A., dying in the presence of free oxygen in the environment ... Big Medical Dictionary
See Anaerobic Organisms. Geological dictionary: in 2 volumes. M.: Nedra. Edited by K. N. Paffengolts et al. 1978 ... Geological Encyclopedia
Modern Encyclopedia
- (anaerobic organisms) are able to live in the absence of atmospheric oxygen; some types of bacteria, yeast, protozoa, worms. Energy for life is obtained by oxidizing organic, less often inorganic substances without the participation of free ... ... Big Encyclopedic Dictionary
Anaerobes- (from the Greek an negative particle, aer air and bios life), organisms that can live and develop in the absence of free oxygen; some types of bacteria, yeast, protozoa, worms. Obligate, or strict, anaerobes develop ... ... Illustrated Encyclopedic Dictionary
Organisms (mainly prokaryotes) that can live in the absence of free oxygen in the environment. Obligate A. receive energy as a result of fermentation (butyric acid bacteria, etc.), anaerobic respiration (methanogens, sulfate-reducing bacteria ... Dictionary of microbiology
Ow, pl. (unit anaerobe, a; m.). Biol. Organisms capable of living and developing in the absence of free oxygen (cf. aerobes). ◁ Anaerobic, oh, oh. Ah, bacteria. Ah, the infection. * * * anaerobes (anaerobic organisms), able to live in the absence of ... ... encyclopedic Dictionary
I Anaerobes (Greek negative prefix an + aēr air + b life) are microorganisms that develop in the absence of free oxygen in their environment. They are found in almost all samples of pathological material with ... ... Medical Encyclopedia
Anaerobic organisms, anaerobionts, anoxybionts (from the Greek an negative particle and Aerobes), organisms that can live and develop in the absence of free oxygen and receive energy for life by splitting ... ... Great Soviet Encyclopedia
ANAEROBES- (from the Greek an negative particle, aer air and bios life), organisms that can live and reproduce in the absence of atm. oxygen. They receive energy for life by splitting Ch. arr. organic substances without the participation of free oxygen. Veterinary Encyclopedic Dictionary
a) bacteroids
b) clostridia
c) bifidobacteria
162. Enzymes constantly synthesized in microbial cells:
d) constitutive
163. Enzymes, the synthesis of which depends on the presence of a substrate:
a) inducible
164. According to the type of nutrition, clinically significant types of microorganisms:
d) chemoheterotrophs
165. According to the type of respiration, clinically significant microorganisms are mainly:
d) facultative anaerobes
166. Phases of development of a bacterial population (except for me):
e) binary fission
167. Selective intake of substances into a bacterial cell mainly ensures:
168. Bacteria by type of respiration (except for me):
a) microaerophiles
c) obligate aerobes
d) facultative anaerobes
169. Methods of reproduction of prokaryotes (except for me):
170. Method of reproduction of bacteria:
b) binary division
171. Bacteria are most biochemically active in:
b) logarithmic phase
172. Bacteria are most sensitive to antibiotics in:
b) logarithmic phase
173. Mechanisms for the entry of substances into a bacterial cell (except for me):
e) phagocytosis
174. Entry of substances into a bacterial cell without energy expenditure occurs when:
b) simple diffusion
175. Microorganisms that need a lower concentration of 0 2 than its content in the air:
d) microerophiles
176. The ability of anaerobic microorganisms to exist in the presence of free 0 2
b) aerotolerance
177. Type of metabolism of obligate anaerobes:
b) fermentation
178. Type of metabolism of facultative anaerobic microorganisms:
c) oxidative, fermentative
179. Methods for creating anaerobiosis (except for me):
e) genotypic
180. To create anaerobiosis in a physical way use:
b) anaerostat
181. Physical Methods Anaerobiosis creations are based on:
a) mechanical removal of oxygen
182. To create anaerobiosis in a chemical way, use:
b) Bittner method
183. Chemical Methods Anaerobiosis creations are based on:
b) the use of chemical sorbents
184. To create anaerobiosis biologically use:
e) Fortner method
185. To create anaerobiosis in a combined way, use (except for):
e) Bittner method
186. Obligate anaerobes:
c) clostridia
187. Fortner biological method for oxygen removal uses:
d) sarcina
188. The purpose of the P stage of the tank method:
c) accumulation of pure culture
189. Purpose of the third stage of the tank method:
d) pure culture identification
