of nine islands in the middle of the North Atlantic Ocean, has already been reported. However, due to the high diversity of cyanobacteria habitats, their biodiversity is still understudied, mainly in extreme environments. To address this, a total of 156 cyanobacteria strains from Azores lakes, streams, thermal and terrestrial habitats were isolated. Identification was made based on a polyphasic approach using classical taxonomy (morphological characteristics and environmental data) and phylogeny among 81 strains assessed by maximum likelihood and Bayesian analysis of 16S rDNA partial sequences. The 156 isolates showed a high genera diversity (38) belonging to the orders Chroococcales, Nostocales, Oscillatoriales, and Synechococcales. Eleven new genera for the Azores habitats are here reported, reinforcing that cyanobacteria biodiversity in these islands is still much understudied. Phylogenetic analysis showed 14 clusters associated with these cyanobacteria orders, with evidence for six new genera and valuable information towards Microchaete/Coleospermum taxonomic revision that better reflects species environmental distribution. These results emphasize the need for cyanobacteria taxonomy revisions, through polyphasic studies, mainly in Synechococcales order and in the Microchaete/Coleospermum, Nostoc, and Anabaena genera.

Polyphasic taxonomy of green algae strains isolated from Mediterranean freshwaters

Background

Terrestrial, freshwater and marine green algae constitute the large and morphologically diverse phylum of Chlorophyta, which gave rise to the core chlorophytes. Chlorophyta are abundant and diverse in freshwater environments where sometimes they form nuisance blooms under eutrophication conditions. The phylogenetic relationships among core chlorophyte clades (Chlorodendrophyceae, Ulvophyceae, Trebouxiophyceae and Chlorophyceae), are of particular interest as it is a species-rich phylum with ecological importance worldwide, but are still poorly understood. In the Mediterranean ecoregion, data on molecular characterization of eukaryotic microalgae strains are limited and current knowledge is based on ecological studies of natural populations. In the present study we report the isolation and characterization of 11 green microalgae strains from Greece contributing more information for the taxonomy of Chlorophyta. The study combined morphological and molecular data.

Results

Phylogenetic analysis based on 18S rRNA, internal transcribed spacer (ITS) region and the large subunit of the ribulose-bisphosphate carboxylase (rbcL) gene revealed eight taxa. Eleven green algae strains were classified in four orders (Sphaeropleales, Chlorellales, Chlamydomonadales and Chaetophorales) and were represented by four genera; one strain was not assigned to any genus. Most strains (six) were classified to the genus Desmodesmus, two strains to genus Chlorella, one to genus Spongiosarcinopsis and one filamentous strain to genus Uronema. One strain is placed in a separate independent branch within the Chlamydomonadales and deserves further research.

Conclusions

Our study reports, for the first time, the presence of Uronema in an aquatic environment up to 40 °C and reveals new diversity within the Chlamydomonadales. The results from the ITS region and the rbcL gene corroborated those obtained from 18S rRNA without providing further information or resolving the phylogenetic relationships within certain genera, due to the limited number of ITS and rbcL sequences available. The comparison of molecular and morphological data showed that they were congruent. Cosmopolitan genera with high worldwide distribution inhabit Greek freshwaters.

Molecular Characterization of Twenty-Five Marine Cyanobacteria Isolated from Coastal Regions of Ireland

Twenty-five marine cyanobacteria isolated from Irish coasts were characterized based on their morphological characters and 16S rRNA gene sequence analysis. In addition, superoxide dismutase (SOD) and malate dehydrogenase (MDH) isoenzyme banding patterns were used to differentiate two morphologically ambiguous isolates. In this study, six new cyanobacteria-specific primers were designed, and a 16S rRNA gene of twenty-five morphologically diverse cyanobacteria was successfully PCR amplified (1198–1396 bps). Assembled 16S rRNA sequences were used both for a basic local alignment search tool (BLAST) analysis for genus-level identification and to generate a phylogenetic tree, which yielded two major clusters: One with morphologically homogenous cyanobacteria and the other with morphologically very diverse cyanobacteria. Kamptonema okenii and Tychonema decoloratum were isolated from a single field sample of Ballybunion and were originally identified as the same ‘Oscillatoria sp.’ based on preliminary morphological observations. However, an alignment of 16S rRNA gene sequences and SOD and MDH isoenzyme banding pattern analyses helped in differentiating the morphologically-indistinguishable ‘Oscillatoria sp.’. Finally, after a re-evaluation of their morphological characters using modern taxonomic publications, the originally identified ‘Oscillatoria sp.’ were re-identified as Kamptonema okenii and Tychonema decoloratum, thus supporting the polyphasic approach of cyanobacteria characterization.

