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1.
H. van Gemerden 《Archives of microbiology》1968,64(2):103-110
Summary The optical density of Chromatium cultures grown anaerobically in the light with sulfide as electron donor is mainly determined by the sulfur content of the cells. Since the sulfur content varies, growth cannot be followed in this way. However, optical density measurements are very useful to characterize the moment of sulfide depletion and maximal sulfur storage. In addition to protein or cell nitrogen, increase in structural cell material in growing cultures of Chromatium can easily be followed by bacteriochlorophyll determinations, provided that the illumination intensity is higher than the saturation intensity. 相似文献
2.
H. van Gemerden 《Archives of microbiology》1968,64(2):118-124
Summary In Chromatium strain 6412 storage carbohydrate synthesized in the light, gradually disappeared in the dark. Simultaneously, poly--hydroxybutyric acid (PHB) was produced, CO2 was released and intracellular elemental sulfur was reduced to sulfide. Expressed on a molar base, the ratio between storage carbohydrate monomer (as glucose) consumed, sulfur reduced, PHB monomer produced, and sulfide released was approximately 1 : 3 : 1 : 3. This indicates that sulfur acts electron acceptor in the conversion of storage carbohydrate to PHB. Assuming that in the dark storage carbohydrate is broken down to pyruvate via the Embden-Meyerhoff pathway, whereafter PHB is synthesized from pyruvate via acetyl-CoA and acetoacetyl-CoA, the conversion of storage carbohydrate to PHB results in a net gain of 3 ATP per glycosyl unit converted. Since Thiorhodaceae are photolithotrophs, these processes would provide the organisms with maintenance energy during dark periods. They also explain motility of Chromatium in the dark. 相似文献
3.
The capacity to oxidize sulfide and the influence of the simultaneous presence of acetate in heterotrophically (acetate) and autotrophically (sulfide/CO2) grown Rhodopseudomonas capsulata was investigated.Sulfide oxidation of acetate-limited cultures was found inversely related to the specific growth rate. Upon acetate deprevation (metering pump stopped) increased rates of sulfide oxidation were observed. This points to the existence of a constitutive acceptor for the electrons from sulfide. It is suggested that a carrier functional in the light-induced cyclic electron flow operates as such. The rate of sulfide oxidation, however, is low when compared to autotrophically-grown cells. This is probably due to the low levels of Calvin cycle enzymes present in the acetate-grown cells.In cells growing on sulfide/CO2, the addition of acetate resulted in less sulfide being oxidized. Upon depletion of the acetate, the rate of sulfide oxidation again increased, however, insufficiently to maintain the accelerated growth rate. This indicates that under mixotrophic conditions the enzymes of the Calvin cycle are being synthesized to a far lesser extent.Non-Standurd Abbreviations PHB
poly--hydroxybutyric acid
- D
dilution rate
- TCA
Tri carboxylic acid cycle
- RubPcase
ribulose 1,5-bisphosphate carboxylase
- RP
reducing power 相似文献
4.
Stefan Spring Manfred Rohde Boyke Bunk Cathrin Spröer Sabine Eva Will Meina Neumann-Schaal 《Environmental microbiology》2022,24(5):2543-2575
Strain L21-Ace-BEST, isolated from a lithifying cyanobacterial mat, could be assigned to a novel species and genus within the class Deferribacteres. It is an important model organism for the study of anaerobic acetate degradation under hypersaline conditions. The metabolism of strain L21-Ace-BEST was characterized by biochemical studies, comparative genome analyses, and the evaluation of gene expression patterns. The central metabolic pathway is the citric acid cycle, which is mainly controlled by the enzyme succinyl-CoA:acetate-CoA transferase. The potential use of a reversed oxidative citric acid cycle to fix CO2 has been revealed through genome analysis. However, no autotrophic growth was detected in this strain, whereas sulfide and H2 can be used mixotrophically. Preferred electron acceptors for the anaerobic oxidation of acetate are nitrate, fumarate and dimethyl sulfoxide, while oxygen can be utilized only under microoxic conditions. Aerotolerant growth by fermentation was observed at higher oxygen concentrations. The redox cycling of sulfur/sulfide enables the generation of reducing power for the assimilation of acetate during growth and could prevent the over-reduction of cells in stationary phase. Extracellular electron transfer appears to be an essential component of the respiratory metabolism in this clade of Deferribacteres and may be involved in the reduction of nitrite to ammonium. 相似文献
5.
