Rhodospirillum centenum, sp. nov., a thermotolerant cyst-forming anoxygenic photosynthetic bacterium

Abstract

A novel non-sulfur purple photosynthetic bacterium, designated Rhodospirillum centenum, was isolated from an enrichment culture designed to favor growth of anoxygenic photosynthetic N2-fixing bacteria. R. centenum grows optimally at 40-42 degrees C and has the capacity to produce cytoplasmic 'R bodies', refractile structures not observed hitherto in photosynthetic prokaryotes. The bacterium is also unusual among photosynthetic bacteria in that it forms desiccation-resistant cysts when grown aerobically in darkness with butyrate as the sole carbon source.

Attenuated effect of oxygen on photopigment synthesis in Rhodospirillum centenum

“…The wild-type strain of R. centenum used in this study (ATCC 43720) is a thermotolerant nonsulfur purple bacterium isolated from Thermopolis Hot Springs, Wyo. (6). R. centenum FY040, that fails to synthesize a reaction center complex, and FY013, which exhibits oxygen repression of pigment biosynthesis, have been described previously (18).…”

“…R. centenum FY040, that fails to synthesize a reaction center complex, and FY013, which exhibits oxygen repression of pigment biosynthesis, have been described previously (18). R. centenum strains were routinely grown at 42°C in CENMED, a synthetic minimal medium containing pyruvate as the carbon source (6), or in CENS medium, which consists of CENMED supplemented with 0.4% Difco Soytone (13 Extraction of pigments. The total bacteriochlorophyll (Bchl) a content of cells was measured by extracting pigments from cell pellets with cold acetone-methanol (7:2) as described previously (3).…”

“…The recently discovered nonsulfur purple bacterium Rhodospirillum centenum exhibits an in vivo photopigment spectrum virtually identical with that of Rhodospirillum rubrum (6,13), to which it is closely related (on the basis of 16S rRNA sequence analysis [16]). R. centenum, however, differs from R. rubrum and from other more frequently studied photosynthetic bacteria in a number of respects.…”

Rhodocista centenaria gen. nov., sp. nov., a cyst-forming anoxygenic photosynthetic bacterium and its phylogenetic position in the Proteobacteria alpha group.

“…55°C) of the source pool at Thermopolis Hot Springs, Wyoming, U.S.A. (4). The bacterium is unusual among anoxygenic phototrophic bacteria in possessing cytoplasmic `R-body' and forming desiccation-and heat-resistant cysts when grown under aerobic conditions in the dark (4).…”

“…The bacterium is unusual among anoxygenic phototrophic bacteria in possessing cytoplasmic `R-body' and forming desiccation-and heat-resistant cysts when grown under aerobic conditions in the dark (4). Favinger et al (4) reported the bacterium to be a member of the genus Rhodospirillum on the bases of vegetative cell morphology and biochemical properties. However, the cyst-formation is a unique character and implies the possibility that the bacterium is not a member of the genus Rhodospirillum.…”