Home / Cyanobacteria / Filaments / Unbranched / Untapered / No_heterocysts / Visible_sheath / Phormidum

 

 

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Name derivation:

 

Phorm– (Gr.) φορμός, basket, mat (Oren 2011) - a reference to the mat of intertwined filaments.

 

 

Classification:

 

Phormidium  Kützing ex Gomont  1892;  172 of 652 species descriptions are currently accepted taxonomically (Guiry and Guiry 2013).

Order Oscillatoriales;  Family Phormidiaceae

 

Morphology:

 

Trichome lacking heterocysts, not tapered, and having a sheath extending beyond the end of the trichomes.

 

Inducible defence against ciliate attacks:

 

Pseudomicrothorax can ingest long trichomes of Oscillatoria.

Filaments of Phormidium sp. have an inducible reaction to attacks by the ciliate.  When a Pseudomicrothorax initiates ingestion from one end of the filament, the trichome retreats inside its sheath leaving an apparently indigestible end to the filament.  If attacked at a non-terminal position along the filament, the trichome fragments and the two shorter trichomes produced move in opposite directions away from the area (Fialkowska and Pajdak-Stos  1997).

Ingestion velocity of Oscillatoria formosa trichomes has been measured at >15 μm s-1 (Hausmann 1980).   See videos 1 minute and 10 minute.

 

 

Similar genera:

 

Pseudophormidium is not separated in Phycokey.

 

 

Competition with Microcystis:

 

Under nutrient-limited growth conditions Phormidium outcompetes Microcystis at all N:P supply ratios of 11, 22, 44 and 89 and lower (20 C) temperature, but the reverse happens with at the 11, 22 and 44 supply ratios but higher temperature (25 and 30 C).  Yet at the highest supply ratio of 89 and 25 or 30 C, neither clearly outcompeted the other (Fujimoto et al. 1997).

 

 

Anti-cancer agents:

 

Two of several isolated diacylglycerols (DGDGs) inhibited development of epithelial papillomas in mice (Tokuda et al. 1996).

 

 

Toxicity:

 

Anatoxin-a (Sivonen and Jones 1999).

 

 

Habitat:

 

Filaments form mats on various aquatic substrates (mainly freshwater, some in marine littoral area) and even wet soil.  Some species are extremophiles in hot springs or desert sands and soils.

 

 

 

 

References:

 

Guiry, M.D. and G.M. Guiry  2013.  AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.  http://www.algaebase.org; searched on 15 May 2013.

Fialkowska, E., and A. Pajdak-Stos  1997.  Inducible defence against a ciliate grazer, Pseudomicrothorax dubius, in two strains of Phormidium (cyanobacteria).  Proceedings of the Royal Society of London B 264:937 – 941.

Fujimoto, N., R. Sudo, N. Sugiura and Y. Inamori.  Nutrient-limited growth of Microcystis aeruginosa and Phormidium tenue and competition under various N:P supply ratios and temperatures.  Limnology and Oceanography 42(2):250-256.

Gomont, M.  1892 '1893'.  Monographie des Oscillariées (Nostocacées homocystées).Annales des Sciences Naturelles, Botanique, Series 7 16: 91-264, Plates 1-7.

Hausmann, C.  1980. Nahrungsaufnahme und Verdauung bei dem Ciliaten Pseudomicrothorax dubius. Online video.

Oren, A.  2011.  Naming Cyanophyta/Cyanoacteria – a bacteriologist’s view.  Fottea 11(1):9-16.

Sivonen, K., Jones, G., 1999. Cyanobacterial toxins. In: Chorus, I., Bartram, J. (Eds.), Toxic Cyanobacteria in Water: a Guide Line to Public Health Significance, Monitoring and Management. E&FN Spon, UK, London, pp. 41–111. (online)

Tokuda, H., H. Nishino, H. Shirahashi, N. Murakami, A. Natatsu and J. Sakakibara  1996.  Inhibition of 12-Optetradecanoylphorbol-13 acetate promoted mouse skin papilloma by digalactosyl diacylglycerols from the fresh water cyanobacterium Phormidium tenue.  Cancer Letters 104:91-95.