Simone Dannenberg Michael Kroder Waltraud Dilling Heribert Cypionka 《Archives of microbiology》1992,158(2):93-99
All of fourteen sulfate-reducing bacteria tested were able to carry out aerobic respiration with at least one of the following electron donors: H2, lactate, pyruvate, formate, acetate, butyrate, ethanol, sulfide, thiosulfate, sulfite. Generally, we did not obtain growth with O2 as electron acceptor. The bacteria were microaerophilic, since the respiration rates increased with decreasing O2 concentrations or ceased after repeated O2 additions. The amounts of O2 consumed indicated that the organic substrates were oxidized incompletely to acetate; only Desulfobacter postgatei oxidized acetate with O2 completely to CO2. Many of the strains oxidized sulfite (completely to sulfate) or sulfide (incompletely, except Desulfobulbus propionicus); thiosulfate was oxidized only by strains of Desulfovibrio desulfuricans; trithionate and tetrathionate were not oxidized by any of the strains. With Desulfovibrio desulfuricans CSN and Desulfobulbus propionicus the oxidation of inorganic sulfur compounds was characterized in detail. D. desulfuricans formed sulfate during oxidation of sulfite, thiosulfate or elemental sulfur prepared from polysulfide. D. propionicus oxidized sulfite and sulfide to sulfate, and elemental sulfur mainly to thiosulfate. A novel pathway that couples the sulfur and nitrogen cycles was detected: D. desulfuricans and (only with nitrite) D. propionicus were able to completely oxidize sulfide coupled to the reduction of nitrate or nitrite to ammonia. Cell-free extracts of both strains did not oxidize sulfide or thiosulfate, but formed ATP during oxidation of sulfite (37 nmol per 100 nmol sulfite). This, and the effects of AMP, pyrophosphate and molybdate on sulfite oxidation, suggested that sulfate is formed via the (reversed) sulfate activation pathway (involving APS reductase and ATP sulfurylase). Thiosulfate oxidation with O2 probably required a reductive first step, since it was obtained only with energized intact cells.Abbreviations
CCCP
carbonyl cyanide m-chlorophenylhydrazone
-
APS
adenosine phosphosulfate or adenylyl sulfate 相似文献
6.
《Bioscience, biotechnology, and biochemistry》2013,77(4):626-629
A sulfur-oxidizing bacterium strain NB1-3 isolated from corroded concrete was a Gram negative, non-spore-forming, and rod-shaped bacterium (0.5–1.0x 1.5–2.0μm) with a polar flagellum. Strain NB1-3 had its optimum temperature and pH for growth at 30°C and 3.0–4.0, respectively. Strain NB1-3 had enzyme activities that oxidized elemental sulfur, thiosulfate, tetrathionate, and sulfide and the activity to incorporate 14CO2 into the cells. The mean G+C content of the DNA was 52.9 mol%. These results indicate that strain NB1-3 is Thiobacillus thiooxidans. Since nickel has been known to protect concrete from corrosion, the effect of Ni on the growth of strain NB1-3 was studied. The cell growth on tiosulfate-, elemental sulfur-, or tetrathionate-medium was completely inhibited by 0.1% metal nickel or 5mM NiSO4. Both cellular activities of elemental sulfur oxidation and CO2 incorporation were strongly inhibited by 5mM NiSO4. The amounts of Ni in cells with or without nickel treatment were 1.7 and 160.0 nmol/mg protein, respectively. These results indicate that nickel binds to strain NB1-3 cells and inhibits enzymes involved in sulfur oxidation of this bacterium, and as a result, inhibits cell growth. 相似文献
7.
