Introducation
What is Diazotroph?
Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia. A diazotroph is an organism that is able to grow without external sources of fixed nitrogen. Examples of organisms that do this are rhizobia and Frankia (in symbiosis) and Azospirillum.
Types of Diazotroph ?
Diazotrophs are scattered across bacterial taxonomic groups . Even within a species that can fix nitrogen there may be strains that do not fix nitrogen. Fixation is shut off when other sources of nitrogen are available, and, for many species, when oxygen is at high partial pressure. Bacteria have different ways of dealing with the debilitating effects of oxygen on nitrogenases,
• Free-living
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Azotobacter vinelandii is the most studied of these organisms. It uses very high respiration rates, and protective compounds, to prevent oxygen damage. Many other species also reduce the oxygen levels in this way, but with lower respiration rates and lower oxygen tolerance.
• Oxygenic photosynthetic bacteria generate oxygen as a by-product of photosynthesis, yet some are able to fix nitrogen as well. These are colonial bacteria that have specialized cells (heterocysts) that lack the oxygen generating steps of photosynthesis. Examples are Anabaena cylindrica and Nostoc commune. Other cyanobacteria lack heterocysts and can fix nitrogen only in low light and oxygen levels (e.g. Plectonema).
• Anoxygenic photosynthetic bacteria do not generate oxygen during photosynthesis, having only a single photosystem which cannot split water. Nitrogenase is expressed under nitrogen limitation. Normally, the expression is regulated via negative feedback from the produced ammonium ion but in the absence of N2, the product is not formed, and the by-product H2 continues unabated
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The bacteria also infect the roots leading to the formation of nodules. Actinorhizal nodules consist of several lobes, each lobe has a similar structure as a lateral root. Frankia is able to colonize the cortical tissue of nodules where it fixes nitrogen.[ Actinorhizal plants and Frankias also produce haemoglobins, but their role is less well established than for rhizobia. Although at first it appeared that they inhabit sets of unrelated plants (alders,Australian pines, California lilac, bog myrtle, bitterbrush, Dryas), revisions to the phylogeny of angiosperms show a close relatedness of these species and the legumes.[These footnotes suggest the ontogeny of these replicates rather than the phylogeny. In other words, an ancient gene (from before the angiosperms and gymnosperms diverged) that is unused in most species was reawakened and reused in these species.
• Cyanobacteria—there are also symbiotic cyanobacteria. Some associate with fungi as lichens, with liverworts, with a fern, and with a cycad. These do not form nodules (indeed most of the plants do not have roots). Heterocysts exclude the oxygen, as discussed above. The fern association is important agriculturally: the water fern Azolla harbouring Anabaena is an important green manure for rice
The functions of rhizoids are root-like structures that absorb water and transport materials to the plants. The position of the archegonium and antheridium relates to their reproductive function by having the archegonium located under the eggs so that when the antheridium sperm is dispersed, it can reach the egg better. Antheridium is upright so that the sperm can be dispersed on top and reach the archegonium egg to fertilize the plant. They are also located near each other so that when there is rainfall, the sperm splashes out and onto the archegonium.
In wild type culture of C-ferns, it is expected that there will be a high concentration of antheridiogen since the hermaphrodites are producing antheridiogen. The greater the population density of C-ferns, the higher the concentration of antheridiogen; hence a high percentage of male gametophytes in the wild type cultures.
Amoebae of the genus Naegleria are identified in part by their ability to create a temporary flagellate phase once exposed to nutritional scarcity. N fowleri is confirmed to be a typical eukaryotic protist by electron microscopy examination (Patterson et al., 1981).
The process of photosynthesis is present in both prokaryotic and eukaryotic cells and is the process in which cells transform energy in the form of light from the sun into chemical energy in the form of organic compounds and gaseous oxygen (See Equation Below). In photosynthesis, water is oxidized to gaseous oxygen and carbon dioxide is reduced to glucose. Furthermore, photosynthesis is an anabolic process, or in other words is a metabolism that is associated with the construction of large molecules such as glucose. The process of photosynthesis occurs in two steps: light reactions and the Calvin cycle. The light reactions of photosynthesis take place in the thylakoid membrane and use the energy from the sun to produce ATP and NADPH2. The Calvin cycle takes place in the stroma of the chloroplast and consumes ATP and NADPH2 to reduce carbon dioxide to a sugar.
Schumann, Gail L., and Cleora J. D'Arcy. Hungry Planet: Stories of Plant Diseases. St. Paul: American Phytopathological Society, 2012. Print.