190. At stage III of the tank method:
d) determine species properties and antibiograms
191. The purpose of culture microscopy at stage III of the bacterial method is to determine:
a) morphological and tinctorial uniformity
192. Mobility of bacteria is determined by:
b) when sowing by injection into a column of semi-liquid agar
193. The principle of determining the biochemical activity of bacteria:
194. The principle of determining the biochemical activity of bacteria:
b) determination of intermediate and end products of metabolism
195. To determine biochemical properties microorganisms are used (in addition to m e):
d) tissue cell culture
196. Saccharolytic activity of bacteria is evidenced by:
c) the formation of acidic and gaseous metabolic products
197. Saccharolytic properties of bacteria are determined on the medium:
198. Proteolytic properties of bacteria are determined on media with (except for me):
c) carbohydrates
199. The criterion for taking into account when determining the proteolytic properties of bacteria on the BCH:
d) the formation of hydrogen sulfide, indole
200. The purity of the culture at stage III of the tank method is evidenced by:
c) homogeneity of growth and uniformity of microorganisms in a smear
201. A pure culture is a population of bacteria of one:
202. Population of bacteria of one species:
b) pure culture
203. Determination of antibiograms of cultures is caused by:
d) acquisition of drug resistance
204. Determination of antibiograms of cultures is caused by:
b) acquisition of drug resistance
205. When determining the antibiogram by the disk method (except for):
b) sow the culture using the "stroke with a platform" method
206. Determination of antibiogram is carried out (except for):
d) for the identification of microorganisms
207. Main taxon of prokaryotes:
208. A species is a population of microorganisms similar in (except for):
e) sexual reproduction
209. Within a species, microorganisms may differ in (except for):
b) the ability to sporulate
210. Within a species, microorganisms may differ in (except for):
a) Gram stain
211. Taxa of prokaryotes (except for me):
212. A species is a population of microorganisms similar in (except for):
e) sensitivity to antibiotics
213. For the identification of microorganisms according to Bergey determine (except for me):
b) sensitivity to antibiotics
214. The basic principle of identification of bacteria according to Bergey:
c) structure cell wall and relation to Gram stain
215. Enzymes of microorganisms provide (except for):
e) morphology
216. Enzymes of microorganisms are determined by decomposition:
c) appropriate substrate
217. According to the purpose, nutrient media of the "variegated series":
b) differential diagnostic
218. The purpose of stage III of the tank method:
c) pure culture identification
219. At the III stage of the tank method, the following is carried out:
e) selection of isolated colonies
220. The purpose of stage II of the tank method for isolating pathogens of anaerobic wound infections in the study of soil:
b) obtaining isolated colonies
221. Isolation of a pure culture of anaerobes is carried out according to the method:
b) Zeissler
222. Isolation of a pure culture of anaerobes is carried out according to the method:
b) Weinberg
223. Possible spore-forming pathogens of anaerobic infections in soil:
c) clostridia gas gangrene
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Obligate anaerobes are obviously an example of early anaerobic life forms. This is consistent with the theory of the origin of life on Earth, according to which the primary organisms of our planet were anaerobes. A comparative biochemical analysis leads to the conclusion that the energy metabolism of all organisms without exception is based on the same strikingly similar chains of reactions that are not associated with the consumption of free oxygen, - reactions that occur in the cells of modern anaerobes (according to A.I. Oparin).[ ...]
An obligate organism (from Latin - obligatory) is an organism strictly specialized to a certain type of nutrition, respiration, environmental factors (monophages, necrophages, aerobes, anaerobes, etc.).[ ...]
Anaerobe - an organism that can live in an oxygen-free environment. There are obligate anaerobes - permanently living in an oxygen-free environment and facultative - capable of living both without oxygen and in its presence (organisms of city sewers, primary sedimentation tanks, etc.).[ ...]
