H2 and CO2 Evolution by Anaerobically Adapted Chlamydomonas reinhardtii F-60

Bamberger, Elchanan S.; King, Dan; Erbes, David L.; Gibbs, Martin

doi:10.1104/pp.69.6.1268

Cited by 66 publications

(31 citation statements)

References 17 publications

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“…Starch mobilization has been implicated in H 2 production from green algae (Healey, 1970;Bamberger et al, 1982;Gfeller and Gibbs, 1984;Ohta et al, 1987;Kosourov et al, 2001;Melis and Happe, 2001); however, our work directly links the disruption of a specific enzyme involved in starch metabolism to attenuated H 2 photoproduction. Two different metabolic pathways provide reductant used in the photoproduction of H 2 by algal cells anaerobically induced in the dark.…”

Section: Starch and Hydrogen Productionmentioning

confidence: 67%

“…Two different metabolic pathways provide reductant used in the photoproduction of H 2 by algal cells anaerobically induced in the dark. One of the pathways originates in PSII-catalyzed water oxidation (Bamberger et al, 1982;Greenbaum et al, 1983;Gfeller and Gibbs, 1984), and it is sensitive to the PSII inhibitor DCMU. This pathway involves the full photosynthetic electron transport chain.…”

Section: Starch and Hydrogen Productionmentioning

confidence: 99%

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Hydrogen Photoproduction Is Attenuated by Disruption of an Isoamylase Gene in Chlamydomonas reinhardtii

et al. 2004

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DNA insertional transformants of Chlamydomonas reinhardtii were screened chemochromically for attenuated H 2 production. One mutant, displaying low H 2 gas photoproduction, has a nonfunctional copy of a gene that shows high homology to the family of isoamylase genes found in several photosynthetic organisms. DNA gel blotting and gene complementation were used to link this isoamylase gene to previously characterized nontagged sta7 mutants. This mutant is therefore denoted sta7-10. In C. reinhardtii, the STA7 isoamylase gene is important for the accumulation of crystalline starch, and the sta7-10 mutant reported here contains <3% of the glucose found in insoluble starch when compared with wild-type control cells. Hydrogen photoproduction rates, induced after several hours of dark, anaerobic treatment, are attenuated in sta7 mutants. RNA gel blot analysis indicates that the mRNA transcripts for both the HydA1 and HydA2 [Fe]-hydrogenase genes are expressed in the sta7-10 mutant at greater than wild-type levels 0.5 h after anaerobic induction. However, after 1.5 h, transcript levels of both HydA1 and HydA2 begin to decline rapidly and reach nearly undetectable levels after 7 h. In wildtype cells, the hydrogenase transcripts accumulate more slowly, reach a plateau after 4 h of anaerobic treatment, and maintain the same level of expression for >7 h under anaerobic incubation. Complementation of mutant cells with genomic DNA corresponding to the STA7 gene restores both the starch accumulation and H 2 production phenotypes. The results indicate that STA7 and starch metabolism play an important role in C. reinhardtii H 2 photoproduction. Moreover, the results indicate that mere anaerobiosis is not sufficient to maintain hydrogenase gene expression without the underlying physiology, an important aspect of which is starch metabolism.

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Section: Starch and Hydrogen Productionmentioning

confidence: 67%

Section: Starch and Hydrogen Productionmentioning

confidence: 99%

Hydrogen Photoproduction Is Attenuated by Disruption of an Isoamylase Gene in Chlamydomonas reinhardtii

et al. 2004

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“…Another aspect of interest here is the anaerobic stimulatory effect of acetate on the release of CO2 and H2 in the light by C. reinhardii (3) and by other green algae ( 18,21 acetate requires ATP, Bamberger et al (3) suggested that acetate increased gas production by consuming ATP which regulated the unspecified sequence of reactions giving rise to CO2 and H2. Healey (18) modifying a mechanism put forward by Jones and Myers (20) to explain the Kok effect in blue-green algae, proposed a flow of electrons from acetate via the citric acid cycle into PSI resulting in the photoevolution of H2 from reduced Fd.…”

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confidence: 99%

Fermentative Metabolism of Chlamydomonas reinhardii

Gibbs¹,

Gfeller²,

Chen³

1986

Plant Physiol.

