Aggregation in a Thermophilic Oscillatoria

Abstract

Oscillatoria terebriformis (Ag.) Gom., isolated from Hunter's Hot Springs, Lakeview, Oregon, shows both gliding and flexional movements of individual trichomes. Laboratory clone populations of trichomes, when dispersed by agitation, rapidly aggregate in still liquid medium. If the population density is high enough aggregation produces a single dense ball or clump. The clump may be redispersed by swirling or shaking. Fig. 1 demonstrates the rapidity of the aggregation phenomenon at an optimal temperature of 47° C. Growth in an unagitated flask takes place with essentially all of the trichomes in a single ball. At Hunter's Hot Springs and other Oregon hot springs this species forms dark brown mats up to about 2 mm in thickness from 53° C to about 47° C, which corresponds closely to the optimal growth temperature range in the laboratory. Growth medium consisted of the following (1 l. of distilled water): 0.1 g of nitrilotriacetic acid; 1.0 ml. of trace element solution (1 l. of water, 0.5 ml. of concentrated sulphuric acid, 2.28 g of manganese sulphate, 0.5 g of zinc sulphate, 0.5 g of boric acid, 0.025 g of copper sulphate, 0.025 g of sodium molybdate, 0.045 g of cobalt chloride); 0.2 mg of ferric chloride; 0.06 g of calcium sulphate; 0.1 g of magnesium sulphate; 0.008 g of sodium chloride, 0.103 g of potassium nitrate, 0.689 g of sodium nitrate; and 0.111 g of sodium phosphate. The pH was adjusted to 8.2 with sodium hydroxide, and was about 7.5 after autoclaving. Field material, when removed by suction and dispersed in a vessel, also aggregates rapidly, as in the laboratory cultures.