Gallionella ferruginea is able to utilize Fe(II) and the reduced sulfur compounds sulfide and thiosulfate as electron donor and energy source. Tetrathionate and elemental sulfur, on the other hand, are not metabolized. In sulfide-O2 microgradient cultures G. ferruginea grows at the interface between the oxidizing and the reducing zones. Optimal growth depends on low oxygen and sulfide concentrations. Establishing within the gradient protects the bacterium from too high sulfide concentrations. G. ferruginea excretes extracellular polymeric substances (EPS). While in FeS-gradient cultures 2×106 cells/ml were obtained the bacterial mass could be increased to 1–3×108 cells/ml in shaken batch cultures using thiosulfate as substrate. A further increase of bacterial mass by adding an organic carbon source was not possible confirming that G. ferruginea is an obligate autotrophic organism. When growing on sulfide or thiosulfate the otherwise characteristic twisted stalk consisting of ferric hydroxide is lacking. It is thus shown to be a metabolic end product of Fe(II) oxidation rather than metabolically active cellular material. 相似文献
8.
We have investigated hydrogen (H2) production by the cellulose-degrading anaerobic bacterium, Clostridium thermocellum. In the following experiments, batch-fermentations were carried out with cellobiose at three different substrate concentrations to observe the effects of carbon-limited or carbon-excess conditions on the carbon flow, H2-production, and synthesis of other fermentation end products, such as ethanol and organic acids. Rates of cell growth were unaffected by different substrate concentrations. H2, carbon dioxide (CO2), acetate, and ethanol were the main products of fermentation. Other significant end products detected were formate and lactate. In cultures where cell growth was severely limited due to low initial substrate concentrations, hydrogen yields of 1 mol H2/mol of glucose were obtained. In the cultures where growth ceased due to carbon depletion, lactate and formate represented a small fraction of the total end products produced, which consisted mainly of H2, CO2, acetate, and ethanol throughout growth. In cultures with high initial substrate concentrations, cellobiose consumption was incomplete and cell growth was limited by factors other than carbon availability. H2-production continued even in stationary phase and H2/CO2 ratios were consistently greater than 1 with a maximum of 1.2 at the stationary phase. A maximum specific H2 production rate of 14.6 mmol g dry cell−1 h−1 was observed. As cells entered stationary phase, extracellular pyruvate production was observed in high substrate concentration cultures and lactate became a major end product. 相似文献
9.
J. T. Pronk R. Meulenberg D. J. C. van den Berg W. Batenburg-van der Vegte P. Bos J. G. Kuenen 《Applied microbiology》1990,56(11):3395-3401
Mixotrophic growth of the facultatively autotrophic acidophile Thiobacillus acidophilus on mixtures of glucose and thiosulfate or tetrathionate was studied in substrate-limited chemostat cultures. Growth yields in mixotrophic cultures were higher than the sum of the heterotrophic and autotrophic growth yields. Pulse experiments with thiosulfate indicated that tetrathionate is an intermediate during thiosulfate oxidation by cell suspensions of T. acidophilus. From mixotrophic growth studies, the energetic value of thiosulfate and tetrathionate redox equivalents was estimated to be 50% of that of redox equivalents derived from glucose oxidation. Ribulose 1,5-bisphosphate carboxylase (RuBPCase) activities in cell extracts and rates of sulfur compound oxidation by cell suspensions increased with increasing thiosulfate/glucose ratios in the influent medium of the mixotrophic cultures. Significant RuBPCase and sulfur compound-oxidizing activities were detected in heterotrophically grown T. acidophilus. Polyhedral inclusion bodies (carboxysomes) could be observed at low frequencies in thin sections of cells grown in heterotrophic, glucose-limited chemostat cultures. Highest RuBPCase activities and carboxysome abundancy were observed in cells from autotrophic, CO2-limited chemostat cultures. The maximum growth rate at which thiosulfate was still completely oxidized was increased when glucose was utilized simultaneously. This, together with the fact that even during heterotrophic growth the organism exhibited significant activities of enzymes involved in autotrophic metabolism, indicates that T. acidophilus is well adapted to a mixotrophic lifestyle. In this respect, T. acidophilus may have a competitive advantage over autotrophic acidophiles with respect to the sulfur compound oxidation in environments in which organic compounds are present. 相似文献
10.
