Nutritional Types of Bacteria PDF

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Nutritional types of bacteria microbiology notes...

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NUTRITIONAL TYPES OF BACTERIA

Bacteria, like all living cells, require energy and nutrients to build proteins and structural membranes and drive biochemical processes. Bacteria require sources of carbon, nitrogen, phosphorous, iron and a large number of other minerals. Carbon, nitrogen and water are used in highest quantities. The nutritional requirements for bacteria can be grouped according to the carbon source and the energy source. Autotrophs Autotrophs are bacteria which obtain their nutrition from inorganic compounds. Carbon dioxide is typically the sole source of cellular carbon. Autotrophs will use hydrogen sulfide, ammonia or hydrogen gas to reduce carbon into necessary sugars. Nitrifying bacteria, which oxidize ammonia to create nitrites and nitrates, are an example of bacteria which use autotrophic nutrition. Heterotrophs Bacteria that require organic sources of carbon such as sugars, fats and amino acids are termed heterotrophs. Saprophytic bacteria are an example. They attain their nutrition from dead organic matter. Using enzymes, these bacteria will break own complex compounds and use the nutrients to release energy. Saprophytic bacteria are essentially decomposers and play an important role in ecosystem by releasing simpler products which plants and animals can use. Phototrophs (Photoautotroph’s) Phototrophic bacteria absorb light energy, and then utilize this in photosynthesis to create cellular energy. There are two types of phototrophs; those which do not produce oxygen as a byproduct are termed anaerobic phototrophs, while those which do produce oxygen are termed aerobic phototrophs. Cyan bacteria are an example of bacteria which execute photoautotrophic nutrition. Photoheterotrophs (Gk: photo = light, hetero = (an) other, troph = nourishment) Photohetero trophs are heterotrophic phototrophs—that is, they are organisms that use light for energy, but cannot use carbon dioxide as their sole carbon source. Consequently, they use organic compounds from the environment to satisfy their carbon requirements; these compounds include carbohydrates, fatty acids, and alcohols. Examples of photoheterotrophic organisms include purple non-sulfur bacteria, green non-sulfur bacteria, and heliobacteria. Recent research has indicated that the oriental hornet and some aphids may be able to use light to supplement their energy supply. Organotrophs: An organotroph is an organism that obtains hydrogen or electrons from organic substrates. This term is used in microbiology to classify and describe organisms based on how they obtain electrons for their respiration processes. Some organotrophs such as animals and many bacteria are also heterotrophs. Organotrophs can be either anaerobic or aerobic Methyltrophs Methyltrophs are a diverse group of microorganisms that can use reduced one-carbon compounds, such as methanol or methane, as the carbon source for their growth; and multicarbon compounds that contain no carbon bonds, such as dimethyl ether and dimethylamine. This group of microorganisms also includes those capable of assimilating reduced one-carbon compounds by way of carbon dioxide using the ribulose bisphosphate pathway.[1] These organisms should not be confused with methanogens which on the contrary produce methane as a by-product from various one-carbon compounds such as carbon dioxide. Some

other pollutants. The abundance, purity, and low price of methanol compared to commonly used sugars make methylotrophs competent organisms for production of amino acids, vitamins, recombinant proteins, single-cell proteins, co-enzymes and cytochromes. MIXOTROPH A mixotroph is an organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. Possible combinations are photo- and chemotrophy, litho- and organotrophy, auto- and heterotrophy or other combinations of these. Moxotrophs can be either eukaryotic or prokaryotic.] They can take advantage of different environmental conditions. Chemotrophs These bacteria obtain chemical energy from their surroundings and convert it into adenosine triphosphate (ATP) for cellular use. Chemotrophs attain energy from oxidation-reduction reactions of inorganic compounds such ammonia, hydrogen sulfide and iron. For instance, sulfur bacteria are a chemoautotroph which produces energy by oxidizing hydrogen sulfide into sulfur and water. Lithotrophs Lithotrophs are bacteria which use reduced inorganic compounds as the electron donor (Hdonor) in anaerobic or aerobic...