The drug resistance of Hydrogenobacter thermophilus strain TK-6

Hydrogenobacter thermophilus</it> is an extremely thermophilic and obligately autotrophic hydrogen-oxidising bacterium with various unusual properties and believed to occupy a unique taxonomic position. Inhibitory patterns of various antibiotics on the cell growth of H. thermophilus</it> strain TK-6 clearly showed that the bacterium possessed prokaryote-type systems of DNA, RNA and protein syntheses. Effect of ionophore antibiotics supported that the bacterium was a Gram-negative bacterium, but high sensitivities against macrolide and some other antibiotics and insensitivity against polymyxin B were unusual as a Gram-negative eubacterium. Growth inhibition by cell wall synthesis inhibitors revealed the existence of peptidoglycan on the surface of H. thermophilus</it>, but ineffectiveness of cell wall lytic enzymes (lysozyme and lysostaphin) on intact cells and purified cell wall strongly suggested the uniqueness of the cell wall structure of the bacterium.