The Photometabolism of Acetate by<i>Chlorella pyrenoidosa</i>

Goulding, K. H.; Merrett, M. J.

doi:10.1093/jxb/17.4.678

Cited by 53 publications

(31 citation statements)

References 10 publications

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“…Raven, unpublished) that labelling of lipids from acetate was greatly increased by illumination in C. corallina, and that this increase was much greater than could be accounted for in terms of refixation of respired ''*C02, since supplied '''^C02 gave little label in lipids. Thus refixation cannot be the w hole explanation, and some photo-system two-dependent diversion of acetate from respiration into lipid synthesis must occur (Goulding and Merrett, 1966). The products of glucose assimilation and CO2 fixation v^^ere too similar for this method to be used for glucose.…”

Section: Resultsmentioning

confidence: 99%

Energy‐dependent Processes in Chara Corallina: Absence of Light Stimulation When Only Photo‐system One Is Operative

Smith

Raven

1974

New Phytologist

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SUMMARYLight-stimulated active chloride influx in Chara corallina, like that in other giant algal cells, requires the operation of photo-system two of photosynthesis. Active phosphate influx and glucose influx also require photo-system two for light-stimulation, and are not stimulated by light under anaerobic conditions. This contrasts with the situation in Nitella and Hydrodictyon where influx of phosphate and glucose can be supported by photo-system one, i.e. by cyclic photophosphorylation alone. None of the other metabolic processes in Chara tested in this work (acetate uptake and oxidation, starch synthesis, and passive Rb+ influx), or described elsewhere in the literature, are light-stimulated when photo-system two is inoperative. Possible explanations of this apparent inability of cyclic photophosphorylation to act as a source of metabolic energy in Chara are suggested. Their significance is discussed in relation to hypotheses of the light reactions of photosynthesis and mechanisms of light-dependent solute transport.

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Section: Resultsmentioning

confidence: 99%

Energy‐dependent Processes in Chara Corallina: Absence of Light Stimulation When Only Photo‐system One Is Operative

Smith

Raven

1974

New Phytologist

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“…In C. pyrenoidosa DCMU induced a pattern of acetate assimilation in the light similar to that in the dark (Goulding & Merrett, 1966). In the presence of DCMU, in the light, less acetate carbon was incorporated into the organisms, particularly into the lipids, polysaccharide and protein, and more was released 8 s carbon dioxide, while isocitrate lyase and malate synthetase, normally repressed in the light, were induced (Goulding & Merrett, 1966). It would appear that these two algae differ in their enzyme complements and in their dependence on the light reactions of photosynthesis for acetate photo-assimilation.…”

Section: K H Goulding and M J M E R R E T Tmentioning

confidence: 86%

“…The increased yield of 14C02 in the dark was correlated with the incorporation of less acetate into the acid hydrolysate (polysaccharide+nucleic acids) fraction (Table 1). Although there was some increase in 14C incorporation into the ethanol fraction in the light (Table l), it was not as great as with Chlorella pyrenoidosa, where the bulk of the acetate carbon is incorporated into lipid in the light (Syrett et al 1964;Goulding & Merrett, 1966). …”

Section: Utilization Of Carbon Compounds For Growthmentioning

confidence: 99%

“…After 1 hr the organisms were killed either by the addition of 10 N-sulphuric acid through the side arm, or samples of suspension were placed in ice-cold centrifuge tubes which were rapidly centrifuged and the deposited organisms killed by immersion of the tubes in boiling water for 2 min. The preparation of fractions from these organisms and the determination of 14C in the fractions was as described previously (Goulding & Merrett, 1966). 14C08 evolved was absorbed by hydroxide of Hyamine (Packard Inc., Wembley) in detachable centre wells.…”

Section: Radiochemical Experimentsmentioning

confidence: 99%

“…Chlorella pyrenoidosa can assimilate and grow on acetate in the dark, growth being dependent on the induction of glyoxylate cycle enzymes (Syrett et al 1963(Syrett et al , 1964. Growth in the light is not dependent on the presence of glyoxylate cycle enzymes (Syrett et al 1963; Goulding & Merrett, 1966). Unlike C. pyrenoidosa the glyoxylate cycle is implicated in the growth of P. stellata on acetate in the light (Wiessner & Kuhl, 1962), but P. stellata will not grow on acetate in the dark.…”

Section: Introductionmentioning

confidence: 99%

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The Photo-assimilation of Acetate by Pyrobotrys (Chlamydobotrys) stellata

Goulding

Merrett

1967

Journal of General Microbiology

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SUMMARYAlcohols, amino acids, organic acids and sugars were tested as carbon sources for the growth of Pyrobotrys (Chlamydobotrys) stellata in the light and dark. Growth was only recorded with acetate in the light. A carbon balance sheet of 14C-acetate assimilation showed a greater incorporation of 14C into polysaccharide and less released as 14C02 in the light, compared with the dark. The primary products of 14C-acetate assimilation into the soluble fraction of the organisms were identified; after 10 sec. 40 % of the total 14C present in this fraction was in succinic acid, 15% in citric acid and 16 % in malic acid. The percentage of total 14C in this fraction present in succinic and malic acids decreased consistently with time, while that in citric acid initially increased before decreasing. After 10 sec. the specific activity of succinic acid was more than twice that of citric acid. 4 x M-monofluoroacetate (MFA) effectively inhibited the incorporation of 14C-acetate into tricarboxylic acid cycle intermediates and. related compounds, and markedly inhibited l4COZ evolution. ~-N1-(3-4,dichlorophenyl)-N,N-dimethyl urea (DCMU) didnot significantly inhibit 14C-metabolism. The key enzymes of the glyoxylate cycle, isocitrate lyase (E. C. 4.1 .3.1) and malate synthetase (E. C. 4.1.3.2) were found to be present in P. stellata, and did not disappear in the absence of acetate, but even so growth was not recorded on acetate in the dark.

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Improvement in the Photobiological Hydrogen Production of Aggregated Chlorella by Dimethyl Sulfoxide

et al. 2018

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Photobiological hydrogen production plays a vital role in generating clean renewable energy owing to its low energy consumption and environmental friendliness. Although materials-induced Chlorella aggregates have been developed to achieve sustained photobiological hydrogen production under normal aerobic conditions, the yield is relatively low and equals only 0.42 % of the light-to-H energy-conversion efficiency. Herein, we report that only 0.5 vol % dimethyl sulfoxide in an aqueous environment significantly enhances the H yield produced by aggregated Chlorella, reaching 0.69 % of the light-to-H energy-conversion efficiency. This improvement can be attributed to an increase in the cellular respiration rate by dimethyl sulfoxide, which results in a decrease in the oxygen content inside the aggregates and, ultimately, to the activation of more hydrogenases. More generally, this strategy consists of a functional enhancement in organism-material hybrids by using small molecules.

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The Photometabolism of Acetate byChlorella pyrenoidosa

Cited by 53 publications

References 10 publications

Energy‐dependent Processes in Chara Corallina: Absence of Light Stimulation When Only Photo‐system One Is Operative

Energy‐dependent Processes in Chara Corallina: Absence of Light Stimulation When Only Photo‐system One Is Operative

The Photo-assimilation of Acetate by Pyrobotrys (Chlamydobotrys) stellata

Improvement in the Photobiological Hydrogen Production of Aggregated Chlorella by Dimethyl Sulfoxide

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