Crocosphaera

Abstract

Cro.co.sphae'ra. Gr. xxxxx n krokos , the crocus, orange‐colored; Gr. fem. n. sphaera , a ball or sphere; N.L. fem. n. Crococsphaera , an orange ball or sphere, M.L. fem. n., Crocosphaera , an orange ball due to autofluorescence of high urobilin phycoerythrin. Cyanobacteria / Subsection I / Incertae Sedis / Crocosphaera Coccoid, pigmented nonmotile cyanobacterial cells found in open ocean plankton that range in diameter from 2 to 6 μm, although larger cells have been reported in the environment. Cells occur singly or in small clusters and reproduce in one plane. Several known strains vary primarily in size, are capable of extracellular polysaccharide (EPS) synthesis, and comprise two phenotypic groups. Aerobic oxygenic phototrophs that fix carbon dioxide using the ribulose‐1,5‐bisphosphate carboxylase/oxygenase (RuBisCO) pathway. Can grow with atmospheric nitrogen (N 2 ) as the sole nitrogen source with an oxygen‐sensitive nitrogenase. Fix N 2 primarily in the dark period of a light–dark cycle under atmospheric concentrations of oxygen. Evolve molecular hydrogen (H 2 ) and contain an uptake hydrogenase. In addition to chlorophylls a and b possess phycoerythrin with high phycourobilin content. Gas vacuoles are absent. Capable of secondary metabolite (possible toxin) production since they possess polyketide synthesis (PKS) and nonribosomal polyketide synthesis (NRPS) genes. Synthesize trehalose. Are ecologically important as N 2 ‐fixers but are limited to the tropical oceans or seasonally in the subtropics due to restricted temperature range permitting growth. DNA G + C content (mol%) : 30.6–31.0 ( T m ) (WH8501 and WH8502); 37.1–37.7 (genome sequences). Type species : Crocosphaera watsonii Mareš et al. 2019.

Microalgal and Nitrogen-Fixing Bacterial Consortia: From Interaction to Biotechnological Potential

“…The unicellular cyanobacteria Crocosphaera spp. [104] appears to be highly favored for this type of endosymbiotic interaction. In fact, permanent endosymbionts that are closely related to the Crocosphaera genus, particularly Crocosphaera subtropica, are found in various microalgae including the diatoms Epithemia spp.…”

Quantification of gene copy numbers is valuable in marine microbial ecology: A comment to Meiler et al. (2022)

“…Trichodesmium spp. are a group of filamentous, cyanobacteria that do not form specialized N 2 ‐fixing heterocyst cells (Zehr et al 2023). Trichodesmium species vary greatly in size (6–16 μ m in width and 4–23 μ m long across very diverse species; Hynes et al 2012), and other characteristics (Webb et al 2009, Zehr et al 2023; Hynes et al 2012), but only a few species are typically abundant and found in wide areas of the ocean.…”

“…are a group of filamentous, cyanobacteria that do not form specialized N 2 ‐fixing heterocyst cells (Zehr et al 2023). Trichodesmium species vary greatly in size (6–16 μ m in width and 4–23 μ m long across very diverse species; Hynes et al 2012), and other characteristics (Webb et al 2009, Zehr et al 2023; Hynes et al 2012), but only a few species are typically abundant and found in wide areas of the ocean. Filamentous heterocyst‐forming N 2 ‐fixing cyanobacteria are associated with a number of genera of diatoms that also range in size and physical location of the symbiont, but also the number of filaments per diatom, the number of heterocysts per filament, and the degree of aggregation or chain formation (Caputo et al 2019).…”

“…There are coastal and open ocean UCYN‐A ecotypes that vary in size by at least a factor of 5 (Turk‐Kubo et al 2021). Crocosphaera watsonii is a marine planktonic species that is comprised of a number of very closely related strains (Webb et al 2009; Zehr et al 2023), include both free‐living and symbiotic forms, but vary in size, physiology and aggregation. C. watsonii natural populations are comprised of large and small forms and aggregates (Zehr et al 2023).…”

“…Crocosphaera watsonii is a marine planktonic species that is comprised of a number of very closely related strains (Webb et al 2009; Zehr et al 2023), include both free‐living and symbiotic forms, but vary in size, physiology and aggregation. C. watsonii natural populations are comprised of large and small forms and aggregates (Zehr et al 2023). Most common is the small form (Webb et al 2009; Bench et al 2016).…”