Morphological and ultrastructural variability of planktonic Cyanophyceae in relation to seasonal periodicity III. Gomphosphaeria naegeliana

Abstract

Cells of Gomphosphaeria naegeliana are ultrastructurally more complex than most species of Chroococcales. In addition to the usual inclusions (ribosome-filled nucleoplasm, peripheral thylakoids, glycogen, lipid, polyphosphate, cyanophycin, carboxysomes and gas vesicles), cells accumulate poly-β-hydroxybutyric acid (PHB). This compound is common in bacteria but previously known from only three other cyanophytes, Chlorogloea fritschii, Microcystis aeruginosa and Spirulina platensis. Affinities between Gomphosphaeria, Microcystis and Gramnegative bacteria are further emphasized by presence of an additional “outer layer” external to the outer-wall component.