NUTRITION AND GROWTH OF SEVERAL BLUE‐GREEN ALGAE

Abstract

LITTLE ATTENTION has been given to the more general features of the physiology of the blue-green algae. Specific attention has been given to nitrogen fixation (e.g., Allison et al., 1937; Burris and Wilson, 1946; Fogg, 1947) and limited aspects of photosynthesis (e.g., Emerson and Lewis, 1942; Frenkel et al., 1950; Duysens, 1952; Brown and Webster, 1953). Nutritional requirements have been investigated, notably by Fogg (1949), Gerloff et al. (1950, 1952) and Allen (1952). However, no study has been carried to the point of developing a blue-green alga as a reliable tool organism for physiological studies. There have been two obstacles to such development. One may be attributed to the difficulties of isolation and the lack of species in pure culture which suspend readily and submit to simplicity of manipulation possible with green algae such as Chlorella and Scenedesmus. A second difficulty arises from inadequate provision of carbon dioxide inherent in most of the culture methods used. Nutritional requirements have been defined in terms of the maximum growth yield obtained in cultures in cotton-stoppered flasks. Methods have not been developed for routine study of growth rate, a characteristic far more useful and interpretable for physiological work. The' present paper presents a development of culture media and methods which has led to description of the salient growth characteristics of three blue-green algae: Anabaena variabilis, Anacystis nidulans, and Nostoc muscorum G. Fragmentary data on three other blue-green algae are included. MATERIALS AND METHODS.-Because of the uncertainties of taxonomy of the simpler algae the species used will be described in terms of their history. 1. Anabaena variabilis (Kiitzing). Filamentous, but filaments very short in turbulent culture; isolated by and obtained from R. C. Hecker as Cylindrospermum sp. (1950); revised identification by E. G. Pringsheim. 2. Anacystis nidulans. Twoto four-cell filaments, but unicellular in turbulent culture; established as a unicellular culture by one of us (WK) and purified by M. B. Allen, tentative identification by F. Drouet; original description not found. 3. Nostoc muscorum G (Kiitzing). Filamentous, but filaments short in turbulent culture; obtained from G. C. Gerloff. 4. Nostoc muscorum A (Kiitzing). Filamentous, forming clumps even in turbulent culture; isolated by and obtained from F. E. Allison. 5. Anabaena cylindrica (Lemmerman) . Fila-