Rhodocista pekingensis sp nov., a cyst-forming phototrophic bacterium from a municipal wastewater treatment plant

A novel bacterial species, Rhodocista pekingensis sp. nov., was isolated from a municipal wastewater treatment plant and characterized by polyphasic taxonomy. Cells of R. pekingensis were Gram-negative, motile by a single polar flagellum, vibrioid to spiral, 0.6-0.8 mum in width and 0.8-1.5 mum in length. R-bodies were not observed. Phototrophically grown cells contained lamellar photosynthetic membranes and bacteriochlorophyll a. Cell growth was anaerobically phototrophic or aerobically chemoheterotrophic. Anaerobically grown cultures were pink-reddish. Thiamin and vitamin B-12, but not biotin, were required for growth and 0.05% yeast extract stimulated growth. Acetate, lactate, pyruvate and succinate supported growth. Cysts were formed when butyrate was used as the sole carbon source. Molecular hydrogen (H-2), but not sulfide or thiosulfate, was used as an electron donor. The major cellular quinone was Q-9. The DNA G+C content of cells was 68.8 mol%. The type strain of Rhodocista pekingensis is 3-p(T) (=AS 1.2194(T)=JCM 11669(T)).