Obligate anaerobes - organisms that are unable to live in an oxygen environment (some bacteria).[ ...]
Obligate anaerobes include the genera Desulfovibrio, Desuljotomaculum, some species of the genus Bacillus. Bacilli are found among various ecological groups of microorganisms and adapt to any oxygen regime.[ ...]
In obligate aerobes and facultative anaerobes in the presence of oxygen, catabolism proceeds in three stages: preparatory, anoxic and oxygen. As a result, organic substances break down into inorganic compounds. In obligate anaerobes and facultative anaerobes, with a lack of oxygen, catabolism proceeds in the first two stages: preparatory and anoxic. As a result, intermediate organic compounds are formed that are still rich in energy.[ ...]
Spores of obligate mesophilic and thermophilic anaerobes - causative agents of bombing - in canned food before sterilization are determined: after registering an increased contamination of the product before sterilization - immediately, after registering a bacteriological defect, if the production of this type of canned food continues - immediately, preventive control, at least 1-2 times a week for each type of canned food from each line.[ ...]
The cytoplasm of anaerobes has a composition and structure similar to that of aerobes. The cytoplasm of some anaerobes contains inclusions of the reserve nutrient granulosa, a starch-like polysaccharide. On ultrathin sections, this substance can be seen in the form of light spherical inclusions (Fig. 45). Lipid bodies (drops of poly-p-hydroxybutyric acid) are rare in the cytoplasm of obligate anaerobes.[ ...]
These bacteria are also very sensitive to oxygen. Thus, the differences between obligate anaerobes and aerobes relate primarily to the enzymatic provision of terminal oxidation. In anaerobes, free oxygen cannot be used as the final hydrogen acceptor.[ ...]
Butyric acid bacteria are obligate anaerobes, that is, strict anaerobes. They are extremely widespread in nature: up to 90% of soil samples, as a rule, contain representatives of this group of bacteria.[ ...]
Green bacteria are strict anaerobes and obligate phototrophs. An exception are representatives of the genus Chloroflexis. They grow only under aerobic conditions, both in light and in the dark. However, even phototrophic bacteria that grow well in the dark develop better in the presence of light. Depending on the organism, the optimal lighting conditions for its growth may be different. Some species grow well in low light (100-300 lux), others in stronger light (700-2000 lux).[ ...]
A significant number of bacteria - obligate aerobes and facultative anaerobes - are able to exist due to the use of water pollution (impurities) as a source of nutrition. At the same time, part of the used organic substances is spent on energy needs, and the other part is spent on the synthesis of the cell body. Part of the substance consumed for energy needs is completely oxidized by the cell, i.e., to CO2, H2O, >N3. Oxidation products - the metabolite - are excreted from the cell into the external environment. The reactions of synthesis of cellular substance also take place with the participation of oxygen. The amount of oxygen required by microorganisms for the entire cycle of the reaction of synthesis and energy production is BOD.[ ...]
In addition to glycolysis, facultative anaerobes have other ways of anaerobic ATP generation associated with the decarboxylation of α-ketoglutaric and pyruvic acids, the elimination of their carboxyl groups, and the formation of CO2. This complex, multi-step chain of reactions has not yet been studied enough. But from all that has been said, it follows that the set of enzymes in the tissues of facultative anaerobes should, if not qualitatively, then at least quantitatively and in terms of the nature of activity regulation, differ significantly from what takes place in obligate aerobes, and allow them to draw energy from aerobic, and from anaerobic oxidative processes.[ ...]
When studying the effect of oxygen on the development of obligate anaerobes, it was shown that oxygen does not have a detrimental effect on anaerobes if the ORP of the environment is low. Indeed, if reducing agents that reduce ORP are added to the medium, then some anaerobic microorganisms are able to grow on such media under aerobic conditions. In general, anaerobes can be attributed to such microorganisms, the growth and development of which is confined to natural substrates that are deprived of free oxygen and have a low redox potential.[ ...]