Photosynthetic organisms are those who convert the sun’s energy through a process called photosynthesis. They are also referred to as autotrophs. These organisms include plants, algae, and some bacteria. These organisms take in energy from the sun and water. They then complete the steps of photosynthesis and produce oxygen and glucose. All living organisms on earth require oxygen to survive. Plants provide a continuous supply of oxygen for these organisms. Without plants, there would be less oxygen molecules present in the atmosphere, creating a potential threat to organisms that require oxygen.
...nvironmental Microbiology. New York: A John Wiley & Sons, Inc; 1992. pp. 125?156. Accessed December 2, 2013.
It is widely believed that this change was brought about by the emergence of cyanobacteria which had adapted to create energy from the sun by photosynthesis(probably due to a shortage of raw materials for energy), as a result they had began to poison the earlier anaerobic bacteria or archea with their waste product; oxygen.
“Photosynthesis (literally, “synthesis from light”) is a metabolic process by which the energy of sunlight is captured and used to convert carbon dioxide (CO2) and water (H2O) into carbohydrates (which is represented as a six-carbon sugar, C6H12O6) and oxygen gas (O2)” (BioPortal, n.d., p. 190).
Oxygen is a 'waste' product of photosynthesis. Photosynthesis takes place in the mesophyll cells inside a green plant's leaves. 6 CO2 + 6 H2O givesC6H12O6 + 6 O2 Carbon Dioxide + Water gives Glucose + Oxygen A limiting factor is one that controls a process, such as organism growth or species population size or distribution. In photosynthesis the rate is affected by three factors, temperature, carbon dioxide concentration and light. Not enough light can slow down the rate of photosynthesis, without enough light a plant cannot photosynthesise very fast, even if there is plenty of water and carbon dioxide.
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.
Oxygen (O) is one of the most important ions present in the body, making up 61% of the body’s mass. It aids in the destruction of harmful bacteria, while preserving the bacteria that is beneficial for the body. Oxygen takes on its role, and transfers the bacteria absorbed into the lungs, to the cells, allowing for cell respiration. Oxygen allows for the replacement of old cells, protection of the new ones, production of energy from the food, and decomposition of other foods (“Oxygen and Human Body,” n.d.). Oxygen is also vital to produce an activity known as metabolism, which is ‘the sum of the physical and chemical processes in an organism by which its material substance is ...
This helps consumers called heterotrophs and autotrophs use organic molecules produced by photosynthesis as a building block for growth and repair and as a source of chemical energy for cellular work. (Mader, 2013) Photosynthesis produces an enormous amount of carbohydrate that humans use to convert it into coal.
Nitrogen is essential for plants because it is an essential component of all proteins. A lack of nitrogen in a plant diet can result in slower growth, stunted growth, and even chlorosis (1). Plants affected by chlorosis produce insufficient amounts of chlorophyll, reducing its ability to make carbohydrates through photosynthesis. These plants become a yellowish or pale color and eventually die from the lack of chlorophyll. (2) All of the transformations that nitrogen goes under in and out of the soil are known as the nitrogen cycle. Plants lose nitrogen from their soil system through run-off, leaching, volatilization, and denitrification. Most of the nitrogen that plants uptake from the soil is in the forms of ammonium and nitrate. Proteins and amino acids can only be built from nitrate and ammonia and therefore must be reduced. Organic nitrogen, found in organic matter, is converted into ammonium in the process...
First type of biogeochemical cycle is nitrogen cycle. Nitrogen is abundant and chemically inert gases, constitutes of about 78% of the atmosphere. According to Stevenson and Cole (1999), accumulation in soil happens through microbial fixation of nitrogen in the presence of ammonia, nitrate and nitrite; depletion exists in the process of crop removal, leaching and volatilization. In term of that, the process of releasing compound during decomposition is called mineralization. Mineralization process is carried out by the microorganisms in which it releases carbon, and also ammonium (Sprent, 1987). As a result, many kinds of organic reduce nitrogen present, like urea, organic bases, such as purines and pyrimidines, and amino compounds. Animals have nitrogenous wastes and will eventually produce lots of nitrogen (Sprent, 1987). Several pathways are illustrated throughout the nitrogen cycle, such as nitrogen fixation, ammonification, nitrification and denitrification. Gates (1921) stated that the process of converted gaseous nitrogen into ammonia or ammonium is nitrogen fixation, while ammonium can also be produced through the decaying of nitrogenous organic substance, which is called ammonification. Afte...