THE ROLE OF SECRETED ACID-HYDROLASES IN THE UTILIZATION OF COMPLEX NUTRIENTS BY TETRAHYMENA

In an attempt to extend our knowledge of the biology of feeding of the ciliate Tetrahymena thermophila, this organism was grown axenically on complex organic material. The nutrient substrate was based on autoclaved wheat grains and adjusted to either pH 5.5 or 7.5. In wild type cultures the cells grew and multiplied only under acidic conditions. In cultures of a mutant cell line blocked in the secretion of acid hydrolases the cells did not grow at either pH value. Thus released acid hydrolases may play a key role in the utilization of complex nutrients in combination with uptake of small organic molecules. Mechanisms in the feeding biology of Tetrahymena thermophila and Paramecium tetraurelia are compared. © 1990 Springer-Verlag New York Inc.