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The anaerobic photodissimilation of acetate by Chlamydomonas reinhardii F-60 adapted to a hydrogen metabolism was studied utilizing manometric and isotopic techniques. The rate of photoanaerobic (N2) acetate uptake was approximately 20 moles per milligram chlorophyll per hour or one-half that of the photoaerobic (air) rate. Under N2, cells produced 1.7 moles H2 and 0.8 mole CO2 per mole of acetate consumed. Gas production and acetate uptake were inhibited by monofluoroacetic acid (MFA), 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) and by H2. Acetate uptake was inhibited about 50% by 5% H2 (95% N2 (3) suggested that acetate increased gas production by consuming ATP which regulated the unspecified sequence of reactions giving rise to CO2 and H2. Healey (18) modifying a mechanism put forward by Jones and Myers (20) to explain the Kok effect in blue-green algae, proposed a flow of electrons from acetate via the citric acid cycle into PSI resulting in the photoevolution of H2 from reduced Fd. The operation of an anaerobic and light-dependent citric acid cycle which affects the stoichiometric conversion of acetate to CO2 and H2 had been documented in the photosynthetic purple bacteria ( 13).The present communication summarizes the results of a detailed investigation of the anaerobic photometabolism of acetate by C. reinhardii F-60, with reference to stoichiometry of gas (CO2 and H2) production, incorporation into cellular components, and sensitivity of the process to a variety of inhibitors. The stoichiometric relationships observed, together with the isotopic distribution following assimilation of ["4C]acetate, constitute strong evidence for the conclusion that anaerobic carbon oxidation occurs in part through the reactions of the glyoxylate and citric acid cycles. MATERIALS AND METHODSAlgal Growth Conditions. Chlamydomonas reinhardii (Dangeard) F-60, a mutant strain with an incomplete photosynthetic carbon reduction cycle but with an intact photosynthetic electron transport chain, was obtained from R. K. Togasaki, Indiana University. Cells were grown in batch cultures on an acetatesupplemented medium (14)

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“…On the other hand, Hirt et al (15) demonstrated that light can inhibit severely the rate of anaerobic glycolysis in Scenedesmus obliquus as monitored by D-lactic acid formation. Bamberger et al (2) made use of C. reinhardtii F-60, a mutant characterized by an incomplete photosynthetic carbon reduction pathway but an intact photosynthetic electron transport chain, to monitor 'true' CO2 and H2 evolution. To account for their results, they proposed an involvement between anaerobic carbohydrate metabolism and the photosynthetic electron transport chain, implying that carbohydrate degradation is entirely or partially localized in the chloroplast.…”

mentioning

confidence: 99%

Fermentative Metabolism of Chlamydomonas reinhardtii

Gfeller¹,

Gibbs²

1984

Plant Physiol.

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246

128

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The anaerobic starch breakdown into end-products in the green alg Chiamydomonas reinhardtii F-60 has been investigted in the dark and in the light. The effects of 343,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and carbonyl cyanide-p-trifluoromethoxyphenyl hydrazone (FCCP) on the fermentation in the light have also been investigted.Anaerobic starch breakdown rnte (13.1 ± 3.5 micromoles C per milligram chlorophyll per hour) is increased 2-fold by FCCP in the dark. Light (100 watts per square meter) decreases up to 4-fold the dark rate, an inhibition reversed by FCCP. Stimulation of starch breakdown by the proton ionophore FCCP points to a pH-controlled rate-limiting step in the dark, while inhibition by light, and its reversal by FCCP, indicates a control by energy charge in the light.In the dark, formate, acetate, and ethanol are formed in the ratios of 2.07:1.07:0.91, and account for roughly 100% of the C from the starch.H2 production is OA3 mole per mole glucose in the starch. Glycerol >-lactate, and CO2 have been detected in minor amounts.In the light, with DCMU and FCCP present, acetate is produced in a 1:1 ratio to formate, and H2 evolution is 2.13 moles per mole glucose. When FCCP only is present, acetate production is lower, and CO2 and H2 evolution is 1.60 and 4.73 moles per mole glucose, respectively.When DCMU alone is present, CO2 and H2 photoevolution is higher than in the dark. Without DCMU, CO2 and H2 evolution is about 100% higher than in its presence. In both conditions, acetate is not formed. In all conditions in the light, ethanol is a minor product. Formate production is least affected by light.The stoichiometry in the dark indicates that starch is degraded via the glycolytic pathway, and pyruvate is broken down into acetyl- (3,19,20,28).Classical glycolysis followed by subsequent metabolism of the pyruvate to the various end-products has been proposed to account for the anaerobic catabolism of starch or glucose in the green algae (17,19,27). Except for H2 evolution, the effect of light on fermentative carbon flow has received little attention. This is principally due to the problems involved with photosynthetic fixation of the CO2 that might be evolved fermentatively. The first to attempt to resolve this question were Klein and Betz (20) who reported that light had no effect on the rate of starch breakdown or the pattern of fermentation in Chlamydomonas moewusii. But they used extremely low levels of light (160 lux (2) made use of C. reinhardtii F-60, a mutant characterized by an incomplete photosynthetic carbon reduction pathway but an intact photosynthetic electron transport chain, to monitor 'true' CO2 and H2 evolution. To account for their results, they proposed an involvement between anaerobic carbohydrate metabolism and the photosynthetic electron transport chain, implying that carbohydrate degradation is entirely or partially localized in the chloroplast. The purpose of our study was to establish for the first time a complete fermentative balance in C. reinhardtii F-60 between...

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H₂ and CO₂ Evolution by Anaerobically Adapted Chlamydomonas reinhardtii F-60

Cited by 66 publications

References 17 publications

Hydrogen Photoproduction Is Attenuated by Disruption of an Isoamylase Gene in Chlamydomonas reinhardtii

Hydrogen Photoproduction Is Attenuated by Disruption of an Isoamylase Gene in Chlamydomonas reinhardtii

Fermentative Metabolism of Chlamydomonas reinhardii

Fermentative Metabolism of Chlamydomonas reinhardtii

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