Chemoautotrophic growth of Thiocystis violacea, Chromatium gracile and C. vinosum in the dark at various O₂‐concentrations

Abstract

Tlie influence of various 0,-concentrations on chemoautotrophic growth was dcterniincd in thc range from microaerobic t o aerobic conditions. Chromatium vinosurn D, Thiocystis violacea 231 1 and Chromatiurn yracile 25-1 were grown chemoautotropliically using consecutively repeated batch riiltures. Rapid growth of all thrce strains occurred only under microaerobic conditions. Thc fastcst growth (1.c = 0.058) was obtained with Chromatium gracile 25-1 grown in the prcsence of 1 mg 0, . 1 -l. For optimal chemoautotrophic growth aulfur-containing cells had to bc supplied continuously with cxtracellular electron donor. Multiplication of Thiocystis violacea 231 1 and Chromatiwn gracile 25-1 was significantly inhibited after several cell generations, while Chromatiurn winosum D could be grown unlimited. I n case of the latter bacterium any given 0,-concentration determined il unique growth rate and a unique specific bclil a content. The analysis of absorption spect.ra of whole cclls revealed that different pigment complexes were regulated separately by oxygen. Growth yields were not dependent on the 0,-concentration. A growth yield of 12 g dry cell mass per mol of thiosulfate oxidized was determined for Chromatium vinosum D growing in the micro-to semiaerobic 0,-concentration range. When compared to phototrophically grown cells, the catalase content of chemotrophically grown cells was 2 times lower while the maximal specific respiration rate of the cells was 7 times higher. The ecological significance of the kinetics of chemotrophic growth under various growth conditions is discussed.

Motility of Marichromatium gracile in Response to Light, Oxygen, and Sulfide

“…In darkness M. gracile can grow chemotrophically if oxygen and reduced sulfur compounds are both present (21,22). This explains the accumulation of the bacteria at oxygen levels between 0 and 10 M in the zone where the oxygen and sulfide gradients overlap (Fig.…”

“…4). Kämpf and Pfennig (22) reported that the best chemotrophic growth conditions for M. gracile were 15 to 30 M O 2 , whereas higher concentrations caused cell lysis. Furthermore, oxygen concentrations of Ͻ10 M still allow bacteriochlorophyll synthesis, which is suppressed at higher concentrations (22).…”

“…They grow phototrophically by utilizing sulfide, intracellular sulfur, or thiosulfate as the electron donor. Under microaerobic conditions, this species can also grow chemolithotrophically with oxygen as the electron acceptor (22).…”

Nickel hydrogenases: in search of the active site

“…It has been shown that these organisms can oxidize sulphur or sulphide either anaerobically in the light or at the expense of 0 2 in the dark. They can quickly switch their energy metabolism from one mode to the other [53,110]. Purple sulphur bacteria can also grow on H 2 and CO 2 in the light.…”

Glutathione amide and its perthiol in anaerobic sulfur bacteria

“…When copper-catalyzed oxidation of cysteine, GSH, and GASH was measured as described previously (32), the rates were 19, 2.5, and 0.37 M thiol oxidized per min, respectively. Thus, GASH is very resistant to air oxidation, a property which, coupled with the presence of GASSGA reductase activity, may contribute to the ability of some Chromatium species to survive in oxygen (15) and even undergo chemoautotrophic growth on sulfide or thiosulfate under microaerophilic conditions (16,22).…”