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.

Treatment of the Allura Red food colorant contaminated water by a novel cyanobacterium Desertifilum tharense

The biosorption properties of a newly isolated and identified cyanobacterium called Desertifilum tharense were investigated in the current study. Following morphological and molecular identification (16S rRNA sequencing analysis), the food colorant removal potential of this new isolate was determined. Moreover, the isotherm, kinetic, and thermodynamic studies were performed, and also the biosorbent characterization was studied after and before colorant biosorption with Fourier transform infrared and scanning electron microscopy analysis. Additionally, the changes in chlorophyll content of the biosorbent were examined after and before colorant treatment. The newly isolated cyanobacterial biosorbent removed 97% of Allura Red food colorant/dye at 1,500 mg L^-1 initial dye concentration successfully at optimal conditions. Langmuir isotherm and pseudo-second-order kinetic models were fitted with the biosorption of the dye. The D-R model showed that the biosorption process occurred physically. The chlorophyll-a content of the biosorbent was negatively affected by the biosorption. The newly isolated and identified cyanobacterium seems to be a successful candidate for use to treat highly dye concentrated wastewaters.

Coleofasciculaceae, a Monophyletic Home for the Microcoleus steenstrupii Complex and Other Desiccation-tolerant Filamentous Cyanobacteria

Cyanobacteria classified as Microcoleus steenstrupii play a significant role as pioneers of biological soil crusts (biocrusts), but this taxon is recognized to constitute a diverse complex of strains and field populations. With the aim of clarifying its systematics, we conducted a polyphasic characterization of this and allied taxa. A 16S ribosomal gene meta-analysis of published environmental sequences showed that the complex encompasses a variety of well supported genus-level clades with clade-specific environmental preferences, indicating significant niche differentiation. Fifteen strains in the M. steenstrupii complex were selected as representative of naturally occurring clades and studied using 16S rRNA gene phylogeny, morphology, and niche delineation with respect to temperature and rainfall. Bayesian phylogenetic reconstructions within a comprehensive, curated database of long 16S rRNA cyanobacterial sequences (1,000 base pairs or more) showed that they all belonged in a monophyletic, family-level clade (91.4% similarity) that included some other known genera of desiccation-resistant, largely terrestrial, filamentous, nonheterocystous cyanobacteria, including Coleofasciculus, the type genus for the family Coleofasciculaceae. To accommodate this biodiversity, we redescribe the Coleofasciculaceae, now composed of 11 genera, among which six are newly described herein (Funiculus, Parifilum, Arizonema, Crassifilum, Crustifilum, and Allocoleopsis), and five were previously recognized (Porphyrosiphon, Coleofasciculus, Pycnacronema, Potamolinea, and Wilmottia). We provide an evaluation of their respective niches and global distributions within biocrusts based on published molecular data. This new systematics treatment should help simplify and improve our understanding of the biology of terrestrial cyanobacteria.

Whole-genome characterization and comparative genomics of a novel freshwater cyanobacteria species: Pseudanabaena punensis

Cyanobacteria are emerging as a potential source of novel, beneficial bioactive compounds. However, some cyanobacteria species can harm water quality and public health through the production of toxins. Therefore, surveying the occurrence and generating genomic resources of cyanobacteria producing harmful compounds could help develop the control methods necessary to manage their growth and limit the release contaminants into the water bodies. Here, we describe a novel strain, Pseudanabaena punensis isolated from the open ends of pipelines supplying freshwater. This isolate was characterized morphologically, biochemically and by whole-genome sequence analysis. We also provide genomic information for P. punensis to help understand and highlight the features unique to this isolate. Morphological and genetic (analysis using 16S rRNA and rbcL genes) data were used to assign this novel strain to phylogenetic and taxonomic groups. The isolate was identified as a filamentous and non-heterocystous cyanobacteria. Based on morphological and 16S rRNA phylogeny, this isolate shares characteristics with the Pseudanabaenaceae family, but remains distinct from well-characterized species suggesting its polyphyletic assemblage. The whole-genome sequence analysis suggests greater genomic and phenotypic plasticity. Genome-wide sequence and comparative genomic analyses, comparing against several closely related species, revealed diverse and important genes associated with synthesizing bioactive compounds, multi-drug resistance pathway, heavy metal resistance, and virulence factors. This isolate also produces several important fatty acids with potential industrial applications. The observations described in this study emphasize both industrial applications and risks associated with the freshwater contamination, and therefore genomic resources provided in this study offer an opportunity for further investigations.

Characterization of Macroscopic Colony-Forming Filamentous Cyanobacteria from Okinawan Coasts as Potential Sources of Bioactive Compounds

Marine macroscopic colony-forming filamentous (MMCFF) cyanobacteria are considered as prolific producers of bioactive compounds. Thus, knowledge of the diversity of MMCFF cyanobacteria as related to bioactive compound production has become very important. However, basic taxonomic studies of MMCFF cyanobacteria are lacking. Many cyanobacterial taxa are still misidentified or undescribed. In this study, a total of 32 cyanobacterial colonies from nine coastal regions of Okinawa Prefecture were investigated for a diversity assessment. A polyphasic approach including morphological and molecular studies based on 16S rRNA gene sequences was performed to characterize Okinawan MMCFF cyanobacteria. Both morphological and molecular phylogenetic results showed that MMCFF cyanobacteria from Okinawan coasts are very diverse. We found morphotypes of Lyngbya-like, Phormidium-like, and Leptolyngbya-like groups among Okinawan cyanobacterial samples. Genetically, samples were distributed in various clades in the phylogenetic tree, including within Moorena, Okeania, Caldora, Neolyngbya, Dapis, as well as several unknown clades. In addition, cytotoxic activities of three samples from Kiyan coast were tested against HeLa cells. All three crude extracts of these samples showed strong cytotoxic activity with IC₅₀ < 1 μg/ml.

