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 contains Adaptation Medium plus antibiotics. Bacteria-free samples containing ∼ 100 animals are then 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 & van Wagtendonk. On a single trial at least half of the stocks can be expected to produce axenic cultures within 5 to 10 days by these procedures. The method has been applied successfully to several of the species of the Paramecium aurelia complex, to all syngens of Paramecium multimicronucleatum , to several stocks of Paramecium jenningsi , and to 1 stock each of Paramecium caudatum and Paramecium calkinsi. A modification of the method also works for Didinium nasutum.