According to Campbell and Postgate, all spore-forming anaerobes with a constant ability to reduce sulfates were isolated in a new genus - BeviHo-1; It includes obligate anaerobes with gram-negative, straight or curved rods that swell in thermophilic forms. Spores are formed terminally or subterminally. The composition of DNA ranges from 41.7-49.2 mol.% G + C.[ ...]
Most purple sulfur bacteria are strict anaerobes and obligate phototrophs, i.e., their growth is possible only under illumination. Only three species are known to grow in the presence of air, and not only in the light, but also in the dark, albeit slowly. These are A. roseus, E. shaposhnikovii and T. roseopersicina. All non-sulfur purple bacteria also grow under anaerobic conditions, but are mostly facultative aerobes. Until recently, it was believed that the growth of purple bacteria in the dark is possible only under aerobic or microaerophilic conditions, since in the absence of light they receive energy in the process of respiration. However, it has recently been established that R. rubrum and a number of representatives of Rhodopseudomonas grow in the dark and under strictly anaerobic conditions due to the fermentation of certain organic substrates. The purple sulfur bacteria E. shaposhnikovii and T. roseopersicina seem to have the same possibility.[ ...]
So, despite the fact that anaerobic saprophages, both obligate and facultative, make up a smaller part of the components of the community, they nevertheless play in the ecosystem. important role, since only they are capable of breathing in the oxygen-free lower tiers of the system deprived of light. By occupying these inhospitable habitats, they "save" energy and materials, making them available to most aerobes. Thus, what seems to be an "inefficient" way of breathing turns out to be an integral part of the "efficient" exploitation of energy and material resources by the ecosystem as a whole. For example, the efficiency of wastewater treatment, which is provided by a human-managed heterotrophic ecosystem, depends on the consistency between the activities of anaerobic and aerobic saprophages.[ ...]
The toxic effect of atmospheric oxygen on the growth and development of obligate anaerobes and the attraction to a low redox potential, according to modern ideas, can be explained by the fact that molecular oxygen and high ORP can cause irreversible oxidation of vital enzymes that determine the main processes of their metabolism.[ ...]
Methanobacterium omelianskii, Bad. formicicum, Methanosarcina barkeri are obligate anaerobes and are relatively difficult to isolate. Culture Bad. formicicum decomposes formic acid with the formation of various decomposition products, and the direction of the process depends on the redox potential of the medium. Under conditions of relative anaerobiosis, as established by JI. V. Omelyansky j formic acid decomposes with the formation of hydrogen and carbon dioxide; at the same time, the potential of the nutrient medium decreases to hH2 12-12.9 and anaerobic conditions are created. Upon decomposition under anaerobic conditions and a decrease in rH2 to 6-7, formic acid decomposes with the formation of methane; in the range of values hH2 16-22, the decomposition of formic acid occurs only with the formation of carbon dioxide.[ ...]
This chapter talks about spore-forming anaerobic bacteria, and only about obligate, that is, those organisms that are not able to develop under aerobic conditions, in contrast to facultative ones, capable of living both due to respiration, using molecular oxygen, and due to " nitrate respiration" or fermentation of various organic substances under anaerobic conditions. It should be noted that anaerobic spore-bearing bacteria are less studied than aerobic ones, due to significant difficulties, which researchers encounter when isolating and cultivating anaerobes.[ ...]
Genus Peptococcus. Cells solitary, in pairs, tetrads, aggregates. Obligate anaerobes with proteolytic activity and fermenting various organic compounds. The optimum temperature is 37 °C. The type species is Peptococcus niger, which produces a black pigment. They live in feces, dirt, in the human body and are capable of causing septic infections under certain conditions.[ ...]
Anaerobiosis is also characteristic of facultative anaerobic microorganisms. Unlike the latter, obligate anaerobes cannot develop in the presence of oxygen; moreover, oxygen in molecular form is poisonous to anaerobes.[ ...]
The results of six studies in which nine were used under anaerobic conditions different types obligate and facultative anaerobes growing on seven different substrates gave an average value of UCcal = 0.130 g/kcal.[ ...]
