Continuous chemotrophic growth and respiration of Chromatiaceae species at low oxygen concentrations

Abstract

Abstract.Endogenous and maximum respiration rates of nine purple sulfur bacterial strains were determined. Endogenous rates were below 10 nmol 0 2 9 (mg protein.min) -1 for sulfur-free cells and 15-35nmol 02 9 (mg protein 9 min)-1 for cells containing intracellular sulfur globules. With sulfide as electron-donating substrate respiration rates were considerably higher than with thiosulfate. Maximum respiration rates of Thiocystis violacea 2711 and Thiorhodovibrio winogradskyi SSP1 (254.8 and 264.2 nmol 02 " (mg protein-min)-1, respectively) are similar to those of aerobic bacteria. Biphasic respiration curves were obtained for sulfur-free cells of Thiocvstis violacea 2711 and Chromatium vinosum 2811. In Thiocystis violacea the rapid and incomplete oxidation of thiosulfate was five times faster than the oxidation of stored sulfur. A high affinity of the respiratory system for oxygen (Kin = 0.3 0.9 gM O2, Vm,x = 260nmo1 O2" (rag protein-min) -1 with sulfide as substrate, Kin=0.6 2.4gM 02, Vmax= 14-40nmo1 O2"(mg protein -min)-1 with thiosulfate as substrate), for sulfide (K~ = 0.47 ~tM, Vm,x = 650 nmol HzS 9 (rag protein x rain) -~, and for thiosulfate (K~ = 5-6 ~tM, Vm,x = 24-72nmol S 2 0 2 -. ( m g protein-rain) -1 was obtained for different strains. Respiration of Thiocvstis violacea was inhibited by very low concentrations of NaCN (Kz = 1.7 ~tM) while CO concentrations of up to 300 gM were not inhibitory. The capacity for chemotrophic growth of six species was studied in continuous culture at oxygen concentrations of 11 to 67 gM. Thiocystis violacea 2711, Amoebobacter roseus 6611, Thiocapsa roseopersicina 6311 and Thiorhodovibrio winogradskyi SSP1 were able to grow chemotrophically with thiosulfate/acetate or sulfide/acetate. Chromatium vinosum 2811 and Amoebobacter purpureus ML1 failed to grow under these conditions. During shift from phototrophic to chemotrophic conditions intracellular sulfur and carbohydrate accumulated transiently inside the * Present address and address for correspondence: J. Overmann, Department of Microbiology, University of British Columbia, 300-6174 Umversity Boulevard, Vancouver. B.C., Canada V6T 1Z3 cells. During chemotrophic growth bacteriochlorophyll a was below the detection limit.

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

“…Thus, in the dark M. gracile oxidized sulfide, incompletely storing S 0 in its sulfur inclusions (32). Overmann and Pfennig reported molar conversion ratios of between 2.5:1 and 3.3:1 for other species of purple sulfur bacteria (31).…”

“…2). Under oxic conditions and low irradiances the cells can compensate the diminished phototrophic energy supply by respiring their sulfur inclusions with molecular oxygen (31). The flagellar motor of bacteria is driven by the proton motive force across the cell membrane (⌬p), which is built up as a result of photosynthetic and respiratory electron transport (1).…”

“…Purple sulfur bacteria are well adapted to such low concentrations. Overmann reported K m values for the oxygen and sulfide affinity of purple sulfur bacteria of 0.3 to 0.9 M O 2 and 0.47 M S tot , respectively (31). Therefore, the bacteria can avoid possible harmful effects of high oxygen or high sulfide concentrations without limiting their substrate uptake rates.…”

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).…”

Physiology of purple sulfur bacteria forming macroscopic aggregates in Great Sippewissett Salt Marsh, Massachusetts

“…Numerous Chromatiaceae species respire oxygen at high rates with sulfide, thiosulfate or intracellular sulfur present [16]. This indicates that purple sulfur bacteria in the aggregates contribute significantly to respiration.…”