The growth of all organisms depends on the availability of mineral nutrients, and none is more important than nitrogen, which is required in large amounts as an essential component of proteins, nucleic acids and other cellular constituents. There is an abundant supply of nitrogen in the earth's atmosphere - nearly 79% in the form of N2 gas. However, N2 is unavailable for use by most organisms because there is a triple bond between the two nitrogen atoms, making the molecule almost inert. In order for nitrogen to be used for growth it must be "fixed" (combined) in the form of ammonium (NH4) or nitrate (NO3) ions. The weathering of rocks releases these ions so slowly that it has a neglible effect on the availability of fixed nitrogen. So, nitrogen is often the limiting factor for growth and biomass production in all environments where there is suitable climate and availability of water to support life.
Microorganisms have a central role in almost all aspects of nitrogen availability and thus for life support on earth: some bacteria can convert N2 into ammonia by the process termed nitrogen fixation; these bacteria are either free-living or form symbiotic associations with plants or other organisms (e.g. termites, protozoa) other bacteria bring about transformations of ammonia to nitrate, and of nitrate to N2 or other nitrogen gases many bacteria and fungi degrade organic matte...
Currently, the United State’s Gulf of Mexico experiences an annual, seasonal “dead zone” as a result of hypoxia. Hypoxia is a low level of dissolved oxygen (<2mg/L) in an area of water. Hypoxia is typically temporary and seasonal, but the low oxygen levels can be devastating to aquatic organisms. Hypoxia occurs in many oceanic waters worldwide, but there is a growing area of concern in our Gulf of Mexico coast. Hypoxia is largely caused by nitrogen fertilizer application for agriculture, with heavy concentrations coming from the Midwestern US. Nitrogen mobilizes as nitrate, and is transported via surface water runoff. The runoff enters tile-drain supported ditches, enters streams and joins the Mississippi river, eventually reaching the gulf. Nitrate mobilization is a problem for human health, and ag. runoff is also often attributed to the contamination of surface and well-water sources in rural areas. High levels of nitrates restrict the ability of red blood cells to carry oxygen. This can harm humans, and is the major cause of infant methemoglobinemia, or “blue baby syndrome”. The safe drinking level standard is 10mg/L.
One of the main questions addressed is; why do plants choose rhizobia with nitrogen fixing strains (as nitrogen is metabolically costly) over plants with non-fixing strains that can also lead to nodulated plant (Gubry-Rangin et al, 2010). It should be noted that strains with different fixing levels have been reported in populations of rhizobia and when picking a rhizobium a plant must take into consideration its symbiotic efficacy, as rhizobia cannot be vertically transmitted.
The leguminosae family, more commonly known as the legume, pea, or bean family; contain most of the plant species that form a symbiotic relationship with nitrogen fixing bacteria. About 20,000 species of legumes form their symbiosis with rhizobia; a nodule-inducing bacteria. Legumes have emerged as a very valuable resource for many countries for various reasons. The seeds of legumes are very high in protein, and some can also be rich in oil. Some countries donate up to 60% of their arable land in order to plant various types of this plant family. This family of plants is also used to enhance soil fertility and is a valuable source of wood. In various agricultural systems, the need for chemical fertilizer is greatly reduced due to the nitrogen fixation of the symbiotic bacteria that is hosted by the legumes. In some areas, almost 50% of the nitrogen added to the soil is due to this symbiotic relationship (3). Although an exact estimate of this symbiosis is hard to determine, legume-rhizobia relationships remain important to the function and composition of many natural ecosystems throughout the world (2).
Corn helps the cows, chicken, and other animals grow faster and produce more milk, etc. as well. Instead of animals being out free in their natural environment, they are more indoors tethered to machines, eating corn. 2) All life is based on nitrogen. It forms the building blocks of organic materials and genetic information. But most of the earth's 80% nitrogen is unusable, unless it is “fixed” by combining it with hydrogen atoms. In 1909, Fritz Haber figured out how to make synthetic, usable nitrogen, which geographer Vaclav Smil calls the most important invention of the twentieth century. Without it, the human population would eventually have starved. Creating so much extra nitrogen has disrupted the natural cycle of nitrogen production. The nitrogen that isn't used by the corn evaporates into the atmosphere, which creates acid rain and speeds up global warming. The excess runoff of nitrogen-rich water makes the algae bloom in the Gulf of Mexico,
In mammals, ammonia excretion is unsuitable for disposing of nitrogenous waste on land. Mammals would have to urinate profusely to eliminate ammonia because of the toxicity, which would have to transport through the animal to be excreted in an extremely dilute solution. However...