Dereplication of Natural Products with Antimicrobial and Anticancer Activity from Brazilian Cyanobacteria

Cyanobacteria are photosynthetic organisms that produce a large diversity of natural products with interesting bioactivities for biotechnological and pharmaceutical applications. Cyanobacterial extracts exhibit toxicity towards other microorganisms and cancer cells and, therefore, represent a source of potentially novel natural products for drug discovery. We tested 62 cyanobacterial strains isolated from various Brazilian biomes for antileukemic and antimicrobial activities. Extracts from 39 strains induced selective apoptosis in acute myeloid leukemia (AML) cancer cell lines. Five of these extracts also exhibited antifungal and antibacterial activities. Chemical and dereplication analyses revealed the production of nine known natural products. Natural products possibly responsible for the observed bioactivities and five unknown, chemically related chlorinated compounds present only in Brazilian cyanobacteria were illustrated in a molecular network. Our results provide new information on the vast biosynthetic potential of cyanobacteria isolated from Brazilian environments.

Polyphasic approach using multilocus analyses supports the establishment of the new aerophytic cyanobacterial genus Pycnacronema (Coleofasciculaceae, Oscillatoriales)

A new Phormidium-like genus was found during an investigation of Oscillatoriales diversity in Brazil. Eight aerophytic populations from south and southeastern regions were isolated in monospecific cultures and submitted to polyphasic evaluation. The populations presented homogeneous morphology with straight trichomes, not attenuated, and apical cell with thickened cell wall. Phylogenetic analyses based on 16S rRNA gene sequences showed that these populations, plus the Brazilian strain Phomidium sp. B-Tom from GenBank, formed a highly supported and distinctive clade, which corresponds to the new genus Pycnacronema, comprising six new species: P. brasiliensis (type species), P. arboriculum, P. conicum, P. marmoreum, P. rubrum, and P. savannensis. These results were confirmed and supported by rpoC1 and rbcL genes evaluated independently and by the concatenated analysis of 16S rRNA, rpoC1 and rbcL genes (for all species but P. savannensis). Secondary structures of the D1-D1', box-B, and V3 regions of the internal transcribed spacer were informative at specific level, being conserved in P. brasiliensis and variable among the other strains, also confirming the phylogenetic analyses. The generic name and specific epithets of the new taxa are proposed under the provisions of the International Code of Nomenclature of algae, fungi, and plants.

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.

Kryptousia macronema gen. nov., sp. nov. and Kryptousia microlepis sp. nov., nostocalean cyanobacteria isolated from phyllospheres

Tropical ecosystems worldwide host very diverse microbial communities, but are increasingly threatened by deforestation and climate change. Thus, characterization of biodiversity in these environments, and especially of microbial communities that show unique adaptations to their habitats, is a very urgent matter. Information about representatives of the phylum Cyanobacteria in tropical environments is scarce, even though they are fundamental primary producers that help other microbes to thrive in nutrient-depleted habitats, including phyllospheres. In order to increase our knowledge of cyanobacterial diversity, a study was conducted to characterize isolates from Avicennia schaueriana and Merostachys neesii leaves collected at a mangrove and an Atlantic forest reserve located at the littoral of São Paulo state, south-east Brazil. The morphological, ultrastructural, phylogenetic, molecular and ecological features of the strains led to the recognition of the new genus Kryptousia, comprising two new species, Kryptousiamacronema gen. nov., sp. nov. and Kryptousiamicrolepis sp. nov., described here according to the International Code of Nomenclature for algae, fungi and plants. The new genus and species were classified in the nostocalean family Tolypotrichaceae. This finding advances knowledge on the microbial diversity of South American ecosystems and sheds further light on the systematics of cyanobacteria.

Phylogenetic insights into the diversity of homocytous cyanobacteria from Amazonian rivers

The Amazon Rainforest holds great tropical biodiversity, mainly because of its favourable climatic conditions. The high temperatures, luminosity and humidity coupled with the nutritional simplicity of cyanobacteria allow undiscovered diversity to flourish within this group of microorganisms. Some efforts to reveal this diversity have been attempted; however, most were focused on the microscopic observation of environmental samples without any genetic information. Very few studies focusing on morphological, ecological and molecular criteria have been conducted, and none have been devoted to homocytous cyanobacteria forms in Amazonia region. Therefore, the genetic relationships amongst strains retrieved from this ecosystem with regard to other environments from Brazil and the world have not been tested and, consequently, the Amazonian strains would naturally be assumed as novel to science. To examine these relationships, cultured homocytous cyanobacteria isolated from two Amazonian rivers (Amazonas and Solimões) were evaluated using a phylogenetic perspective, considering the 16S rRNA gene sequence. A total of eleven homocytous cyanobacterial strains were isolated. Morphologically, they were identified as Pseudanabaena, Leptolyngbya, Planktothrix and Phormidium, but genetically they were included in the typical clusters of Planktothrix, Pseudanabaena, Cephalothrix, Pantanalinema and Alkalinema. These three latter genera have been detected in other Brazilian ecosystems only (Pantanal, Atlantic Rainforest and Pampa), while those remaining have been extensively found in many parts of the world. The data provided here indicate that Amazonian rivers support a homocytous cyanobacterial diversity previously reported from other geographical and ecological environments.