Method for the Simultaneous Establishment of Many Axenic Cultures of Paramecium*†

Abstract

A method is described for the simultaneous treatment of 42 (or more) stocks of Paramecium and their adaptation to growth in axenic culture. Samples of dense cultures of these ciliates growing with Enterobacter aerogenes are rendered bacteria-free by migration through 2 sets of tubes containing adaptation medium (Peters'' salts solution, stigmasterol, vitamins, and autoclaved E. aerogenes). The 2nd set of tubes contained adaptation medium plus antibiotics. Bacteria-free samples containing .apprx. 100 animals are transferred to test tubes containing adaptation medium without antibiotics. This medium also serves as a growth medium. It supports indefinite growth of all Paramecium stocks tested. After adaptation to this medium, the ciliates can be grown in the axenic medium developed by Soldo, Godoy and van Wagtendonk. On a single trial at least half of the stocks can be expected to produce axenic cultures within 5-10 by these procedures. The method was applied successfully to several of the species of the Paramecium aurelia complex, to all syngens of P. multimicronucleatum, several stocks of P. jenningsi and to 1 stock each of P. caudatum and P. calkinsi. A modification of the method works for Didinium nasutum.