A bridge too far in naming species: a total evidence approach does not support recognition of four species in Desertifilum (Cyanobacteria)

A population of Desertifilum (Cyanobacteria, Oscillatoriales) from an oligotrophic desertic biotope was isolated and characterized using a polyphasic approach including molecular, morphological, and ecological information. The population was initially assumed to be a new species based on ecological and biogeographic separation from other existing species, however, phylogenetic analyses based on sequences of the 16S rRNA gene and 16S-23S ITS region, placed this strain clearly within the type species, Desertifilum tharense. Comparative analysis of morphology, 16S rRNA gene similarity, 16S-23S ITS secondary structure, and percent dissimilarity of the ITS regions for all characterized strains supports placing the six Desertifilum strains (designated as PD2001/TDC17, UAM-C/S02, CHAB7200, NapGTcm17, IPPAS B-1220, and PMC 872.14) into D. tharense. The recognition of Desertifilum salkalinema and Desertifilum dzianense is not supported, although our analysis does support continued recognition of Desertifilum fontinale. Pragmatic criteria for recognition of closely related species are proposed based on this study and others, and more rigorous review of future taxonomic papers is recommended.

The Biosynthesis of Rare Homo-Amino Acid Containing Variants of Microcystin by a Benthic Cyanobacterium

Microcystins are a family of chemically diverse hepatotoxins produced by distantly related cyanobacteria and are potent inhibitors of eukaryotic protein phosphatases 1 and 2A. Here we provide evidence for the biosynthesis of rare variants of microcystin that contain a selection of homo-amino acids by the benthic cyanobacterium Phormidium sp. LP904c. This strain produces at least 16 microcystin chemical variants many of which contain homophenylalanine or homotyrosine. We retrieved the complete 54.2 kb microcystin (mcy) gene cluster from a draft genome assembly. Analysis of the substrate specificity of McyB₁ and McyC adenylation domain binding pockets revealed divergent substrate specificity sequences, which could explain the activation of homo-amino acids which were present in 31% of the microcystins detected and included variants such as MC-LHty, MC-HphHty, MC-LHph and MC-HphHph. The mcy gene cluster did not encode enzymes for the synthesis of homo-amino acids but may instead activate homo-amino acids produced during the synthesis of anabaenopeptins. We observed the loss of microcystin during cultivation of a closely related strain, Phormidium sp. DVL1003c. This study increases the knowledge of benthic cyanobacterial strains that produce microcystin variants and broadens the structural diversity of known microcystins.

Extending the ecological distribution of Desmonostoc genus: proposal of Desmonostoc salinum sp. nov., a novel Cyanobacteria from a saline-alkaline lake

Cyanobacteria is an ancient phylum of oxygenic photosynthetic microorganisms found in almost all environments of Earth. In recent years, the taxonomic placement of some cyanobacterial strains, including those belonging to the genus Nostocsensu lato, have been reevaluated by means of a polyphasic approach. Thus, 16S rRNA gene phylogeny and 16S-23S internal transcribed spacer (ITS) secondary structures coupled with morphological, ecological and physiological data are considered powerful tools for a better taxonomic and systematics resolution, leading to the description of novel genera and species. Additionally, underexplored and harsh environments, such as saline-alkaline lakes, have received special attention given they can be a source of novel cyanobacterial taxa. Here, a filamentous heterocytous strain, Nostocaceae CCM-UFV059, isolated from Laguna Amarga, Chile, was characterized applying the polyphasic approach; its fatty acid profile and physiological responses to salt (NaCl) were also determined. Morphologically, this strain was related to morphotypes of the Nostocsensu lato group, being phylogenetically placed into the typical cluster of the genus Desmonostoc. CCM-UFV059 showed identity of the 16S rRNA gene as well as 16S-23S secondary structures that did not match those from known described species of the genus Desmonostoc, as well as distinct ecological and physiological traits. Taken together, these data allowed the description of the first strain of a member of the genus Desmonostoc from a saline-alkaline lake, named Desmonostoc salinum sp. nov., under the provisions of the International Code of Nomenclature for algae, fungi and plants. This finding extends the ecological coverage of the genus Desmonostoc, contributing to a better understanding of cyanobacterial diversity and systematics.

