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Similarities |
Differences |
Green algae | Cyanobacteria |
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Physical |
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Both are only known microorganisms, which are able to produce photosynthetic oxygen as well as hydrogen | Eukaryotes | Prokaryotes |
Simple growth requirement that is sunlight, water and CO2 | Only green pigments | Green pigment and blue pigment (phycobilin) |
Able to grow on non-arable land | Need an external intervene for example sulphur-deprivation to establish anaerobic condition | Able to create the highly oxygen-reduced intracellular environment by itself |
Transformability, so possible for complex genetic engineering | Require exogenous fixed nitrogen source for example , | Able to fix atmospheric nitrogen |
Biomass can be further processed to make biofuels and valuable co-products | | |
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Phothosynthesis |
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Upper bound on photosynthetic efficiency ~10% (same as that for plants) | Contain two forms of chlorophyll that is chlorophyll a and b | Only chlorophyll a present. |
Having two core photosynthetic proteins that is Photosystem I and II | | |
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Hydrogen production |
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Solar to Hydrogen efficiency <0.05% | By direct recombination of protons and elections | Two hydrogen production pathways. (i) Side reaction of nitrogen fixation. (ii) Recombination of protons and electrons |
Both nitrogenase and hydrogenase are very sensitive to oxygen | Only hydrogenase enzyme is involved | Nitrogenase and hydrogenase enzymes |
| Hydrogen production is very restricted to anaerobic condition | Able to aerobically produce molecular hydrogen |
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