Chromatium purpuratum, sp. nov., a new species of the Chromatiaceae

Enrichment cultures inoculated with fragments of the sponge Ircinia spec, under autotrophic culture conditions and with thiosulfate as sole electron donor yielded the predominant development of a small cell Chromatium strain, which is described herein as the new species Chromatium purpuratum. Autotrophically grown cells are 1.2–1.7 μm wide and 3–4 μm long. The cells are motile by means of one single polar flagellum. Intracytoplasmic membranes are present as vesicles as in the other Chromatium species. Multiplication occurs by binary fission. The photopigments are bacteriochlorophyll a and carotenoids of the okenone series. The G + C content of the type strain BN 5500 is 68.9 mole%.

Chromatium purpuratum grows well photoautotrophically with sulfide or thiosulfate as electron donor. Photoheterotrophic growth is possible with various fatty acids serving as electron donor and carbon source. The new species is a marine isolate with an optimal salinity of 5% NaCl. It is compared with other known species of the genus Chromatium.