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  1. 1. CH.(6) By: Raghdah A. Malibari 2012 - 2013
  2. 2. Heterocyte and akinete – producing cyanobacteria
  3. 3. Nostoc Habitat Primarily occurs in terrestrial habitat. Association with fungi in lichens and with some bryophytes and vascular plants. Moist rocks and cliffs.  Alkaline soil. In wet meadows. At the edges of shallow lakes. Cellular structure Bent or naked filaments of round cells are held in a firm mucilaginous matrix to form colonies. The sheaths colored by yellow, brown or black. Transiently motile hermogonia are produced these typically have heterocytes at the ends. Characteristics Nostoc is frequently abundant in flooded rice paddies where it contributes to the fertilization of some 2 million hectares.
  4. 4. Anabena Habitat Primarily planktonic in fresh waters and marine waters such as the Baltic Sea some forms can be nuisance bloom formers and toxin producers. Cellular structure Consist of filaments of spherical cells resembling in a mucilaginous matrix . Molecular phylogenetic analyses indicate that Anabaena is not monophyletic group separated into multiple classes.
  5. 5. Aphanizomenon Habitat Occurs in the Baltic Sea and in eutrophic inland water. Cellular structure Consist of distinctive aggregations of filaments (so large as to be visible). Molecular phylogenetic within Anabaena as the Aphanizomenon.  May not be monophyletic. Characteristics Aphanizomenon that which makes itself invisible. Large blooms may form in the Baltic Sea and in eutrophic inland waters.
  6. 6. Cylindrospermum Habitat Occurs in freshwaters including soft, acid lakes. Forming dark green patches on submerged vegetation and on moist soil. Cellular structure Filaments of vegetative cells ( square or rectangular cells).  Heterocyte at one end are enclosed in loose mucilage.  A large ,highly or nemented akinete may develop from the lowermost vegetative cell.
  7. 7. Cylindrospermopsis Habitat Plaktonic bloom-former in eutrophic temperate.  Tropical freshwater around the world. Cellular structure Rectangular cells occur in linear or coiled filments having a basal heterocyte. Akinetes may form basally.  If akinetes are not present , correct species identification may be difficult. Characteristics  Important nitrogen – fixing. C.Raciborskii this species produces the hepatotoxin cylindrospermopsin caused poisoning.
  8. 8. Tolypothrix Habitat Plaktonic. Entangled among submergent vegetation in freshwater lakes (soft or acidic water ). Cellular structure Filaments are enclosed in a sheath of variable consistency .  Highly false branched usually at a heterocyte ( single false and sometimes double false branches occur). Characteristics The frequency of false branching gives these algae a woolly appearance.
  9. 9. Scytonema Habitat Forms dark tufted mats in masses of other algae.  Vegetation in lakes.  On terrestrial surfaces ( stones , wood and soil ). Cellular structure Often double false branches occur , this result has been interrupted by death of a cell .  Less commonly by heterocyte differentiation.  Heterocyte wall may be darkly pigmented.  Sheath is tough and sometimes clearly layered ( colored brown or orange ). Characteristics It is a phycobiont in several orders of lichen.
  10. 10. Gloeotrichia Habitat Occurs in freshwater habitat attached to submerged substrate. Cellular structure Akinetes occur adjacent to basal heterocytes ( sometimes appearing in chains). Characteristics Gloeotrichia colonies often detach from substrate , becoming planktonic.  Growths can reach bloom properations.
  11. 11. True – branching cyanobacteria
  12. 12. Stigonema Habitat Moist rocks.  Soil. Some species are aquatic , attached to submerged wood or other algae.  Form tufted mats or cushions on submerged portions of lake macrophytes. Cellular structure The filaments are more than one cell in width as (multiseriate or pluriseriate).  Are true-branched. Characteristics  The primary phycobiont in certain lichens and is associated with boreal mosses.  Contributes to nitrogen availability.
  13. 13. Raghdah A. Malibari

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