Ralf Steudel Gabriele Holdt Pieter T. Visscher Hans van Gemerden 《Archives of microbiology》1990,153(5):432-437
Cultures of Chromatium vinosum, devoid of sulfur globules, were supplemented with sulfide and incubated under anoxic conditions in the light. The concentrations of sulfide, polysulfides, thiosulfate, polythionates and elemental sulfur (sulfur rings) were monitored for 3 days by ion-chromatography and reversed-phase HPLC. While sulfide disappeared rapidly, thiosulfate and elemental sulfur (S6, S7 S8 rings) were formed. After sulfide depletion, the concentration of thiosulfate decreased fairly rapidly, but elemental sulfur was oxidized very slowly to sulfate. Neither polysulfides (S
x
2–
), polythionates (SnO
6
2–
, n=4–6), nor other polysulfur compounds could be detected, which is in accordance with the fact that sulfide-grown cells were able to oxidize polysulfide without lag. The nature of the intracellular sulfur globules is discussed. 相似文献
11.
Hans van Gemerden 《Microbial ecology》1974,1(1):104-119
The purpose of this study was to find a possible explanation for the coexistence of large and small purple sulfur bacteria in natural habitats. Experiments were carried out withChromatium vinosum SMG 185 andChromatium weissei SMG 171, grown in both batch and continuous cultures. The data may be summarized as follows: (a) In continuous light, with sulfide as growth rate-limiting substrate, the specific growth rate ofChr. vinosum exceeds that ofChr. weissei regardless of the sulfide concentration employed. Consequently,Chr. weissei is unable to compete successfully and is washed out in continuous cultures. (b) With intermittant light-dark illumination, the organisms showed balanced coexistence when grown in continuous cultures. The “steady-state” abundance ofChr. vinosum was found to be positively related to the length of the light period, and that ofChr. weissei to the length of the dark period. (c) Sulfide added during darkness is rapidly oxidized on subsequent illumination, resulting in the intracellular storage of reserve substances, which are later utilized for growth. The rate of sulfide oxidation/mg cell N/hr was found to be over twice as high inChr. weissei as inChr. vinosum. The observed coexistence may be explained as follows. In the light, with both strains growing, most of the sulfide will be oxidized byChr. vinosum [see (a)]. In the dark, sulfide accumulates. On illumination, the greater part of the accumulated sulfide will be oxidized byChr. weissei [see (c)]. A changed light-dark regimen should then have the effect as observed [see (b)]. These observations suggest that intermittant illumination may, at least in part explain the observed coexistence of both types of purple sulfur bacteria in nature. 相似文献
12.
Hans van Gemerden 《Archives of microbiology》1986,146(1):52-56
The utilization of sulfide by phototrophic sulfur bacteria temporarily results in the accumulation of elemental sulfur. In the green sulfur bacteria (Chlorobiaceae), the sulfur is deposited outside the cells, whereas in the purple sulfur bacteria (Chromatiaceae) sulfur is found intracellularly. Consequently, in the latter case, sulfur is unattainable for other individuals. Attempts were made to analyze the impact of the formation of extracellular elemental sulfur compared to the deposition of intracellular sulfur.According to the theory of the continuous cultivation of microorganisms, the steady-state concentration of the limiting substrate is unaffected by the reservoir concentration (S
R).It was observed in sulfide-limited continuous cultures ofChlorobium limicola f.thiosulfatophilum that higherS
R values not only resulted in higher steady-state population densities, but also in increased steady-state concentrations of elemental sulfur. Similar phenomena were observed in sulfide-limited cultures ofChromatium vinosum.It was concluded that the elemental sulfur produced byChlorobium, althouth being deposited extracellularly, is not easily available for other individuals, and apparently remains (in part) attached to the cells. The ecological significance of the data is discussed.Non-standard abbreviations RP
reducing power
- BChl
bacteriochlorophyll
- Ncell
cell material
-
specific growth rate
- {ie52-1}
maximal specific growth rate
-
D
dilution rate
-
K
s
saturation constant
-
s
concentration of limiting substrate
-
S
R
same ass but in reservoir bottle
-
Y
yield factor
- iSo
intracellular elemental sulfur
- eSo
extracellular elemental sulfur
- PHB
poly-beta-hydroxybutyric acid 相似文献
13.
