Enrichment and Isolation Procedures

Halorhodospira species have been isolated from various hypersaline environments, such as salt and soda lakes, from many parts of the world. Alkaline soda lakes show a natural abundance of Ectothiorhodospira species, which can be taken as proof of their successful adaptation to these environments. From such sources, isolation can be achieved by agar dilution series using natural samples without prior enrichment. The tolerance of and dependence on high salinity and alkalinity are strong selective conditions for the enrichment of Halorhodospira species.

A medium based on the mineral composition of the soda lakes of the Wadi Natrun (Jannasch, 1957; Imhoff and Triiper, 1977; Imhoff et al., 1979) is appropriate for the cultivation of all currently known Halorhodospira species. A recipe for this medium containing 20% total salts is given with the description of the genus Ectothiorhodospira (see also Imhoff, 1988a).

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