Nonadaptive Growth Responses of Tetrahymena pyriformis Grown on Single Bacterial Species*

SYNOPSIS. Turbidity changes caused by ingestion of bacterial cell suspensions by Tetrahymena pyriformis W were used to measure feeding capabilities. Tetrahymena was grown on washed killed cells of Aerobacter aerogenes, Azotobacter agile, Arthrobacter sp., Bacillus megaterium, Mycobacterium lacticola, Pseudomonas fragi, Sarcinia lutea, Serratia marcescens, and Thiobacillus thioparus for 6 months with serial transfers. After this time the rate of feeding on each bacterium gave no indication of an adaptation to the food bacterium.