Methanococcus vannielii: ultrastructure and sensitivity to detergents and antibiotics

Abstract

M. vannielii is a strictly anaerobic motile coccus that possesses a tuft of flagellae. The cells are markedly sensitive to mechanical stress and are readily lysed by detergents, but the organism grows normally in media of low ionic strength. The absence of a typical cell wall, further suggested by resistance of M. vannielii to penicillin, cycloserine and vancomycin, was confirmed by ultrastructural studies. Electron micrographs showed that the cell envelope lacks a peptidoglycan layer. On the outer surface there is a regular array of subunits similar to those of the glycoprotein envelopes of the halobacteria. The M. vannielii cell envelope, unlike those of the halobacteria, is unable to maintain a definite shape, and a high salt concentration is not required for its integrity.