Effect of cultivation conditions on the growth and activities of sulfur metabolism enzymes and carboxylases of Sulfobacillus thermosulfidooxidans subsp. asporogenes strain 41

The moderately thermophilic acidophilic bacterium Sulfobacillus thermosulfidooxidans subsp. asporogenes strain 41 is capable of utilizing sulfides of gold-arsenic concentrate and elemental sulfur as a source of energy. The growth in the presence of S0 under auto- or mixotrophic conditions was less stable compared with the media containing iron monoxide. The enzymes involved in oxidation of sulfur inorganic compounds--thiosulfate-oxidizing enzyme, tetrathionate hydrolase, rhodonase, adenylyl sulfate reductase, sulfite oxidase, and sulfur oxygenase--were discovered in the cells of Sulfobacillus grown in the mineral medium containing 0.02% yeast extract and either sulfur or iron monoxide and thiosulfate. Cell-free extracts of the cultures grown in the medium with sulfur under auto- or mixotrophic conditions displayed activity of the key enzyme of the Calvin cycle--ribulose bisphosphate carboxylase--and several other enzymes involved in heterotrophic fixation of carbonic acid. Activities of carboxylases depended on the composition of cultivation media.     

Effects of exogenous factors on the activity of enzymes involved in carbon metabolism in thermoacidophilic bacteria of the genus Sulfobacillus

Aerobic thermoacidophilic chemolithotrophic bacteria Sulfobacillus thermosulfidooxidans 1269T and Sulfobacillus thermosulfidooxidans subsp. asporogenes 41 were shown to be resistant to stress factors, including high concentrations of Zn2+ (0.8 M) and H+ (pH 1.2) that exceeded the optimum values. The growth and biomass gain rates decreased, but bacteria retained their functions. The activity of nearly all enzymes involved in carbon metabolism decreased. Glucose was primarily metabolized via the Entner--Doudoroff pathway. The activity tricarboxylic acid cycle enzymes decreased compared to that in cells grown under normal conditions. After saturation of the growth medium with 5 vol % CO2, sulfobacteria utilized glucose by the Embden-Meyerhof and pentose phosphate pathways under mixotrophic conditions.     

The enzyme of carbon metabolism in the thermotolerant sulfobacillus strain K1

To determine enzymatic activities in the thermotolerant strain K1 (formerly "Sulfobacillus thermosulfidooxidans subsp. thermotolerans"), it was grown in a mineral medium with (1) thiosulfate and Fe2+ or pyrite (autotrophic conditions), (2) Fe2+, thiosulfate, and yeast extract or glucose (mixotrophic conditions), and (3) yeast extract (heterotrophic conditions). Cells grown mixo-, hetero-, and autotrophically were found to contain enzymes of the tricarboxylic acid (TCA) cycle, as well as malate synthase, an enzyme of the glyoxylate cycle. Cells grown organotrophically in a medium with yeast extract exhibited the activity of the key enzymes of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways. An increased content of carbon dioxide (up to 5 vol%) in the auto- and mixotrophic media enhanced the activity of the enzymes involved in the terminal reactions of the TCA cycle and the enzymes of the pentose phosphate pathway. Carbon dioxide was fixed in the Calvin cycle. The highest activity of ribulose bisphosphate carboxylase was detected in cells grown autotrophically at the atmospheric content of CO2 in the air used for aeration of the growth medium. The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase decreased with the increasing content of CO2 in the medium.     

Telomere length in a population of long-lived people of the northwestern region of Russia

An interdisciplinary study was carried out of the telomere length and polymorphism of genes of the renin-angiotensin (ACE) and serotonin (5HTR2A and 5HTTLPR) systems in a population of old and very old inhabitants of northwestern Russia, as well as on their relationships to data from clinical and geriatric anamneses and psychological characteristics. By the method of factor analysis, a firm association was revealed between the telomere length and respondents?? age in subgroups of old and long-living respondents.     

Effects of Exogenous Factors on Enzymes of Carbon Metabolism in Thermoacidophilic Bacteria of the GenusSulfobacillus

Aerobic thermoacidophilic chemolithotrophic bacteria Sulfobacillus thermosulfidooxidans1269^Tand Sulfobacillus thermosulfidooxidanssubsp. asporogenes41 were shown to be resistant to stress factors, including high concentrations of Zn²⁺(0.8 M) and supraoptimal concentrations of H⁺(pH 1.2). The growth and biomass gain rates decreased, but bacteria retained their functions. The activity of nearly all enzymes involved in carbon metabolism decreased. Glucose was primarily metabolized via the Entner–Doudoroff pathway. The activity of tricarboxylic acid cycle enzymes decreased compared to that in cells grown under normal conditions. After saturation of the growth medium with 5 vol % CO₂, sulfobacteria utilized glucose by the Embden–Meyerhof and pentose phosphate pathways under mixotrophic conditions.     

