Expanding species diversity in the monotypic genera Thalassoporum and Tumidithrix (Pseudanabaenales, Cyanobacteriota) with the description of Thalassoporum mexicanum sp. nov. and Tumidithrix helvetica sp. nov.
Journal
International Journal of Systematic and Evolutionary Microbiology
Date Issued
2025-08-19
Author(s)
Saraf, Aniket
Aleksovski, Boris
Blondet, Eddy
Krstić, Svetislav
Criscuolo, Alexis
Gugger, Muriel
DOI
https://doi.org/10.1099/ijsem.0.006869
Abstract
The taxonomic identity of two well-documented
pseudanabaenalean strains, Pseudanabaena sp. PCC 7367T and Pseudanabaena
sp. PCC 7403T, isolated from the samples collected from the surface of a snail shell in an intertidal zone and sphagnum bog,
respectively, was reassessed using a polyphasic approach. The results from the morphological, phylogenetic, ITS rRNA and
genomic analyses confirmed that PCC 7367T (=BACA0810T) and PCC 7403T (=BACA0811T) represent novel species of the monotypic
pseudanabaenalean genera Thalassoporum and Tumidithrix, respectively, for which we propose the names Thalassoporum
mexicanum sp. nov. and Tumidithrix helvetica sp. nov. in accordance with the International Code of Nomenclature of Prokaryotes.
The analysis of the 16S-23S
ITS rRNA region, a widely used genetic marker for the delineation of closely related species, effectively
distinguished the Thalassoporum species. However, the closely related species within Tumidithrix could not be demarcated
using the currently accepted nucleotide dissimilarity cutoff for species delineation but were clearly distinguished through
genomic analyses. Accordingly, a revised ITS rRNA nucleotide dissimilarity cutoff is proposed for species delineation within the
genus Tumidithrix. Furthermore, genomic investigations revealed that the predicted biosynthetic gene clusters in the genome
assemblies of PCC 7367T and PCC 7403T were not associated with any known natural products.
pseudanabaenalean strains, Pseudanabaena sp. PCC 7367T and Pseudanabaena
sp. PCC 7403T, isolated from the samples collected from the surface of a snail shell in an intertidal zone and sphagnum bog,
respectively, was reassessed using a polyphasic approach. The results from the morphological, phylogenetic, ITS rRNA and
genomic analyses confirmed that PCC 7367T (=BACA0810T) and PCC 7403T (=BACA0811T) represent novel species of the monotypic
pseudanabaenalean genera Thalassoporum and Tumidithrix, respectively, for which we propose the names Thalassoporum
mexicanum sp. nov. and Tumidithrix helvetica sp. nov. in accordance with the International Code of Nomenclature of Prokaryotes.
The analysis of the 16S-23S
ITS rRNA region, a widely used genetic marker for the delineation of closely related species, effectively
distinguished the Thalassoporum species. However, the closely related species within Tumidithrix could not be demarcated
using the currently accepted nucleotide dissimilarity cutoff for species delineation but were clearly distinguished through
genomic analyses. Accordingly, a revised ITS rRNA nucleotide dissimilarity cutoff is proposed for species delineation within the
genus Tumidithrix. Furthermore, genomic investigations revealed that the predicted biosynthetic gene clusters in the genome
assemblies of PCC 7367T and PCC 7403T were not associated with any known natural products.