![]() In our experiments, anaerobic production of dissolved inorganic carbon was consistently accompanied by large dissolved H 2 production rates, suggesting the presence of fermentation. Here we present analyses of flow-through reactor experiments showing that dissolved inorganic carbon is produced predominantly as a result of anaerobic eukaryotic metabolic activity. Organic matter in permeable sediments is dominated by microalgae, which as eukaryotes have different anaerobic metabolic pathways to prokaryotes such as bacteria and archaea. ![]() Permeable sediments are common across continental shelves and are critical contributors to marine biogeochemical cycling. Hasler-Sheetal, Harald Kamalanathan, Manoj Beardall, John Greening, Chris Cook, Perran L.M. We conclude that microalgal dark fermentation could be an important energy-conserving pathway in permeable sediments.īourke, Michael F Marriott, Philip J. H 2 production was observed in dark anoxic cultures of diatoms (Fragilariopsis sp.) and a chlorophyte (Pyramimonas) isolated from the study site, substantiating the hypothesis that microalgae undertake fermentation. Cell counts revealed a predominance of microalgae in the sediments. ![]() Metabolomic analysis showed large increases in lipid production at the onset of anoxia, consistent with documented pathways of anoxic dark fermentation in microalgae. Metronidazole inhibits the ferredoxin/hydrogenase pathway of fermentative eukaryotic H 2 production, suggesting that pathway as the source of H 2 and dissolved inorganic carbon production. The production of both dissolved inorganic carbon and H 2 persisted following administration of broad spectrum bactericidal antibiotics, but ceased following treatment with metronidazole. Organic matter in permeable sediments is dominated by microalgae, which as eukaryotes have different anaerobic metabolic pathways to bacteria and archaea. Hasler-Sheetal, Harald Kamalanathan, Manoj Beardall, John Greening, Chris Cook, Perran L. Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentationīourke, Michael F. Control of p H at 7.0 was found optimum for bacteria cooperation in the co-culture what resulted in obtaining 2.533 L H 2/L(medium) and H 2 yield of 6.22 mol H 2/mol glucose. Fixed p H value has proven to be an important control strategy also for the hybrid process and resulted in obtaining balanced co-culture of dark and photofermentative bacteria. Results have shown that p H control at p H 7.5 increased photofermentative hydrogen production from 0.966 to 2.502 L H 2/L(medium) when compared to uncontrolled process. However, it only slightly affected cumulative H 2 volume. ![]() Increasing p H during dark fermentation resulted in lower hydrogen production rate (HPR) and longer lag time for both controlled and uncontrolled conditions. Single stage dark fermentation, photofermentation and hybrid co-culture systems were studied at different values of controlled and uncontrolled p H. The role of p H control on biohydrogen production by co-culture of dark-fermentative Clostridium acetobutylicum and photofermentative Rhodobacter sphaeroides was studied. The role of p H control on biohydrogen production by single stage hybrid dark- and photo- fermentation. ![]()
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