Activity of the Enzymes of Carbon Metabolism in Sulfobacillus sibiricus under Various Conditions of Cultivation

The thermoacidophilic iron-oxidizing chemolithotroph Sulfobacillus sibiricus N1^T is characterized by steady growth and amplified cell yield when grown in vigorously aerated medium containing Fe²⁺, glucose, and yeast extract as energy sources. In this case, carbon dioxide, glucose, and yeast extract are used as carbon sources. Glucose is assimilated through the fructose-bisphosphate pathway and the pentose-phosphate pathway. The glyoxylate bypass does not function in S. sibiricus, and the tricarboxylic acid cycle is disrupted at the level of 2-oxoglutarate dehydrogenase. The presence of ribulose-bisphosphate carboxylase indicates that carbon dioxide fixation proceeds through the Calvin cycle. The activity of ribulose-bisphosphate carboxylase is highest in autotrophically grown cells. The cells also contain pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase.     

N6-dipeptide derivatives of N12-ribosyl-indolo[2,3-a]carbazole

N6-derivatives of N12-indolo[2,3-a]pirrolo[3,4-c]carbazole-5,7-dione are synthesized as potential antitumor agents. The pyrrol N6 atom of these compounds is included into the dipeptide residue of the general formula >N6-(CH₂) _n -CO-Ala/βAla-OMe (n = 2 or 3). These compounds are synthesized by the reaction in DMF at 130°C between 13-methyl-12-(2,3,4-tri-O-acetyl-β-D-ribopyranosyl)indolo[2,3-a]furano[3,4-c]carbazole-5,7-dione and dipeptides containing the free N-terminal amino group. The nitrogen atom of the peptide amino group replaces O6 in the furan ring and is embedded as the N6 imide nitrogen atom of pyrrol. The ability of the compounds obtained to inhibit the growth of the SKOV3 human ovarian carcinoma cells was studied. The only derivative containing the >N6-(CH₂)₃-CO-L-Ala-OMe radical showed the cytotoxic activity with an inhibitory concentration of IC₅₀ = 8 μM.     

Growth of Ectothiorhodospira mobilis in the dark

The purple photosynthetic bacterium Ectothiorhodospira mobilis, like E. shaposhnikovii, can grow in the dark in the presence of oxygen on organic media, in particular, containing acetate or malate. The source of sulfur may be sulfate or thiosulfate. The two bacteria grown in the light and in the dark display the activity of all the enzymes of the citric acid cycle, with the exception of alpha-ketoglutarate dehydrogenase, and possess the enzymes of the glyoxylate shunt (isocitrate lyase and malate synthase). Irrespective of the conditions of the cultural growth, active fixation of carbon dioxide by the cells of E. mobilis was found only in the light.     

Growth and Carbohydrate Metabolism of Sulfobacilli

The moderately thermophilic acidophilic bacteria Sulfobacillus thermosulfidooxidans, strain 1269, S. thermosulfidooxidanssubsp. asporogenes, strain 41, and the thermotolerant strain S. thermosulfidooxidanssubsp. thermotolerans K1 prefer mixotrophic growth conditions (the concomitant presence of ferrous iron, thiosulfate, and organic compounds in the medium). In heterotrophic and autotrophic growth conditions, these sulfobacilli can grow over only a few culture transfers. In cell-free extracts of these sulfobacilli, key enzymes of the Embden–Meyerhof–Parnas, pentose-phosphate, and Entner–Doudoroff pathways were found. The role of a particular pathway depended on the cultivation conditions. All of the enzymes assayed were most active under mixotrophic conditions in the presence of Fe²⁺and glucose, suggesting the operation of all of the three major pathways of carbohydrate metabolism under these conditions. However, the operation of the Entner–Doudoroff pathway in strain 41 was restricted under mixotrophic conditions. After the first culture transfer from mixotrophic to heterotrophic conditions, the utilization of glucose occurred only via the Embden–Meyerhof–Parnas and Entner–Doudoroff pathways. After the first culture transfer from mixotrophic to autotrophic conditions, the activity of carbohydrate metabolism enzymes decreased in all of the strains studied; in strain K1, only the glycolytic pathway remained operative. The high activity of fructose-bisphosphate aldolase, remaining in strain 41 cells under these conditions, suggests the involvement of this enzyme in the reactions of the Calvin cycle or of gluconeogenesis.