Tohru Hirose Hiroyuki Suzuki Kenji Inagaki Hidehiko Tanaka Tatsuo Tano Tsuyoshi Sugio 《Bioscience, biotechnology, and biochemistry》2013,77(10):2479-2484
In Thiobacillus ferrooxidans AP19-3, elemental sulfur is oxidized by the cooperation of three enzymes, namely, hydrogen sulfide: ferric ion oxidoreductase (SFORase), sulfite: ferric ion oxidoreductase, and iron oxidase. Sulfite ions are one of the products when elemental sulfur is oxidized by SFORase. Under the conditions in which sulfite ions are accumulated in the cells, use of sulfur as an energy source by this strain was strongly inhibited. So the mechanism of inhibition by sulfite ions in T. ferrooxidans AP19-3 was studied. The activities of SFORase and iron oxidase were completely inhibited by 0.8 mm and 1.5 mm NaHSO3, respectively. 14CO2 uptake into washed intact cells was also completely inhibited by 1mm NaHSO3 when ferrous ion or elemental sulfur was used as an energy source. However, the activities of ribulose-1,5-bisphosphate carboxylase, phosphoribulokinase, and ribosephosphate isomerase measured with a cell-free extract were not inhibited by NaHSO3 at 1 mm, indicating that sulfite ions didn’t inhibit key enzymes of the Calvin cycle. Since the activity of CO2 uptake into washed intact cells was absolutely dependent on Fe2 + - or S0-oxidation, mechanism of inhibition of sulfur use by sulfite ions is proposed as follows: sulfite ions inhibit SFORase and iron oxidase, as a result T. ferrooxidans AP19-3 can not obtain a carbon source for CO2 fixation and stops cell growth on sulfur-salts medium. 相似文献
14.
From enrichment cultures with betaine (20 mM) and sulfate (20 mM) as the substrates and intertidal mud as an inoculum, a betaine-oxidizing, sulfate-reducing bacterium (strain PM4) was isolated. Strain PM4 was an oval to rod-shaped, Gram-negative, motile bacterium, which was able to oxidize lactate completely to CO2 and contained, during growth on betaine and sulfate, high activities of key enzymes of the acetyl CoA/CO dehydrogenase pathway (carbon monoxide dehydrogenase and formate dehydrogenase), but not of 2-oxo-glutarate dehydrogenase, a key enzyme of the citric acid cycle. On the basis of its morphological and physiological characteristics, strain PM4 was identified as a Desulfobacterium strain. Desulfobacterium PM4 grew on betaine with a doubling time of approximately 20 h at 30°C and produced N, N-dimethylglycine (in a 1:1 ratio) and sulfide as products. In this type of betaine metabolism one of the methyl groups of betaine is oxidized to CO2 and the reducing equivalents generated are used for the reduction of sulfate. Desulfobacterium autotrophicum (DSM 3382) grew also on betaine and sulfate with the formation of N,N-dimethylglycine, sulfide and CO2. 相似文献
15.
Günter A. Peschek 《Archives of microbiology》1978,119(3):313-322
Photosynthesis by Anacystis nidulans was studied in presence of reduced sulfur or nitrogen compounds, or of hydrogen. O2 evolution and CO2 fixation were depressed by sulfide, sulfite, cysteine, thioglycollate, hydroxylamine and hydrazine. Sulfite, cysteine and hydrazine inhibited O2 evolution much more strongly than CO2 fixation, indicating ability to supply electrons for CO2 photoreduction; DCMU suppressed these photoreductions. In contrast, some anoxygenic photosynthetic CO2 fixation insensitive to DCMU was found with sulfide, thiosulfate and hydrogen. Emerson enhancement studies confirmed that sulfite, cysteine and hydrazine acted on photosystem II, while photoreduction supported by sulfide, thiosulfate and hydrogen needed photosystem I only.Sulfite was photooxidized to sulfate, sulfide to elemental sulfur, and thiosulfate to sulfate plus elemental sulfur; the sulfur accumulated inside the cells. Results on the stoichiometries of the photoreductions were consistent with the photooxidation products determined. Inhibitor studies suggested photosynthetic CO2 fixation through the Calvin cycle.While photoreduction by all reductants used was found to be constitutive in Anacystis, the process was stimulated by anaerobic preincubation with the reductants only in the cases of hydrogen and thiosulfate; this adaptation was prevented by chloramphenicol and by O2. Anaerobic photoautotrophic growth of Anacystis was, however, not observed; the increase in dry weight with H2 and thiosulfate was not accompanied by cell multiplication or by an increase in chlorophyll content. Parallel short-term experiments with Chlorella did not reveal any constitutive photoreduction in this eukaryotic alga.Abbreviations CAP
chloramphenicol
- CCCP
carbonyl cyanide m-chlorophenylhydrazone
- DBMIB
dibromothymoquinone
- DCMU
dichlorophenyl dimethyl urea
- DSPD
disalicylidenepropane diamine-(1,3)
- EDAC
1-ethyl-3(3-dimethylaminopropyl-) carbodiimide 相似文献
16.
