Introduction
Bacteria capable of transferring electrons to insoluble electron acceptors such as ferric oxides and electrodes are termed as electrigens (Lovley, 2006). This very capability of transferring metabolically produced electrons to insoluble electron acceptors makes electrigens central to the idea of harvesting electricity from complex organic wastes. The devices which make use of this process to generate electricity are called microbial fuel cells (MFCs).
Mechanisms of Electron Transfer
The three main mechanisms of electron transfer in the sedimentary environment which have been proposed thus far arise from experiments conducted using MFCs. An MFC consists of an artificial anode and cathode placed in distinct compartments. The anode is reduced by the bacterial consortia and this makes electrons flow from the anode to the cathode, thus establishing the electrical circuit. Charge balance is maintained by the flow of protons across the compartments.
1. Indirect electron transfer through reduced metabolic products reacting with the anode
The first studies using MFCs involved the generation of electricity using fermentative bacterial consortia and yeast (Potter, 1911). It was thought that microbially produced reduced metabolic end-products reacted abiotically with the artificial anode driving electricity production. However, the quantification of the reduced products has not been possible and the mechanism through which this happened has never been understood well thus far. This mode of electron transfer is inefficient as not all metabolic end-products react well with the anode, with certain reduced products known to take a very long time to react.
In an anoxic sedimentary environment, hydrogen sulphide (H2S) is often a dom...
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... resulting in energy obtained to sustain microbial growth is truly a novel form of microbial respiration. The isolation of pure cultures of newer species that utilize this mechanism could help in deducing other possible mechanisms of electron transfer thorough controlled experiments. MFCs using such microbial consortia could possibly be used to power sensors to monitor water quality in natural sedimentary environments with a rich reserve of organic matter, such as in oceans and lakes.
References
Lovley, D. R. (2006). Bug juice: harvesting electricity with microorganisms. Nat Rev Microbiol, 4(7), 497-508. doi: 10.1038/nrmicro1442
Potter, M. C. (1911). Electrical Effects Accompanying the Decomposition of Organic Compounds. Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character, 84(571), 260-276. doi: 10.1098/rspb.1911.0073
Felder, M. Richard, Elementary Principles of Chemical Processes, 3rd ed.; Wiley: New Jersey, 2000; p 631.
Fermentation is the biological process which allows humans to brew beer, or any other alcoholic beverage. This process occurs in the absence of oxygen, as a means for the cell to produce adenosine triphosphate (ATP), the source of cellular energy. Though little energy can be produced in this manner, it allows the yeast to survive in t...
Linking with the idea of hydrothermal vents being a 'reactor' for RNA hydrothermal vents rely on chemical energy from geothermal vents to sustain a organisms. Swarms of bacteria thrive in this environment which acts as an interface between the high temperature vents and cold oxygenated seawater. The bacteria thrive on gases produced by the vents such as methane and use these chemicals to produce simple organic molecules to support the local ecosystem in a similar way to plants using photosynthesis. Wachtershauser has proposed that a biochemical cycle grew and assembled the first living cell.
Geobacter, as in the overall species, has the ability to transfer electrons. They also as well y get energy from organic material and biomass. They are a key part to bioredemption in destroyed habitats. When the first strain of Geobacter was discovered, the original scientist did not know how helpful it really was. Since it was first discovered in 1987, there was not a lot to explain how it work. The first strain was called Geobacter Metallireducens, and it got energy from iron oxide, in other words rust. Geobacter Sulfurreduncen on the other hand gets energy from petroleum contaminates and uranium. Geobacter Sulfurreduncen, in a sense, eats up the petroleum and turns it into carbon dioxide. Thus killing off the petroleum contaminates and uranium completely. So if the petroleum contaminates and uranium where located in a body of fresh water, that...
...id, acetic acid, formic acid, H₂ and CO₂ as fermentation products which increases ecological, industrial and basic bioenergetics interests in this particularly thermophilic bacterial specie.
All living organisms require energy. In order to obtain energy, cells within the organisms must go through the processes of cellular respiration and/or fermentation. The way in which “oxidation of glucose leads to ATP production” is emphasized in cellular respiration (Freeman et al., 2014).
I agree with him that acetyl CoA is formed in aerobic respiration from pyruvate when the oxygen is present. However, he also mentioned that acetyl CoA is produced from Krebs Cycle which do not require oxygen. I agree with Moez, the Undergraduate TA that there is a contradiction of his statement on acetyl CoA. I believe that might be a typing mistake and he chose choice C acetyl CoA as the correct answer. In Adrian’s comment on real world application of anaerobic respiration, he mentioned that anaerobic respiration affects many processes such as assimilation of carbon dioxide to acetate. In addition to that, anaerobic respiration also affects processes in bacteria such as denitrification. When there is a limited supply of oxygen, bacteria synthesize energy through denitrification. Therefore, anaerobic respiration has a significant role on bacteria production of energy when oxygen is
...hemical energy from cyanobacteria (the only bacteria that can perform photosynthesis) 2.4 billion years ago (Wernergreen). The first chloroplast came into being about one billion years ago when a single-celled protist and a cyanobacterium came together through endosymbiosis, and this first photosynthesizing eukaryotic lineage was the ancestor of land plants, green algae, and red algae. Cyanobacteria and algae endosymbionts have spread photosynthetic capabilities in such a broad range (Wernergreen). In other words, heterotrophic prokaryote cells had taken in autotrophic photosynthetic bacteria cells. The ingested cell continued to provide glucose and oxygen by photosynthesis. The host cell protected as well as provided carbon dioxide and nitrogen for the engulfed cell and overtime both cells lost the aptitude to survive without each other (Weber and Osteryoung).
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
Addition of air and mechanical mixing to enchance the growth of bacteria and ficilitate subsequent waste reduction
Overall, the advantages of lithium-ion batteries outweigh the disadvantages, thus making it a great candida...
Since development and invention takes time and money, some people question if it’s worth the effort. Some scientist are looking into another way for clean solution that doesn’t require as much funding and as much time.
Metalliferous sediments are unconsolidated deep-sea deposits that form in volcanically active areas of the ocean floor (Gurvich, 2006). These deposits are variable proportions of hydrothermal, detrital, hydrogenous, and biogenous material (Dymond et al., 1977). More simply defined, these are sediments with higher transition metal content than normal. These sediments are specifically enriched in iron, manganese and a number of other trace elements, while depleted in aluminum and titanium. This abiogenic matter is primarily produced and contributed to the ocean by means of hydrothermal vents, which emit sulfur and metal-bearing material into the ocean from Earth’s interior. Hydrothermal plumes of particle-laden fluid interact intimately with the surrounding seawater, where metal-rich marine precipitates then fall out of suspension and settle down to the ocean floor. Bonatti (1978) states that the essential feature of a metalliferous sediment is a hydrothermal Fe-Mn deposit that forms near active plate boundaries and hot spots.
Leboffe, M. J., & Pierce, B. E. (2010). Microbiology: Laboratory Theory and Application, Third Edition 3rd Edition (3rd Ed.). Morton Publishing
J. Clayden, N. Greeves, S. Warren, P. Wothers. Organic Chemistry. 8th ed. 2007, Oxford University Press, p. 1186-1191.