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

Abstract

The cyanobacterial genus Nostoc is an important contributor to carbon and nitrogen bioavailability in terrestrial ecosystems and a frequent partner in symbiotic relationships with non-diazotrophic organisms. However, since this currently is a polyphyletic genus, the diversity of Nostoc -like cyanobacteria is considerably underestimated at this moment. While reviewing the phylogenetic placement of previously isolated Nostoc -like cyanobacteria originating from Brazilian Amazon, Caatinga and Atlantic forest samples, we detected 17 strains isolated from soil, freshwater, rock and tree surfaces presenting patterns that diverged significantly from related strains when ecological, morphological, molecular and genomic traits were also considered. These observations led to the identification of the evaluated strains as representative of three novel nostocacean genera and species: Amazonocrinis nigriterrae gen. nov., sp. nov.; Atlanticothrix silvestris gen. nov., sp. nov.; and Dendronalium phyllosphericum gen. nov., sp. nov., which are herein described according to the rules of the International Code of Nomenclature for algae, fungi and plants. This finding highlights the great importance of tropical and equatorial South American ecosystems for harbouring an unknown microbial diversity in the face of the anthropogenic threats with which they increasingly struggle.

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

“…It also can lead to ensuing confusion in future studies of the same or related taxa. In our case, we, unfortunately, ran into not one, but two studies [17, 33] which were almost contemporary and incidentally had the same shortcomings.…”

“…With an aim to fully characterize strain 19C-PS T , sequencing of the 16S rRNA gene and the 16S-23S ITS region was performed and the resulting phylogenetic trees were analysed. It is well known from our previous experiences and that of others [5,[7][8][9][10][11][12][13][14][15][16][17]32] that these two markers have proven to be effective in understanding the taxonomic complexities of the genus Nostoc and its morphotypic genera. The 16S rRNA gene tree in our phylogeny was reconstructed using 270 operational taxonomic units (OTUs) from Nostocales and was found to be almost in coherence with the above-mentioned studies and the genera Mojavia, Desmonostoc, Halotia, Aliinostoc, Komarekiella, Compactonostoc, Desikacharya, Purpureonostoc, Violetonostoc, Parakomarekiella, Pseudoaliinostoc, Atlanticothrix and Dendronalium occupied distinct monophyletic positions (Fig.…”

“…Notably, Alvarenga et al [17] in their study had also performed phylogenomic analysis; however, in the phylogenomic tree represented in their study, the order Nostocales remained underrepresented due to the limited number of available genomes in the public database. Furthermore, out of the five strains identified as A. nigriterrae the authors had sequenced the whole genome of CENA67 T which clusters in clade I of this study.…”

“…With the establishment of the Nostoc sensu stricto clade [7], various other related taxa have come into existence, with many novel generic entities new to science being described. They include Mojavia [7], Desmonostoc [8], Halotia [9], Aliinostoc [5], Komarekiella [10], Compactonostoc [11], Desikacharya [12], Violetonostoc [13], Purpureonostoc [14], Parakomarekiella [15], Pseudoaliinostoc [16], Amazonocrinis, Atlanticothrix and Dendronalium [17]. All of the above-described taxa have proven the genus Nostoc to be highly heterogenic and polyphyletic based on its 16S rRNA gene phylogeny.…”

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

“…The 16S rRNA sequences from all strains were included together with 65 reference sequences from public databases to construct a phylogeny. The dataset also included recently described taxa in the order Nostocales, including Amazonocrinis nigriterrae, Dendronalium phyllosphaericum, Constrictifilum karadense , and Atlanticothrix silvestris (Alvarenga et al, 2021 ; Chavadar et al, 2021 ). Phylogenetic trees obtained from ML and BI analyses had similar topologies at the terminal clades.…”