The existence of Cyanobacteria is of vital importance to all life on planet earth. The process by which the amospehere of planet earth changed, from its early atmosphere to what it is present day is due to the process of photosynthesis, which is originated in a Cyanobacterium. Oxygenic photosynthesis is what made Cyanobacteria unique among the early organisms on planet earth whereby it used Carbon dioxide from the atmospehere and water as an electron donor to produce carbohydrates, releasing oxygen as a byproduct. In comparison, other early organisms on planet earth produced energy via
Water: Water is the most important aspect of life on Earth, whether it be for us humans or microbes. Alcamo’s Microbes and Society states that the “microbial cytoplasm is water based”. From this we can see that water absolutely must be present for the microbe to continue its life. Microbes also depend on water to dissolve essential substances that they need to survive.
...nvironmental Microbiology. New York: A John Wiley & Sons, Inc; 1992. pp. 125?156. Accessed December 2, 2013.
Ammonia (NH3) concentration in biogas does not exceed 0.1 mg/m3. The presence of ammonia in higher concentration is attributed to the increased nitrogen content of the substrate used (e.g. poultry manure).
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.
Microbial decomposition releases nutrients into the environment that are needed by other organisms. Microbes are also involved in the cycling of many other important compounds in — and between — ecosystems, including oxygen, carbon and nitrogen. Many microbes use the energy of sunlight to convert carbon dioxide to oxygen, which we need to breathe. As they do this, they create new organic material — themselves — which are then eaten by other organisms. In this way, the cycling of nutrients and energy
Humans have been performing aquaculture since Egyptian times. Aquaculture, by definition, is the process of growing aquatic organisms for consumption by human populations. Traditionally, aquaculture has been carried out in flow through systems, or pens in open water. These methods greatly increase the biogeochemical loading, as the fish excrete ammonia (~90%) and urea (~10%) (Timmons and Ebeling, 2013). The biogeochemical nitrogen cycle is driven by microorganisms, that perform nitrification, anaerobic ammonia oxidation. Nitrification leads to the production of nitrite and nitrate from the oxidation of ammonia. Ammonia and nitrite are inherently toxic to fish; however, the sensitivity to these nitrogenous compounds varies by species. It was suggested that in Cyprinus carpio, or common catfish, ammonia is regulated at the gill interface by Na+/K+-ATPase. With nitrite, fish are most sensitive in the early stages of growth; this is most often observed as poor gill structure and inflammation of muscle tissue (Kroupova et al., 2010). In a separate review, Dolomatov, et al., 2011, concluded that the most critical times for nitrite regulation are during the incubation of eggs; larvae rearing; and wintering fish.
The main biotic factors are the plants, fish, and microorganisms. The plants are the main component of an aquaponic system, and they play a significant role in forming a symbiotic ecosystem, the plants also provide water full of nutrients for the fish. Additionally, the fish play a role in forming the ecosystem, but they also assist in the growth of the of the plants by allowing for clean water to be produced from their waste. The bacteria allow for the nitrification cycle to take place, in turn, cleaning the water in the
Farmers apply nutrients such as nitrogen, phosphorus, manure, and potassium in the form of fertilizers to produce a better product for the consumers. When these sources exceed the plants needs or if these nutrients are applied before a heavy rain then the opportunity for these excess to wash into aquatic ecosystems exists.
...eochemical cycles. By increasing the amount of crops that are removed from the soil and the subsequent soil erosion, phosphorus levels in the soil have dropped. The phosphorus lost from the soils travels to aquatic ecosystems which then can cause massive algal blooms. The increased use of nitrogen based fertilizers has also altered that cycle. The fertilizers add high levels of nitrates to the soil, and in natural ecosystems, nitrates will undergo denitrification and be returned as atmospheric nitrogen. This is not the case because the nitrate levels exceed the levels of denitrification that bacteria can handle. Additionally, much of the denitrifying bacteria is found in marshes and wetlands, which are currently being destroyed at incredible rates. In some areas, the excess nitrate has made it into the ground water system and contaminated the drinking water system.