Thermotoga

Thermotoga is a genus of the phylum Thermotogae. Members of Thermotoga are hyperthermophilic bacteria whose cell is wrapped in a unique sheath-like outer membrane, called a "toga".
The members of the phylum stain Gram-negative as they possess a thin peptidoglycan in between two lipid bilayers, albeit both peculiar. The peptidoglycan is unusual as the crosslink is not only meso-diaminopimelate as occurs in Proteobacteria, but D-lysine.