Epipelic diatoms are important constituents of estuarine microphytobenthic biofilms. Field‐based investigations have shown that the production of carbohydrates by such taxa is ecologically important. However, limited information exists on the dynamics of carbohydrate production by individual species of epipelic diatoms. The production of low and high molecular weight extracellular carbohydrates in axenic cultures of five species of benthic estuarine diatoms, Cylindrotheca closterium (Ehrenberg), Navicula perminuta (Grun.) in Van Heurck, Nitzschia frustulum (Kütz.) Grunow, Nitzschia sigma (Kütz.) Grunow, and Surirella ovata (Kütz.) Grunow, were investigated. All species produced colloidal (water‐soluble) carbohydrates during growth, with maximal production occurring during stationary phase. During logarithmic growth, approximately 20% of extracellular carbohydrates consisted of polymeric material (extracellular polymeric substances [EPS]), but during stationary phase, EPS content increased to 34%–50%. Pyrolysis–mass spectrophotometry analysis showed differences in the composition of EPS produced during logarithmic and stationary phase. All species synthesized glucan as a storage carbohydrate, with maximum glucan accumulation during the transition from log to stationary phase. Short‐term labeling with 14C‐bicarbonate found that between 30 and 60% of photoassimilates were released as colloidal carbohydrate, with EPS consisting of approximately 16% of this colloidal fraction. When cells were placed in darkness, EPS production increased, and between 85 and 99% of extracellular carbohydrate produced was polymeric. Glucan reserves were utilized in dark conditions, with significant negative correlations between EPS and glucan for N. perminuta and S. ovata. Under dark conditions, cells continued to produce EPS for up to 3 days, although release of low molecular weight carbohydrates rapidly ceased when cells were dark treated. Three aspects of EPS production have been identified during this investigation: (1) production during rapid growth, which differs in composition from (2) EPS directly produced as a result of photosynthetic overflow during growth limiting conditions and (3) EPS produced for up to 3 days in the dark using intracellular storage reserves (glucans). The ecological implications of these patterns of production and utilization are discussed. 相似文献
17.
The ability of nutrient‐deprived phytoplankton to recover in the short term when nutrients are resupplied has been studied for nitrogen and phosphorus, but the case for silicate (Si) is poorly understood. Si‐limited Thalassiosira weissflogii (Grunow) Fryxell et Hasle (grown in batch culture) was harvested in stationary phase (when cell numbers stopped increasing ~2 d after Si depletion) and senescence (when cell numbers declined ~4 d after Si depletion) and Si was resupplied at different concentrations (from 0 to 100 μM). Cell numbers, proportion of dead cells, variable fluorescence emissions (Fv/Fm), and activities of proteases were measured during Si depletion and for 24 h after Si resupply. As Si was depleted, the specific growth rate declined, dead cells increased from ~2% in log phase, to ~25% in stationary phase to over 35% in senescence, and activities of proteases associated with cell death increased several‐fold. Concentration‐dependent recovery of growth rate was seen after 24 h for cultures resupplied with Si in stationary phase but not in senescence. However, resupply of Si at 100 μM to stationary phase cultures alone increased protease activity to nearly the levels seen in senescence. Differences in the responses to Si resupply suggest that the ability and time to recover from Si depletion depend not only on the growth phase but also on the concentration resupplied. 相似文献
18.
