Amazonocrinis nigriterrae gen. nov., sp. nov., Atlanticothrix silvestris gen. nov., sp. nov. and Dendronalium phyllosphericum gen. nov., sp. nov., nostocacean cyanobacteria from Brazilian environments

Expanding the cyanobacterial flora of India: Multiple novel species of Nostoc and Desmonostoc from Jammu and Kashmir, India using a polyphasic approach

This investigation reports the polyphasic characterization of six cyanobacterial strains that were isolated from Basantgarh village of district Udhampur in the union territory of Jammu and Kashmir, India. Morphological examination of the isolated strains indicated that the strains are members of the genus Nostoc or its morphotypes. Phylogenetic analyses using the 16S rRNA gene showed that five strains clustered in the Nostoc sensu stricto clade, whereas one strain clustered in the Desmonostoc clade. Further, comparative studies with their phylogenetically related taxa, based on morphology, folded secondary structures, phylogeny of the ITS rRNA region, and the percent genetic homology of 16S rRNA gene and ITS rRNA region clearly established the strains as novel taxa belonging to the genera Nostoc and Desmonostoc. Also, two strains 21A-PS and 2JNA-PS emerged as conspecific to each other, representing the same species of Nostoc. Hence, in accordance with the International code of Nomenclature for algae, fungi, and plants, this study describes Nostoc jammuense, Nostoc globosum, Nostoc breve, and Nostoc coriaceum, as novel species of the genus Nostoc, while Desmonostoc raii is described as a novel species of the genus Desmonostoc. This study adds novel species of Nostoc from Indian habitats and reinforces the need to explore the Nostoc sensu stricto clade for more novel taxa.

Igniting taxonomic curiosity: The amazing story of Amazonocrinis with the description of a new genus Ahomia gen. nov. and novel species of Ahomia, Amazonocrinis, and Dendronalium from the biodiversity-rich northeast region of India

Five cyanobacterial strains exhibiting Nostoc-like morphology were sampled from the biodiversity hotspots of the northeast region of India and characterized using a polyphasic approach. Molecular and phylogenetic analysis using the 16S rRNA gene indicated that the strains belonged to the genera Amazonocrinis and Dendronalium. In the present investigation, the 16S rRNA gene phylogeny clearly demarcated two separate clades of Amazonocrinis. The strain MEG8-PS clustered along with Amazonocrinis nigriterrae CENA67, which is the type strain of the genus. The other three strains ASM11-PS, RAN-4C-PS, and NP-KLS-5A-PS clustered in a different clade that was phylogenetically distinct from the Amazonocrinis sensu stricto clade. Interestingly, while the 16S rRNA gene phylogeny exhibited two separate clusters, the 16S-23S ITS region analysis did not provide strong support for the phylogenetic observation. Subsequent analyses raised questions regarding the resolving power of the 16S-23S ITS region at the genera level and the associated complexities in cyanobacterial taxonomy. Through this study, we describe a novel genus Ahomia to accommodate the members clustering outside the Amazonocrinis sensu stricto clade. In addition, we describe five novel species, Ahomia kamrupensis, Ahomia purpurea, Ahomia soli, Amazonocrinis meghalayensis, and Dendronalium spirale, in accordance with the International Code of Nomenclature for algae, fungi, and plants (ICN). Apart from further enriching the genera Amazonocrinis and Dendronalium, the current study helps to resolve the taxonomic complexities revolving around the genus Amazonocrinis and aims to attract researchers to the continued exploration of the tropical and subtropical cyanobacteria for interesting taxa and lineages.

Albertania and Egbenema gen. nov. from Nigeria and the United States, expanding biodiversity in the Oculatellaceae (cyanobacteria)

Knowledge of the tropical terrestrial cyanobacterial flora from the African continent is still limited. Of 31 strains isolated from soil and subaerial samples collected in Lagos State, Nigeria, three were found to be in the Oculatellaceae, including two species in a new genus. Subsequently, isolates from microbial mats in White Sands National Park in New Mexico, United States, and from a rock near the ocean in Puerto Rico, United States, were found to belong to the new genus as well. Cyanobacterial isolates were characterized microscopically, sequenced for the 16S rRNA gene and associated ITS region, and phylogenetically analyzed. Egbenema gen. nov., with three new species, as well as two new species of Albertania were differentiated from all other Oculatellaceae. Both genera belong to a supported clade within the Oculatellaceae that includes Trichotorquatus and Komarkovaea. The two new species of Albertania, A. egbensis and A. latericola, were from the same sample, but were evolutionarily separate based on 16S rRNA gene phylogenies, percent identity below the 98.7% threshold, and ITS rRNA percent dissimilarity >7.0%. Egbenema aeruginosum gen. et sp. nov. was phylogenetically separated from Trichotorquatus and Albertania but was in a clade with other strains belonging to Egbenema. The two Egbenema strains from the United States are here named Egbenema epilithicum sp. nov. and Egbenema gypsiphilum sp. nov. Our results support the hypothesis that further species discoveries of novel cyanobacteria will likely be made in soils and subaerial habitats, as these habitats continue to be studied, both in tropical and temperate biomes.

