Trichodesmium

Abstract Tri.cho.des'mi.um. Gr. fem. n. thrix , trichos , hair; Gr. masc. n. desmos , bond; N.L. neut. n. Trichodesmium , bonded filaments. Filamentous, marine cyanobacteria that divide exclusively by binary fission in one plane. Trichomes of different species or strains range from 5 to 35 μm in diameter. Isolates have cells that range from barrel to disk shaped; constrictions at cross‐walls are shallow. Trichomes can arrange in parallel fascicles or form radiate macroscopic clusters in situ (i.e., colonies), while many strains and natural communities exist as free trichomes. Gliding motility has been observed. Trichodesmium species are often important N 2 ‐fixing constituents of the plankton in tropical to subtropical oceans. Additionally, they can form extensive, ephemeral surface blooms with high cellular abundance under calm sea conditions. Trichodesmium spp. are aerobic, oxygenic phototrophs that fix carbon dioxide using the RuBisCO pathway. Photoheterotrophy has not been demonstrated. N 2 fixation is performed during the daylight hours without heterocysts, and neither hormogonia nor akinetes have been observed. Trichodesmium isolates range from reddish/orange to greenish yellow in color, with absorption peaks for phycourobilin (PUB, 498 nm), phycoerythrobilin (PEB, 545 nm), and/or phycocyanin (PC, 618 nm). All known members contain abundant gas vacuoles, generally dispersed throughout the cells and exceptionally resistant to collapse, even at hydrostatic pressures of 12–27 bars. DNA G + C content (mol%) = 33–34. G enome of type species : Trichodesmium erythraeum IMS101 (Walworth et al., 2015). Type species : Trichodesmium erythraeum Ehrenberg ex Gomont 1892. Taxonomic and Nomenclature Notes According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus Trichodesmium is: correct name (last update, February 2025) * . LPSN classification: Bacteria / Bacillati / Cyanobacteriota / Cyanophyceae / Oscillatoriales / Microcoleaceae / Trichodesmium The genus Trichodesmium can also be recovered in the Genome Taxonomy Database (GTDB) as g__Trichodesmium (version v220) ** . GTDB classification: d__Bacteria / p__Cyanobacteriota / c__Cyanobacteriia / o__Cyanobacteriales / f__Microcoleaceae / g__Trichodesmium * Meier‐Kolthoff et al. ( 2022 ). Nucleic Acids Res , 50 , D801 – D807 ; DOI: 10.1093/nar/gkab902 ** Parks et al. ( 2022 ). Nucleic Acids Res , 50 , D785 – D794 ; DOI: