Isosphaera

Abstract I.so.sphae'ra. Gr. masc. adj. isos equal; L. fem. n. sphaera ball or sphere; N.L. fem. n. Isosphaera sphere of equal size. Planctomycetes / Planctomycetia / Isosphaerales / Isosphaeraceae / Isosphaera The genus Isosphaera is represented by planctomycetes with spherical cells, 2.0–2.5 μm in diameter, which are assembled in chains of indefinite length, often over 100 cells. Cell division is by budding, intercalary or terminal. No branching occurs. Gas vesicles are usually present in all cells, mostly in one cluster (gas vacuole or “pseudovacuole”). Resting cells are not known. The Gram‐stain is variable. Cells are motile by means of gliding; pili are present, but flagella are absent. Cells are capable of phototaxis on a solid substrate. Members of the genus are strictly aerobic bacteria that grow within the temperature range ∼40–55°C in culture. The optimal pH range is 7.8–8.8. The type and the only currently described species is Isosphaera pallida . This genus is a member of the phylum Planctomycetes , class Planctomycetia , order Isosphaerales , and family Isosphaeraceae . The main habitats are hot springs. DNA G + C content ( mol %): 62.4 (genome sequence). Type species : Isosphaera pallida Giovannoni et al. 1987b, VL54 (basonyms: Isocystis pallida Woronichin 1927 – as a cyanobacterium; Torulopsidosira pallida Geitler 1963 – as a yeast).