Particulate material as a prerequisite for rapid cell multiplication in Tetrahymena cultures

Abstract

1. 1. Tetrahymena pyriformis GL, cultivated axenically in 2 % proteose peptone in slanted test tubes at 28°C, had a population doubling time of more than 40 h when the medium was sterilized by asbestos pad or membrane filtration. Under these conditions the cultures could not be propagated successfully. 2. 2. The doubling time was reduced to 5 h or less when the medium was sterilized in the autoclave instead of by filtration. 3. 3. Various additives improved the growth potential of the sterile-filtered proteose peptone. These included both insoluble materials such as talcum, quartz, clay and calcium carbonate, and water-soluble compounds which through hydrolytic decomposition readily produce insoluble particles in aqueous solution, as, for example, ferrous ammonium sulphate, ferrous sulphate and potassium aluminium sulphate. Other water-soluble compounds such as amino acids, purines, pyrimidines, vitamins and glucose, added either singly or in combination to the sterile-filtered broth, did not significantly improve the rate of cell multiplication. 4. 4. The average number of food vacuoles present in the cells of a culture was observed to be correlated with the growth potential of the medium. 5. 5. On the basis of these observations it is suggested that formation of food vacuoles in Tetrahymena induced by the presence of particulate material is a condition for rapid multiplication of the cells.