Jk. Kristjansson et al., THERMUS-SCOTODUCTUS, SP-NOV, A PIGMENT-PRODUCING THERMOPHILIC BACTERIUM FROM HOT TAP WATER IN ICELAND AND INCLUDING THERMUS SP X-1, Systematic and applied microbiology, 17(1), 1994, pp. 44-50
Thermophilic, aerobic heterotrophic bacteria, producing a water solubl
e dark brown melanin-like pigment, were isolated from a hot water pipe
line in a small town in southern Iceland. The bacteria stained Gram-ne
gative, are short rods, 1.5 mum long and 0.5 mum in diameter. The cell
s vare usually single or in pairs. A very dense peptidoglycan layer wa
s seen as well as cytoplasmic membrane and an outer membrane. The bact
eria are nonmotile and do not form spores. They could grow at 42-73-de
grees-C with optimum growth temperature of 65-degrees-C and optimum pH
at 7.5. The bacteria were oxidase and catalase positive, sensitive to
the antibiotics penicillin, erythromycin, tetracyclin, chloramphenico
l and streptomycin but resistant to polymyxin B and rifampicin. The GC
was about 64.5%. The isolates were compared to other known aerobic, h
eterotrophic bacteria and turned out to resemble to colourless Thermus
strain X-1, which was also found to produce the brown pigment. The DN
A:DNA similarity between the new isolates and Thermus X-1 was about 83
%, whereas the similarity with Thermus aquaticus was about 46%. The ne
w isolates together with strain X-1 are therefore considered to repres
ent a new species, Thermus scotoductus.