How diverse a genus can be: An integrated multi-layered analysis into Desmonostoc (Nostocaceae, Cyanobacteriota)

Cyanobacteria (Phylum Cyanobacteriota) are Gram-negative bacteria capable of performing oxygenic photosynthesis. Although the taxonomic classification of cyanobacteria was for a long time based primarily on morphological characters, the application of other techniques (e.g. molecular phylogeny), especially in recent decades, has contributed to a better resolution of cyanobacteria systematics, leading to a revision of the phylum. Although Desmonostoc occurs as a new genus/cluster and some species have been described recently, relatively few studies have been carried out to elucidate its diversity, which encompasses strains from different ecological origins, or examine the application of new characterization tools. In this context, the present study investigated the diversity within Desmonostoc, based on morphological, molecular, metabolic, and physiological characteristics. Although the usage of physiological parameters is unusual for a polyphasic approach, they were efficient in the characterization performed here. The phylogenetic analysis based on 16S rRNA gene sequences put all studied strains (25) into the D1 cluster and indicated the emergence of novel sub-clusters. It was also possible to observe that nifD and nifH exhibited different evolutionary histories within the Desmonostoc strains. Collectively, metabolic and physiological data, coupled with the morphometric data, were in general, in good agreement with the separation based on the phylogeny of the 16S rRNA gene. Furthermore, the study provided important information on the diversity of Desmonostoc strains collected from different Brazilian biomes by revealing that they were cosmopolitan strains, acclimatized to low luminous intensities, with a large metabolic diversity and great biotechnological potential.

Insights into the phylogenetic inconsistencies of the genus Amazonocrinis and description of epilithic Amazonocrinis malviyae sp. nov. (Cyanobacteria, Nostocales) from Jammu and Kashmir, India

A dark-coloured thin film of cyanobacteria growing on the bottom of a submerged stone was isolated from Basantgarh village in Udhampur district, Jammu and Kashmir, India. The isolated strain (designated 19C-PS^T) was characterized using a polyphasic approach. The strain exhibited typical Nostoc-like morphology with a characteristic feature of having heterocytes in series. The 16S rRNA gene phylogeny placed the strain at a well-supported and distinct node. Notably, the recently described genus, Amazonocrinis, on the addition of more 16S rRNA gene sequences, reflected a critical split, which proved to be stable and well supported in all phylogenetic analyses of the 16S rRNA gene. Interestingly, Amazonocrinis nigriterrae CENA67^T (type species of the genus) clustered together with our strain 19C-PS^T in the 16S rRNA gene phylogenetic analysis while the rest of the members of the genus Amazonocrinis were placed at a separate and distant node. This clearly indicated that strain 19C-PS^T is a member of Amazonocrinis sensu stricto. However, the results of phylogenetic analysis of ITS sequences only, in strains purported to belong to Amazonocrinis did not agree with the 16S rRNA gene results and placed our strain 19C-PS^T in a sister clade to three strains that have not yet been speciated, UHCC 0702, NIES-4103 and SA22, with A. nigriterrae falling into a separate clade. Further, folded secondary structures of the D1-D1', V2, BoxB and V3 helices of strain 19C-PS^T were found to be significantly different from those of all the phylogenetically related taxa. The study revealed an interesting case where low taxon sampling and phylogenomic interpretations came across as points of attention in cyanobacterial taxonomy. Based on the morphological, phylogenetic, 16S-23S ITS secondary structure analyses, we describe our strain as Amazonocrinis malviyae sp. nov. in accordance with the International Code of Nomenclature for algae, fungi and plants. This work also illuminates the need for further research to resolve the taxonomic discrepancies among Amazonocrinis strains.

Phycological exploration of the global biodiversity hotspots of Northeast India: discovery of a new species of soil-dwelling cyanobacteria, Desikacharya kailashaharensis sp. nov

A soil-dwelling cyanobacterial strain (KLS-BP-3A_PS), has been isolated from the biodiversity rich Northeast region of India and characterized using a polyphasic approach. The strain was collected from a field covered with grass, near a stream from the Unakoti district of Tripura. Upon culturing in the laboratory, initial studies indicated the strain to be showing typical Nostoc or Nostoc-like morphology. Subsequently, 16S rRNA gene phylogenetic analyses using Neighbour joining, Maximum-likelihood, and Bayesian inference methods gave a distinct and stable positioning of the strain inside the genus Desikacharya. Upon recovery of the full-length operon of the 16S-23S ITS region with both tRNAs (tRNAIle and tRNAAla), the folded secondary structures revealed unique patterns of the D1-D1', V2, Box-B, and V3 regions of the strain KLS-BP-3A_PS as compared to phylogenetically related species of the genus Desikacharya. The total evidence approach indicated conclusively that the strain under investigation is a new species of the genus Desikacharya, which we describe as Desikacharya kailashaharensis in accordance with the International Code of Nomenclature for algae, fungi, and plants. Further, 16S rRNA gene phylogeny and evaluation of the 16S-23S ITS operons along with implying a re-examination of the family level affiliation of Desikacharya as well its generic limits may be in order. Notably, this study brings into focus the very less explored Northeast region of India which shares two global biodiversity hotspots in the world.