SYNOPSIS. Cell size, macromolecular composition, carbohydrate utilization patterns, and O2 concentrations were measured throughout the growth stages of Naegleria gruberi in agitated cultures in a complex medium. Biphasic logarithmic growth occurred during the initial 83 hr of growth and the mean generation time was 7.0 hr and 19 hr during initial and secondary log growth stages, respectively. The maximum yield was 5 × 10* amebaeJml. The pH rose rapidly (1 pH unit) during the secondary log growth phase (52-83 hr) and continued into the stationary growth phase (83-120 hr). Dry weight, total protein, carbohydrate, and RNA per ameba increased just before the secondary log growth phase. RNA increased 31% to 35% per ameba at the end of each phase of log growth. DNA increased ~ 2-fold throughout the different growth phases. Average cell size increased 90% during biphasic log growth then decreased during stationary phase. O2 tension decreased from 100% to 18% of saturation during the biphasic growth phase, then increased during stationary growth to near 100% saturation. Glucose and total carbohydrate assays showed little utilization of those substrates throughout the growth stages. Naegleria gruberi presumably has a predominantly aerobic metabolism, also its metabolism may change during the different growth phases. 相似文献
19.
W. Hüsemann 《Protoplasma》1981,109(3-4):415-431
Summary This communication reports the photoautotrophic growth of hormone and vitamin independent cell suspension cultures ofChenopodium rubrum. The transfer of cells from stationary growth into fresh culture medium results in a high protein formation, followed by an exponential phase of cell division, whereas the onset of rapid chlorophyll formation is delayed for 4 days. At the stage of most rapid cell division there is no net synthesis of starch and sugar. When the cells enter stationary growth, there is a progressive accumulation of chlorophyll, sugar, and starch.Photoautotrophic cell cultures assimilate about 80–90 mol CO2/mg chlorophyll X hour. Dark CO2 fixation is about 3.7% to 2.2% of the light values during exponential and stationary growth, respectively. As shown by short-term14CO2 fixation, CO2 is predominantly assimilated through ribulosebisphosphate carboxylase via the Calvin pathway. There is a significant increase in the14C label of C4 carboxylic acids in exponentially dividing cells as compared to cells from stationary growth. Thein vitro activity of phosphoenolpyruvate carboxylase and ribulosebisphosphate carboxylase is almost equal during exponential cell division. A decrease in cell division activity is accompanied by a significant change in the specific activities of both carboxylation enzymes. In non dividing cells from stationary growth the activity of ribulosebisphosphate carboxylase is greately enhanced and that of phosphoenolpyruvate carboxylase is reduced, documenting the development of carboxylation capacities typical for C3-plants.The experimental results provide evidence that phosphoenolpyruvate carboxylase activity might be regulated by ammonia and could be involved in anaplerotic CO2 fixation which supplies carbon skeletons of the citric acid cycle.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- EDTA
ethylene-diamine-tetraacetic acid
- FDP
fructose bisphosphate
- F-6-P
fructose-6-phosphate
- G-6-P
glucose-6-phosphate
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- PGA
3-phosphoglyceric acid
- PEP
phosphoenolpyruvate
- RuDP
ribulosebisphosphate 相似文献
20.
Two bacterial strains were dominant in anaerobic enrichment cultures with betaine (N,N,N-trimethylglycine) as a substrate and intertidal mud as an inoculum. One was a coccoid bacterium which was a trimethylamine (TMA)-fermenting methanogen similar to Methanococcoides methylutens. The other strain, a rod-shaped, gram-negative, motile bacterium, fermented betaine. On the basis of its ability to oxidize acetate and ethanol to CO2 with sulfur as an electron acceptor, its inability to reduce sulfate and sulfite, its morphology, the presence of c-type cytochromes, and other characteristics, the isolated strain PM1 was identified as Desulfuromonas acetoxidans. Although only malate and fumarate were known as substrates for fermentative growth of this species, the type strain (DSM 684) also fermented betaine. Strain PM1 grew with a doubling time of 9.5 h at 30°C on betaine and produced approximately 1 mol of TMA per mol of betaine, 0.75 mol of acetate, and presumably CO2 as fermentation products but only in the presence of selenite (100 nM). In this fermentation, betaine is probably reductively cleaved to TMA and acetate, and part of the acetate is then oxidized to CO2 to provide the reducing equivalents for the initial cleavage reaction. In the presence of sulfur, betaine was converted to TMA and presumably CO2 with the formation of sulfide; then, only traces of acetate were produced. 相似文献