Altered patterns of cellular growth, morphology, replication and division in conditional-lethal mutants of the thermophilic archaeon Sulfolobus acidocaldarius

As a basis for studing the essential cellular processes of hyperthermophili c archaea. thermosensitive mutants of Sulfolobus acidocaldarius were isolat ed and characterized. Exponential-phase liquid cultures were shifted to the nonpermissive temperature and growth, viability. and distributions of cell mass and DNA content were measured as a function of time after the shift. The observed phenotypes demonstrate that chromosome replication, nucleoid o rganization, nucleoid partition and cell division. which normally are tight ly co-ordinated during cellular growth, can be inhibited or uncoupled by mu tation in this hyperthermophilic archaeon.