Cylindrospermum

Cylindrospermum is a genus of filamentous cyanobacteria in the order Nostocales. Members form colonies composed of uniseriate trichomes—filaments of cylindrical cells—that are typically embedded in a mucilaginous sheath. The trichomes are often heterocystous, containing specialized nitrogen-fixing cells at intervals, which enables atmospheric nitrogen fixation under suitable anaerobic conditions.

Habitat and distribution: Cylindrospermum species are commonly found in freshwater environments such as ponds, streams, and ditches, and can also occur on moist soils and rocky substrates. They are reported from tropical and subtropical regions and may form surface blooms or crusts on submerged or damp surfaces.

Ecology and physiology: As nitrogen fixers, Cylindrospermum contribute to nitrogen input in nutrient-poor aquatic systems. Growth is influenced by light, temperature, and nutrient availability, with blooms typically promoted by elevated phosphorus and nitrogen levels and favorable water chemistry. The extent of toxin production varies among species and is a subject of ongoing study; some Nostocales are known to produce cyanotoxins, while toxin production in Cylindrospermum is not uniformly documented.

Reproduction and development: Propagation occurs mainly through fragmentation of trichomes, which can give rise to new colonies. Certain species may form hormogonia, short reproductive filaments that disperse to establish new growth, and some may produce resting cells such as akinetes to endure adverse conditions.

Taxonomic notes: Cylindrospermum has historically been placed among heterocystous, filamentous cyanobacteria within Nostocales. Advances in molecular phylogenetics have refined cyanobacterial taxonomy, but Cylindrospermum is generally recognized as a Nostocales genus characterized by mucilaginous colonies and heterocystous filaments.