The dominant phototrophic bacterium in a water sample from a purplish red waste-water lagoon was isolated in pure culture. The individual cells of this organism were half-ring-shaped and ring-shaped before cell division; the half-rings were 0.6 to 0.7 μm wide and 2.5 to 3.0 μm long. Open or compact coils of variable length were also formed. Acetate, pyruvate, and cyclohexane carboxylate were the carbon sources best utilized by this organism; vitamin B12, p-aminobenzoic acid, and biotin were required as growth factors. The photosynthetic pigments produced by the organism are bacteriochlorophyll αp and carotenoids of the rhodopinal series. The new bacterium was facultatively aerobic and was unable to photooxidize sulfide or thiosulfate to sulfur or sulfate. It belongs to the family Rhodospirillaceae and is described herein as a member of a new genus, Rhodocyclus. The name proposed for this new species is Rhodocyclus purpureus. The type strain of R. purpureus is “Ames” 6770 (= DSM 168).

Rhodocyclus purpureus gen. nov. and sp. nov., a Ring-Shaped, Vitamin B12-Requiring Member of the Family Rhodospirillaceae

Some approaches to the study of the role of metals in the metabolism of microorganisms

http://science.sciencemag.org/content/sci/109/2840/558.full.pdf

Photoproduction of Molecular Hydrogen by Rhodospirillum rubrum

Studies on the metabolism of photosynthetic bacteria v. photoproduction of hydrogen and nitrogen fixation by rhodospirillum rubrum

Peck, H. D., Jr. (Oak Ridge National Laboratory, Oak Ridge, Tenn.). Enzymatic basis for assimilatory and dissimilatory sulfate reduction. J. Bacteriol. 82: 933–939. 1961.—Two pathways for the reduction of sulfate to sulfite in bacteria have been previously described. The substrate for sulfate reduction by extracts of yeast is 3′-phosphoadenosine-5′-phosphosulfate (PAPS) and, in contrast, the substrate for sulfate reduction in extracts of Desulfovibrio desulfuricans is adenosine-5′-phosphosulfate (APS). The enzymes catalyzing these reductions have been termed PAPS-reductase and APS-reductase, respectively. Since yeasts are “assimilatory sulfate reducers”, i.e., reduce only enough sulfate to satisfy nutritional requirements for sulfur, and D. desulfuricans is a “dissimilatory sulfate reducer”, i.e., utilizes sulfate as its terminal electron acceptor in anaerobic respiration, the pathway of sulfate reduction was determined in 25 microorganisms to ascertain whether there is a correlation between the pathway of sulfate reduction and the physiological role of sulfate in the metabolism of bacteria. Assimilatory sulfate reducers reduced sulfate in the form of PAPS, and, with one exception, APS-reductase was found only in dissimilatory sulfate reducers. APS-reductase was also found in the Thiobacilli in high specific activity and is involved in the oxidation of reduced sulfur compounds to sulfate.

S. H. Hunter

Papers

Organic Growth Essentials of the Aerobic Nonsulfur Photosynthetic Bacteria