Polyphasic evaluation and cytotoxic investigation of isolated cyanobacteria with an emphasis on potent activities of a Scytonema strain

Cyanobacteria are phototrophic organisms widely found in most types of natural habitats in the tropical regions of the world. In this study, we isolated and identified cyanobacterial strains from paddy soil in Hanoi (Vietnam) and investigated their cytotoxic activities. Five isolated cyanobacterial strains showed distinctive profiles of gene sequences (rRNA 16S and rbcL), phylogenetic placements, and morphological characteristics. Based on the polyphasic evaluation, they were classified as Scytonema bilaspurense NK13, Hapalosiphon welwitschii MD2411, Aulosira sp. XN1103, Desikacharya sp. NS2000, and Desmonostoc sp. NK1813. The cytotoxic screening revealed that the extract of strain Scytonema bilaspurense NK13 exhibited potent cytotoxic activities against four human cell lines of HeLa cells, OVCAR-8 cells, HaCaT cells, and HEK-293T cells, with IC50 values of 3.8, 34.2, 21.6, and 0.6 μg/mL, respectively. This is the first time a well-classified Scytonema strain from tropical habitat in Southeast Asia has been recognized as a potential producer of cytotoxic compounds.

Digging deeper into the taxonomy of Cylindrospermum and description of Johanseniella tripurensis gen. et sp. nov. from India

The wet soil-inhabiting cyanobacterium URH-6-PS was collected from the state of Tripura, India, and characterized using a polyphasic approach. Initial microscopic analysis indicated the strain to be a member of the genus Cylindrospermum, however, the 16S rRNA gene phylogenetic analysis showed some interesting results. The strain URH-6-PS clustered in the Clade I which positioned itself outside the Cylindrospermum sensu stricto clade with strong probability/bootstrap support, indicating that the strain may not belong to the genus Cylindrospermum. Further, analysis of the 16S-23S ITS region using the folded secondary structures of the D1-D1', Box-B and V3 helices and the 16S-23S ITS percentage dissimilarity values clearly indicated the distinctiveness of strain URH-6-PS from other members of the Clade I. The detailed investigations conducted in this study provided sufficient evidence that the taxonomic status of the members of Clade I need to be revised. Interestingly, all members of the clade I originated from tropical and sub-tropical habitats while members of the Cylindrospermum sensu stricto clade have been reported from temperate conditions. Previous studies had also indicated the possibility of the formation of tropical and subtropical Cylindrospermum-like genera and thus, this comes across as a much-awaited study to resolve the taxonomic complexities around the genus Cylindrospermum. Based on the results obtained in this study and the trends observed in the earlier studies, we describe a novel Cylindrospermum-like genus Johanseniella gen. nov., with the type species Johanseniella tripurensis sp. nov. in accordance with the International Code of Nomenclature of algae, fungi and plants.

Phototrophic and fungal communities inhabiting the Roman cryptoporticus of the national museum Machado de Castro (UNESCO site, Coimbra, Portugal)

Caves are oligotrophic environments, characterized by constant temperatures, high humidity and low natural light. However, microbial shifts can still happen in such environments, especially with the increase in tourist activity and implementation of artificial lights, making caves even more susceptible to environmental changes. As a result, proliferation of phototrophic organisms can increase dramatically, leading to their settlement on stone surfaces, which in turn facilitates the development of heterotrophic organisms, such as fungi and bacteria. The Roman Cryptoporticus of the National Museum Machado de Castro, erected by the Romans in the 1st or second century, is one of the most emblematic buildings in the city of Coimbra. However, the majority of the rooms that constitute this monument show signs of biodeterioration by microalgae and cyanobacteria as well as of fungi. The aim of this study was to characterize the phototrophic and fungal communities at this site, employing culture-dependent and-independent methodologies. Culture-dependent results showed that the phototrophic communities were mainly composed of green microalgae, whereas the culture-independent showed that cyanobacteria were the most dominant. As to the fungal communities, both approaches identified various entomopathogenic fungal species. In addition, the culture-independent analysis also allowed to verify the presence of animal reads, suggesting the hypothesis that animal vectored dispersion can play an important role in the development of fungi at this environment.