NUTRITIONAL STUDIES ON THE AMOEBO-FLAGELLATE, TETRAMITUS ROSTRATUS

¹ Department of Zoology, University of California, Berkeley 4, California

1. Tetramitus was cultivated indefinitely under axenic conditions upon a medium consisting of 0.5% Difco yeast extract, 0.5% Difco peptone and 1.0% Wilson liver concentrate (N.F.) with selected types of a autoclaved bacteria.

2. The liver concentrate could be eliminated with subsequent reduction in trophic growth, only if killed B. cereus or. B. subtilis was utilized as the bacterial fraction. Other bacteria (Neisseria catarrhalis, Escherichia coli) could not be substituted for these spore-formers in this medium.

3. It was found that the B. cereus cell contained at least two heat-stable fractions necessary for growth; neutral hydrolysis yielded a non-dialyzable fraction found in the cell-residue and a dialyzable fraction found in the bacterial cell supernatant.

4. Both factors were stable to autoclaving with 0.1 N HCl for 30 minutes at 15 pounds pressure and were retained in the acid-treated cell-residue. Alkaline hydrolysis destroyed activity of all the fractions.

5. Preliminary attempts have failed to substitute for the factors found in the neutral-hydrolyzed bacterial supernatant by employing selected vitamins, amino acids, purines and pyrimidines.