Isolation and Growth of Cyanobacteria from Marine and Hypersaline Environments
In principle, the isolation and purification of cyanobacteria from saline environments does not differ from that for other groups of cyanobacteria (see this Handbook, Chapter 8 for general discussion and Table 1 in this chapter for specific media for mari
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Isolation and Growth of Cyanobacteria from Marine and Hypersaline Environments JOHN B. WATERBURY and ROGER Y. STANIER
In principle, the isolation and purification of cyanobacteria from saline environments does not differ from that for other groups of cyanobacteria (see this Handbook, Chapter 8 for general discussion and Table 1 in this chapter for specific media for marine and halophilic forms). In this chapter, the cyanobacteria of marine and hypersaline environments will be discussed separately; the physiological properties which distinguish these cyanobacteria from others and the range of taxonomic diversity encountered in saline environments will be indicated.
Marine Cyanobacteria Cyanobacteria have an ancient marine history which cart be traced back almost three billion years in the fossil record (Brock, 1973). During the Precambrian, they were probably the dominant photosynthetic organisms in the world's oceans, being especially prevalent in the intertidal zone and in shallow tropical seas. Today they are less conspicuous but are still an important component of marine habitats throughout the world. Cyanobacteria isolated from marine environments can be divided into two physiological categories based on their major ionic requirements for growth. Some isolates are halotolerant and grow indifferently on a medium with either a seawater or freshwater base. Others have obligate requirements for elevated concentrations of sodium, magnesium, calcium, and chloride (Stanier and Cohen-Bazire, 1977; Waterbury, 1976) that preclude their growth in freshwater media (e.g., BG-ll) even when supplemented with 3% wtlvol sodium chloride. In practice, both categories can be cultivated in media with a natural or artificial seawater base (Table 1). However, only strains with obligately elevated ionic requirements can be construed as intrinsically marine. Halotolerant marine isolates are not necessarily indigenous marine cyanobacteria. Such isolates may represent terrestrial or freshwater cyanobacteria that have been reintroduced into the marine environment. Marine cyanobacteria are found in all the world's oceans but are most abundant in warmer temperate M. P. Starr et al. (eds.), The Prokaryotes © Springer-Verlag Berlin Heidelberg 1981
and tropical regions. Their taxonomic diversity does not differ markedly from that of cyanobacteria found in terrestrial and freshwater habitats. Representatives from each of the five major taxonomic sections (see this Handbook, Chapter 12) have been isolated from marine sources. However, particular marine habitats (e.g., intertidal and subtidal zones, coral reefs, salt marshes, and the open ocean) often harbor a restricted and characteristic diversity of forms which may differ markedly from season to season and between different geographical locations (Fogg, 1973; Fogg et aI., 1973). The intertidal and subtidal zones contain a diverse assemblage of cyanobacteria that are typically found attached to solid substrates such as rocks, mollusk shells, pieces of wood, and eukaryotic macroalgae. Pleuroc
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