Nutrition which is also called as nourishment or aliment is a provision to the cells and organisms with the materials necessary to support life. Here it deals with the nutrition in microorganism which is called as microbial nutrition. Nutrients may be divided into three general, often overlapping categories: Those that supply energy, those that supply carbon, and those that supply any and everything else. In this lecture we will consider nutrition from the point of view of microorganisms, though many of the principles apply to macro organisms equally well.
According to Webster nutrition is something that nourishes or promotes growth and repairs the natural wastage of organic life. More specifically, nutrients are elements and specific combinations of elements (chemicals) that specific organisms require for growth and repair. Organisms can be classified according to their nutritional pattern. This, minimally, is where they obtain their energy and where they obtain their carbon. Energy source is the source of high energy electrons used to make ATP. Conversion of food to energy:
Conversion to ATP:
To be utilized as energy, an organic compound must first be converted to ATP. ii.
This is often done by first metabolically converting the nutrient molecule to a common intermediate, very often glucose (i.e., different catabolic biochemical pathways will terminate in a common product, e.g., glucose, which, in the case of glucose, is always treated as glucose regardless of the source). b.
Energy in bonds:
Glucose as well as other foodstuff intermediates contains large amounts of energy in their molecular bonds. ii.
This energy may be converted to the high energy bonds found in ATP, by a variety of processes, by different organisms. Generally these processes by which ATP is generated are referred to as fermentation and cellular respiration. Other substrates for ATP yielding catabolism
Organic, energy containing substances other than glucose include: Lipids
Inorganic, energy containing substances include various containing or consisting of: Sulfur
This is the source of the carbon atoms used in the organic compounds found in organisms. Phototroph:
An organism whose energy source is light and which can prepare its own food using light is called phototroph. Chemotroph:
An organism whose energy sources are electron-donating compounds such as glucose. This compound(s) is not necessarily an organic compound (i.e., above). Autotroph [lithotroph]
An organism whose principle carbon source is carbon dioxide. Producers:
The autotrophs are what make non-CO2 carbon compounds, using CO2 as their starting compound. Because the autotrophs are what make non-CO2 carbon compounds for everything else (i.e., other organisms which eat the autotrophs), they are known ecologically as the producers. Indeed, autotrophs are "self-feeders." Heterotroph [organotroph]
An organism which uses organic compounds as its principle source of carbon. Consumers:
Heterotrophs feed on others. That is, Heterotrophs obtain their carbon compounds by consuming other organisms. Heterotrophs are thus consumers, decomposers, scavengers, predators, herbivores, etc. Photoautotroph
An organism whose energy source is light and whose principle carbon source is carbon dioxide. Photoautotrophs include plants, algae, cyanobacteria, as well as some photosynthesizing bacteria. Photoheterotroph
Organisms whose energy source is light and which uses organic compounds as its principle source of carbon. These organisms are unable to neither convert CO2 to sugar nor produce O2. Chemoautotroph
Chemical plus CO2:
An organism whose energy sources are electron donating compounds and whose principle carbon source is carbon dioxide. These organisms tend to use inorganic electron donors (i.e., they eat rocks!).That is,...
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