BIOTYPE OF THE PURPLE NONSULFUR PHOTOSYNTHETIC BACTERIUM, RHODOSPIRILLUM-CENTENUM

Rhodospirillum centenum exhibited a number of general properties typic ally observed in nonsulfur purple bacteria, but also displayed a numbe r of unusual characteristics that include: (1) conversion of the vibri oid/spiral cells to thick-walled cysts under certain growth conditions ; (2) absence of O-2 repression of photopigment synthesis; (3) synthes is of ''R-bodies''; and (4) swarming motility on agar surfaces that al lows macroscopic observation of colony phototaxis. The unusual charact eristics indicate that Rsp.centenum will prove to be a valuable experi mental system for investigating various basic problems, especially in connection with photosensory phenomena and the regulation of photopigm ent synthesis by dioxygen and light. The present comparative study of 13 strains was undertaken to further define the Rsp. centenum biotype.