Antibacterial Lipids from Tetrahymena geleii.

1. A mixture of fatty acids which inhibited the growth of mycobacteria was obtained from lysed cultures of Tetra-hymena geleii. 2. This material could be extracted with organic solvents from the disrupted organisms and purified by reextraction into dilute alkaline solution. 3. The fatty acids in the mixture had an average chain length of 22-24 carbon atoms and represented an approximately 50/50 mixture of saturated and unsaturated acids. Myristic acid was isolated in crystalline form. 4. Partially purified preparations were active in vitro against pneumococci, streptococci, mycobacteria and staphylococci, but not against Gram-negative bacilli. Activity was greatly reduced in the presence of blood or serum. 5. No activity in vivo against infection of mice with mycobacteria or pneumococci could be demonstrated.