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Microaerophile
A microaerophile is a microorganism that requires environments containing lower levels of dioxygen than that are present in the atmosphere (i.e. < 21% O2; typically 2–10% O2) for optimal growth. A more restrictive interpretation requires the microorganism to be obligate in this requirement. Many microaerophiles are also capnophiles, requiring an elevated concentration of (e.g. 10% CO2 in the case of '' Campylobacter'' ). The original ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capnophiles
Capnophiles are microorganisms that thrive in the presence of high concentrations of carbon dioxide (). Some capnophiles may have a metabolic requirement for carbon dioxide, while others merely compete more successfully for resources under these conditions. The term is a generally descriptive one and has less relevance as a means of establishing a taxonomic or evolutionary relationship among organisms with this characteristic. For example, the ability of capnophiles to tolerate (or utilize) the amount of oxygen that is also in their environment may vary widely and may be far more critical to their survival. Species of ''Campylobacter'' are bacterial capnophiles that are more easily identified because they are also microaerophiles, organisms that can grow in high carbon dioxide as long as a small amount of free oxygen is present, but at a dramatically reduced concentration. (In the Earth's atmosphere carbon dioxide levels are approximately five hundred times lower than that of oxy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaerobic
Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic adhesive, a bonding agent that does not cure in the presence of air *Anaerobic respiration, respiration in the absence of oxygen, using some other molecule as the final electron acceptor **Anaerobic organism, any organism whose redox metabolism does not depend on free oxygen **Anammox, anaerobic ammonium oxidation, a globally important microbial process of the nitrogen cycle **Anaerobic filter, an anaerobic digester with a tank containing a filter medium where anaerobic microbes can establish themselves **Anaerobic digestion, the use of anaerobic bacteria to break down waste, with biogas as a byproduct ***Anaerobic clarigester, an anaerobic digester that treats dilute biodegradable feedstocks and allows different retention times for solids an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactobacillus
''Lactobacillus'' is a genus of gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically diverse species; a taxonomic revision of the genus assigned lactobacilli to 25 genera (see below). ''Lactobacillus'' species constitute a significant component of the human and animal microbiota at a number of body sites, such as the digestive system and the female genital system. In women of European ancestry, ''Lactobacillus'' species are normally a major part of the vaginal microbiota. ''Lactobacillus'' forms biofilms in the vaginal and gut microbiota, allowing them to persist in harsh environmental conditions and maintain ample populations. ''Lactobacillus'' exhibits a mutualistic relationship with the human body, as it protects the host against potential invasions by pathogens, and in turn, the host provides a source of nutrients ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obligate Anaerobe
Obligate anaerobes are microorganisms killed by normal Atmosphere of Earth, atmospheric concentrations of oxygen (20.95% O2). Oxygen tolerance varies between species, with some species capable of surviving in up to 8% oxygen, while others lose viability in environments with an oxygen concentration greater than 0.5%. Oxygen sensitivity The oxygen sensitivity of obligate anaerobes has been attributed to a combination of factors including oxidative stress and enzyme production. Oxygen can also damage obligate anaerobes in ways not involving oxidative stress. Because molecular Triplet oxygen, oxygen contains two unpaired electrons in the HOMO and LUMO, highest occupied molecular orbital, it is readily reduced to superoxide () and hydrogen peroxide () within cells. A reaction between these two products results in the formation of a free hydroxyl radical (OH.). Superoxide, hydrogen peroxide, and hydroxyl radicals are a class of compounds known as reactive oxygen species (ROS), highly r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obligate Aerobe
An obligate aerobe is an organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to metabolise substances, like sugars or fats, to obtain energy. In this type of respiration, oxygen serves as the terminal electron acceptor for the electron transport chain. Aerobic respiration has the advantage of yielding more energy ( adenosine triphosphate or ATP) than fermentation or anaerobic respiration, but obligate aerobes are subject to high levels of oxidative stress."Obligate aerobe - definition from Biology-Online.org." ''Biology Online.'' Biology-Online, n.d. Web. 12 Dec 2009. Examples Among organisms, almost all animals, most fungi, and several bacteria are obligate aerobes. Examples of obligately aerobic bacteria include ''Mycobacterium tuberculosis'' (acid-fast), ''Bacillus'' (Gram-positive), and ''Nocardia asteroides'' (Gram-positive). With the exception of the yeasts, most fungi are obligate aerobes. Also, almost all algae are obliga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fermentation
Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduced by donating their electrons to other organic molecules (cofactors, coenzymes, etc.). Fermentation is important in several areas of human society. Humans have used fermentation in the production and preservation of food for 13,000 years. It has been associated with health benefits, unique flavor profiles, and making products have better texture. Humans and their livestock also benefit from fermentation from the microbes in the gut that release end products that are subsequently used by the host for energy. Perhaps the most commonly known use for fermentation is at an industrial level to produce commodity chemicals, such as ethanol and lactate. Ethanol is used in a variety of alcoholic beverages (beers, wine, and spirits) while lactate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facultative Anaerobic Organism
A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. Some examples of facultatively anaerobic bacteria are '' Staphylococcus'' spp., ''Escherichia coli'', ''Salmonella'', '' Listeria'' spp., '' Shewanella oneidensis'' and '' Yersinia pestis''. Certain eukaryotes are also facultative anaerobes, including pupfish, fungi such as ''Saccharomyces cerevisiae'' and many aquatic invertebrates such as nereid polychaetes. It has been observed that in mutants of '' Salmonella typhimurium'' that underwent mutations to be either obligate aerobes or anaerobes, there were varying levels of chromatin-remodeling proteins. The obligate aerobes were later found to have a defective DNA gyrase subunit A gene ('' gyrA''), while obligate anaerobes were defective in topoisomerase I (''topI''). This indicates that topoisomerase I and its associated relaxation of chromosomal DNA is r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaerobic Respiration
Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain. In aerobic organisms undergoing respiration, electrons are shuttled to an electron transport chain, and the final electron acceptor is oxygen. Molecular oxygen is an excellent electron acceptor. Anaerobes instead use less-oxidizing substances such as nitrate (), fumarate (), sulfate (), or elemental sulfur (S). These terminal electron acceptors have smaller reduction potentials than O2. Less energy per oxidized molecule is released. Therefore, anaerobic respiration is less efficient than aerobic. As compared with fermentation Anaerobic cellular respiration and fermentation generate ATP in very different ways, and the terms should not be treated as synonyms. Cellular respiration (both aerobic and anaerobic) uses highly reduced chemical compounds such as NADH and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobic Respiration
Cellular respiration is the process of oxidizing biological fuels using an inorganic electron acceptor, such as oxygen, to drive production of adenosine triphosphate (ATP), which stores chemical energy in a biologically accessible form. Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to transfer chemical energy from nutrients to ATP, with the flow of electrons to an electron acceptor, and then release waste products. If the electron acceptor is oxygen, the process is more specifically known as aerobic cellular respiration. If the electron acceptor is a molecule other than oxygen, this is anaerobic cellular respiration. Fermentation, which is also an anaerobic process, is not respiration, as no external electron acceptor is involved. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, producing large amounts of energy (ATP). Respiration i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetotactic Bacteria
Magnetotactic bacteria (or MTB) are a polyphyletic group of bacteria that orient themselves along the magnetic field lines of Earth's magnetic field. Discovered in 1963 by Salvatore Bellini and rediscovered in 1975 by Richard Blakemore, this alignment is believed to aid these organisms in reaching regions of optimal oxygen concentration. To perform this task, these bacteria have organelles called magnetosomes that contain magnetic crystals. The biological phenomenon of microorganisms tending to move in response to the environment's magnetic characteristics is known as magnetotaxis. However, this term is misleading in that every other application of the term taxis involves a stimulus-response mechanism. In contrast to the magnetoreception of animals, the bacteria contain fixed magnets that force the bacteria into alignment—even dead cells are dragged into alignment, just like a compass needle. Introduction The first description of magnetotactic bacteria was in 1963 by Salv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetospirillum Gryphiswaldense
''Magnetospirillum'' is a Gram-negative, microaerophilic genus of magnetotactic bacteria, first isolated from pond water by the microbiologist R. P. Blakemore in 1975. They have a spiral (helical) shape and are propelled by a polar flagellum at each end of their cells. The three main species identified are ''M. magnetotacticum'' strain MS-1, ''M. griphiswaldense'' strain MSR-1, and ''M. magneticum'' strain AMB-1. Habitat The first discovered magnetotactic bacteria came from various environments including seawater, lakes, ponds, silt and soils in 1975 – including ''Magnetospirillum''. The typical habitat of ''Magnetospirillum'' species consists of shallow fresh water and sediments, characterized by low concentrations of oxygen for growth (microaerophilic) where they live in the upper portion of the sediment ( oxic/anoxic interface) and prefer an oxygen gradient of around 1–3%. Magnetotaxis Probably the most peculiar characteristic of ''Magnetospirillum'' species is their ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