Phenotypic and genotypic characterisation of an unique indigenous hypersaline unicellular cyanobacterium, Euhalothece sp.nov

A novel halotolerant species of cyanobacterium of the order Chroococcales was isolated from hypersaline estuary in Kwa-Zulu Natal, South Africa. A comprehensive polyphasic approach viz., cell morphology, pigment composition and complete genome sequence analysis was conducted to elucidate the taxonomic position of the isolated strain. The blue-green oval to rod-shaped cells were 14-18 μm in size, and contained a high amount of phycocyanin pigments. The strain was moderate thermotolerant/alkalitolerant halophile with the optimum conditions for growth at 35 °C, pH 8.5 and 120 g/l of NaCl. Based on 16S rRNA gene sequence phylogeny, the strain was related to members of the 'Euhalothece' subcluster (99%). The whole genome sequence was determined, and the annotated genes showed a 90% sequence similarity to the gas-vacuolate, spindle-shaped Dactylococcopsis salina PCC 8305. The size of the genome was determined to be 5,113,178 bp and contained 4332 protein-coding genes and 69 RNA genes with a G + C content of 46.7%. Genes encoding osmoregulation, oxidative stress, heat shock, persister cells, and UV-absorbing secondary metabolites, among others, were identified. Based on the phylogenetic analysis of the 16S rRNA gene sequences, physiological data, pigment compositions and genomic data, the strain is considered to represent a novel species of Euhalothece.

Diversity and bioactivities of nostocacean cyanobacteria isolated from paddy soil in Vietnam

Nostocacean cyanobacteria are one of the important components of paddy fields due to their ability to fix atmospheric nitrogen and supply phytohormones for crop growth. In this study, 13 Nostoc strains isolated from paddy soils in Vietnam were classified using a polyphasic approach. The results showed a high diversity of the isolated strains that represented seven morphotypes corresponding to five genotypes, with 16S rRNA gene sequence similarity values ranging between 94.97-99.78% compared to the available sequences from GenBank. Bioassay assessment revealed that 11 out of 13 strains possessed antibacterial activities, three of which exhibited cytotoxic activities on MCF7 and HCT116 cells with an IC₅₀ ranging from 47.8μgmL^-1 to 232.0μgmL^-1. Interestingly, strains with identical 16S rRNA gene sequences displayed different antibacterial and cytotoxic activity profiles.

A widespread cyanobacterium supported by polyphasic approach: proposition of Koinonema pervagatum gen. & sp. nov. (Oscillatoriales)1

Several new genera originally classified as the genus Phormidium, a polyphyletic and taxonomically complex genus within the Oscillatoriales, were recently described. The simple morphology of Phormidium does not reflect its genetic diversity and the delimitation of a natural group is not possible with traditional classification systems based on morphology alone. Therefore, this study used morphological, ecological, and molecular approaches to evaluate four populations morphologically similar to Ammassolinea, Kamptonema, and Ancylothrix (simple, curved, and gradually attenuated at the ends trichome), found in subtropical and tropical Brazilian regions. 16S rRNA gene sequences grouped all the strains in a highly supported clade with other two European strains isolated from thermal springs surrounding areas. The 16S-23S ITS secondary structure corroborated the phylogenetic analysis with all the strains having similar structures. Consequently, a genetically well-defined and cryptic new genus, Koinonema gen. nov., is proposed containing the aquatic, mesophilic, and morphologically homogeneous new species, Koinonema pervagatum sp. nov.

