Enrichment and Isolation Procedures

Conditions for enrichment and cultivation of Thiospirillum jenense are essentially the same as those described for Chromatium species. The large cells of T. jenense (generally 30-40 |im in length) grow only in agar shake cultures, when the final concentration of thoroughly washed agar is below 0.6-0.8% (w/v). In such agar cultures, colonies of Thiospirillum appear irregular and wisp-shaped. Individual cells can be recognized by using a low power, binocular microscope. Cultures containing not more than 1-2 mM sulfide should be incubated at low light intensity (200-500 lux). Colonies from agar shake cultures grow well in liquid medium, provided culture vessels of small volume are used first, e.g., screw-capped test tubes of 10-15-ml volume.

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