Li, Renhui

As our comprehension of cyanobacterial classification in diverse ecosystems broadens, it becomes essential to explore the biodiversity of lesser-known areas for a thorough understanding of both global and local diversity. This research, which is part of a larger investigation into soil biocrust algae diversity in the Sanyang Wetland located in Zhejiang Province, China, introduces a novel taxon of non-heterocystous filamentous cyanobacteria employing a polyphasic approach for cyanobacterial classification, integrating morphological, molecular, ecological, and biogeographical considerations. The findings from morphological analysis, 16S rRNA gene sequencing, and the identification of the 16S-23S ITS rRNA region have led to the discovery of a new genus, Paludothrix, which is categorized within the family Coleofasciculaceae. The proposed generic name and specific epithet of these new taxa adhere completely to the guidelines established by the International Code of Nomenclature for algae, fungi, and plants. The modern taxonomic system of cyanobacteria is constantly being updated and improved. The description of new taxa using the polyphasic approach can enrich the relevant knowledge in the field of cyanobacteria classification. The results of this study will increase our understanding of terrestrial cyanobacteria within wetland environments.

AbstractCyanobacterial mats supplanting coral and spreading coral diseases in tropical reefs, intensified by environmental shifts caused by human‐induced pressures, nutrient enrichment, and global climate change, pose grave risks to the survival of coral ecosystems. In this study, we characterized Okeanomitos corallinicola gen. and sp. nov., a newly discovered toxic marine heterocyte‐forming cyanobacterium isolated from a coral reef ecosystem of the South China Sea. Phylogenetic analysis, based on the 16S rRNA gene and the secondary structure of the 16S–23S rRNA intergenic region, placed this species in a clade distinct from closely related genera, that is, Sphaerospermopsis stricto sensu, Raphidiopsis, and Amphiheterocytum. The O. corallinicola is a marine benthic species lacking gas vesicles, distinguishing it from other members of the Aphanizomenonaceae family. The genome of O. corallinicola is large and exhibits diverse functional capabilities, potentially contributing to the resilience and adaptability of coral reef ecosystems. In vitro assays revealed that O. corallinicola demonstrates notable cytotoxic activity against various cancer cell lines, suggesting its potential as a source of novel anticancer compounds. Furthermore, the identification of residual saxitoxin biosynthesis function in the genome of O. corallinicola, a marine cyanobacteria, supports the theory that saxitoxin genes in cyanobacteria and dinoflagellates may have been horizontally transferred between them or may have originated from a shared ancestor. Overall, the identification and characterization of O. corallinicola provides valuable contributions to cyanobacterial taxonomy, offering novel perspectives on complex interactions within coral reef ecosystems.