Abstract
As part of a study to establish the role of hairs in blue-green algae, a strain of Calothrix parietina was isolated from Sand Sike, Upper Teesdale. The stream typically has low levels of soluble reactive phosphorus but occasional high pulses of organic phosphorus do occur. During growth in batch culture long hairs developed under conditions of phosphorus deficiency when the level of cellular phosphorus had dropped to about 0 multiplied by 1% dry weight. Alkaline phosphatase activity was high under phosphorus deficiency and histochemical techniques (including lead-salt and azo-dye methods) showed the enzyme was present in the cell walls, including the hairs, and in the sheath material. Assays with various organic substrates demonstrated the alga has phosphomonoesterase (including phytase) and phosphodiesterase enzymes. These enzymes are likely to be important for the growth of the alga in its natural conditions where the dominant phosphorus source is in the soluble organic fraction.