S. Hanada et al., PORPHYROBACTER TEPIDARIUS SP-NOV, A MODERATELY THERMOPHILIC AEROBIC PHOTOSYNTHETIC BACTERIUM ISOLATED FROM A HOT-SPRING, International journal of systematic bacteriology, 47(2), 1997, pp. 408-413
A new thermophilic bacterium, strain OT3(T) (T = type strain), was iso
lated from a brackish hot spring, Strain OT3(T) is an obligate aerobe
that synthesizes bacteriochlorophyll a and has a photosynthetic appara
tus, This isolate is a thermophilic bacterium with an optimal growth t
emperature of 40 to 48 degrees C, The cells are nonmotile, ovoid to sh
ort rods. An analysis of 16S rRNA sequences revealed that the nem stra
in farms a coherent cluster with members of the alpha-4 group of the a
lpha subclass of the Proteobacteria, which contains the genera Erythro
bacter, Erythromicrobium, and Porphyrobacter. The closest relative is
Porphyrobacter neustonensis, with a 168 rRNA sequence similarity of 96
.8%. The in vivo absorption spectrum has maxima at 460, 494, 596, 800,
and 870 nm. The main carotenoids are OH-beta-carotene sulfate derivat
ives, nostoxanthin, and bacteriorubixanthinal. Growth occurs with gluc
ose, acetate, glutamate, butyrate, Casamino Acids, and yeast extract a
s sole energy sources, The pigment composition and nutritional profile
of the new isolate are similar to the pigment composition and nutriti
onal profile of P. neustonensis, Although there are marked differences
in cell morphology between the new isolate and the budding bacterium
P. neustonensis, the results of phenotypic and genetic comparisons sug
gest that the new isolate is closely related to P. neustonensis. Conse
quently, we assign the new isolate to the genus Porphyrobacter and pro
pose the name Porphyrobacter tepidaris sp, nov, for it; the type strai
n of P, tepidarius is strain OT3 (= DSM 10595).