Isolation and Ultrastructure of the Flagella of Methanococcus thermolithotrophicus and Methanospirillum hungatei

The flagella of the archaebacteria Methanococcus thermolithotrophicus and Methanospirillum hungatei enter the cells in regions with ultrastructure resembling that of the polar organelles found in a variety of eubacteria. Flagella of both organisms consist of a filament, a hook, and a basal body with two rings similar to those of gram-positive eubacteria. The integrity of the flagella of M. thermolithotrophicus is lost in the absence of high salt concentrations, and those of both organisms are unstable at high pH. The flagellar filaments of M. hungatei are composed of two flagellins of 24 and 26 kilodaltons.