Iningainema pulvinus gen nov., sp nov. (Cyanobacteria, Scytonemataceae) a new nodularin producer from Edgbaston Reserve, north-eastern Australia

A new nodularin producing benthic cyanobacterium Iningainema pulvinus gen nov., sp nov. was isolated from a freshwater ambient spring wetland in tropical, north-eastern Australia and characterised using combined morphological and phylogenetic attributes. It formed conspicuous irregularly spherical to discoid, blue-green to olive-green cyanobacterial colonies across the substratum of shallow pools. Morphologically Iningainema is most similar to Scytonematopsis Kiseleva and Scytonema Agardh ex Bornet & Flahault. All three genera have isopolar filaments enveloped by a firm, often layered and coloured sheath; false branching is typically geminate, less commonly singly. Phylogenetic analyses using partial 16S rRNA sequences of three clones of Iningainema pulvinus strain ES0614 showed that it formed a well-supported monophyletic clade. All three clones were 99.7-99.9% similar, however they shared less than 93.9% nucleotide similarity with other cyanobacterial sequences including putatively related taxa within the Scytonemataceae. Amplification of a fragment of the ndaF gene involved in nodularin biosynthesis from Iningainema pulvinus confirmed that it has this genetic determinant. Consistent with these results, analysis of two extracts from strain ES0614 by HPLC-MS/MS confirmed the presence of nodularin at concentrations of 796 and 1096μgg^-1 dry weight. This is the third genus of cyanobacteria shown to produce the cyanotoxin nodularin and the first report of nodularin synthesis from the cyanobacterial family Scytonemataceae. These new findings may have implications for the aquatic biota at Edgbaston Reserve, a spring complex which has been identified as a priority conservation area in the central Australian arid and semiarid zones, based on patterns of endemicity.

Cyanobacteria of Greece: an annotated checklist

Background

The checklist of Greek Cyanobacteria was created in the framework of the Greek Taxon Information System (GTIS), an initiative of the LifeWatchGreece Research Infrastructure (ESFRI) that has resumed efforts to compile a complete checklist of species reported from Greece. This list was created from exhaustive search of the scientific literature of the last 60 years. All records of taxa known to occur in Greece were taxonomically updated.

New information

The checklist of Greek Cyanobacteria comprises 543 species, classified in 130 genera, 41 families, and 8 orders. The orders Synechococcales and Oscillatoriales have the highest number of species (158 and 153 species, respectively), whereas these two orders along with Nostocales and Chroococcales cover 93% of the known Greek cyanobacteria species. It is worth mentioning that 18 species have been initially described from Greek habitats. The marine epilithic Ammatoideaaegea described from Saronikos Gulf is considered endemic to this area. Our bibliographic review shows that Greece hosts a high diversity of cyanobacteria, suggesting that the Mediterranean area is also a hot spot for microbes.

Detection of the new cosmopolitan genus Thermoleptolyngbya (Cyanobacteria, Leptolyngbyaceae) using the 16S rRNA gene and 16S-23S ITS region

Cyanobacteria are widespread prokaryotes that are able to live in extreme conditions such as thermal springs. Strains attributable to the genus Leptolyngbya are among the most common cyanobacteria sampled from thermal environments. Leptolyngbya is a character-poor taxon that was demonstrated to be polyphyletic based on molecular analyses. The recent joining of 16S rRNA gene phylogenies with 16S-23S ITS secondary structure analysis is a useful approach to detect new cryptic taxa and has led to the separation of new genera from Leptolyngbya and to the description of new species inside this genus and in other related groups. In this study, phylogenetic investigations based on both the 16S rRNA gene and the 16S-23S ITS region were performed alongside 16S rRNA and 16S-23S ITS secondary structure analyses on cyanobacteria of the family Leptolyngbyaceae. These analyses focused on filamentous strains sampled from thermal springs with a morphology ascribable to the genus Leptolyngbya. The phylogenetic reconstructions showed that the Leptolyngbya-like thermal strains grouped into a monophyletic lineage that was distinct from Leptolyngbya. The 16S-23S ITS secondary structure results supported the separation of this cluster. A new genus named Thermoleptolyngbya was erected to encompass these strains, and two species were described inside this new taxon: T. albertanoae and T. oregonensis.