Influence of salinity on hair formation and phosphatase activities of the blue-green alga (Cyanobacterium)Calothrix viguieriD253

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Abstract
A strain of Calothrix viguieri, isolated originally from the surface of a mangrove root, showed marked morphological and physiological responses to the salinity of the medium. When grown to P limitation in a freshwater medium, each trichome ended in a long hair and the culture showed marked cell-bound phosphomonoesterase and phosphodiesterase activities. When grown with various P sources (inorganic and organic) to P limitation in medium including 5·6 g 1-1 NaCl, hairs were absent, phosphomonoesterase activity was much lower and phosphodiesterase activity absent. With five of the seven organic P sources tested, the yield was also lower in saline medium. Reduction of NaCl concentration led to development of hairs over a 24 h period, whereas increase in NaCl led to the hairs being shed. Neither mannitol nor sorbitol led to similar effects to those brought about by NaCl. Use of an azo-dye staining technique (napthol AS-MX phosphate as P source and Fast Blue RR diazonium salt as coupling agent) showed that cell-bound phosphomonoesterase activity of cultures with hairs was localized on the hairs, with a sharp transition between the part of the trichome showing activity and that not doing so. In comparison with the phosphomonoesterase activity of other Calothrix strains tested, this strain showed a high pH optimum (above 12), an especially marked increase in activity with increasing Ca concentration, and decrease with increasing Mg; however, there was negligible response to Zn over the concentration range 0·001 to 10 mM.