Collection, Identification, and Cultivation of Oral Protozoa

¹ Department of Biology, Illinois Wesleyan University, Bloomington, Illinois

Difficulties in establishing in precise form, or in interpreting and carrying out with success, directions for techniques in general are enumerated with emphasis on attention to clarity, chronology, comprehension of the significance of each step, and evaluation of results.

In an effort to diminish mistakes and frustrations for those who might become interested in the collection, identification, and cultivation of E. gingivalis and T. tenax, the precise steps employed in this laboratory in relation to these endeavors are listed chronologically and discussed.

Culture media that gave best results in studies on ecology, morphology, reproduction, and cytodifferentiation, by yielding near-axenic cultures of either E. gingivalis or T. tenax and near-monoxenic cultures of both protozoans grown together for from 3 to 8 months, were an egg-yolk fluid medium overlying solid egg slants. Reduction in numbers of bacteria in cultures was accomplished by (1) addition of the antibiotics penicillin and streptomycin and (2) periodic siphoning-off of the upper layers of fluid medium overlying egg slants and replacing with fresh egg-yolk fluid medium.

Examination of other studies on cultivation of Protozoa, together with observations in this laboratory, indicate that the state of axenic existence, to achieve an optimum balance and insure a high reproductive rate of Protozoa, needs to occur in an environment containing essential nutritive materials similar to those found in the normal, in vivo biome of organisms. Habitats, if altered greatly, usually result in diminished reproductive rates and lowered resistance of cultured forms.