Microorganisms belonging to different taxonomic groups can oxidize molecular hydrogen. Among them there are strict anaerobes, facultative anaerobes and obligate aerobes. Facultative anaerobes and aerobes with this property include Escherichia coli, Paracoccus denitrificans, Streptococcus faecalis and some representatives: Bacillus, Pseudomonas, Alcaligenes, Acetobacter, Azotobacter, Mycobacterium, Nocardia, Proteus, as well as certain types blue-green and green algae.[ ...]
If we agree with the statement (quite convincingly substantiated by the data of comparative physiology and biochemistry) that obligate anaerobes are an example of early forms of life on Earth, then the question arises whether the origin and evolution of anaerobes were reflected in the composition and structure of their DNA - the guardian genetic information. It is now well known that deoxyribonucleic acids are only organic world a single structural plan is inherent, and on the other hand, there are unlimited possibilities for variations in the composition and structure of these compounds. It is quite logical to think that the emergence of DNA in the history of life on Earth was a very important and, probably, even a decisive factor in the differentiation and isolation of new groups and species of living beings. Since exactly nucleic acids are directly related to heredity and variability, then they should be the material basis of the evolutionary process.[ ...]
These results allow us to conclude that the leading role in the processes of anaerobic decomposition of organic material is played by obligate organisms. anaerobic bacteria. However, the systematic detection of aerobes and facultative anaerobes in the contents of digesters indicates that these microorganisms also participate in the destruction of organic substances, and under certain conditions their number can increase significantly. Thus, when glucose is added to the fermented liquid, the number of aerobic and facultative anaerobic bacteria increases from 1 X 10b to 3.2 X 109 cells / ml (quoted from ).[ ...]
When the treatment plant is overloaded with organic pollution, when the amount of incoming air is not enough, obligate (unconditional) or facultative anaerobes develop, for which oxygen is harmful.[ ...]
In the second phase of alkaline or methane fermentation, methane and carbonic acid as a result of the vital activity of methane-forming bacteria - non-spore-bearing obligate anaerobes, very sensitive to environmental conditions. The studied species of methane-forming bacteria belong to three genera: Methanobacterium, Methanococcus, Methanosarcina.[ ...]
Some anaerobic microorganisms use bound oxygen, which is part of compounds such as sulfates or nitrates, as an acceptor. In the presence of oxygen, they have aerobic respiration, and in oxygen-free environments they use the oxygen of nitrates as an acceptor, reducing them to nitrogen or its lower oxides. Bacteria that reduce sulfates to hydrogen sulfide in the process of respiration are obligate anaerobes, for example, VeviNowsh-gyu (keiUipcans.[ ...]
Different species and genera of bacteria are not equally related to adaptation. Some adapt faster to changing conditions, others slower. Bacteria of the genus Rseuiotopaz adapt better than others.[ ...]
But animals are known that can live equally normally both with a good availability of oxygen, and with an extremely low content of it, and with an almost complete absence, and even those that not only do not need oxygen, but are even harmful. The former are called facultative anaerobes, the latter are obligate. The former include aquatic turtles and many fish that lead a benthic lifestyle. The fact is that in the bottom water the oxygen content can reach up to 15% of the value that is observed when the water is saturated with air.[ ...]
The use of electron microscopy methods, which make it possible to study the distribution of dehydrogenases in whole cells, shows that dehydrogenases in anaerobic spore-bearing bacteria are obviously also associated with membranes, which play a huge role in living organisms, especially in the processes of energy metabolism. At the same time, in other anaerobes, the reduction of electron acceptors is also observed in the cytoplasm. Perhaps these phenomena are associated with a different set of enzymes in different species or with nonspecific reduction of dyes in the cytoplasm.[ ...]
The depletion of molecular oxygen in situ leads to a slowdown in heat release, and the supply of oxygen due to convection also decreases accordingly. At the same time, the accumulation of carbon dioxide during the composting stage creates microaerophilic conditions, which lead to an increase in the number of first facultative and then obligate anaerobes. In contrast to aerobic metabolism, in which the mineralization of waste is often achieved with the help of one type of bacteria, anaerobic biodegradation requires the joint metabolism of microorganisms of different species that are part of a mixed population. This population of microorganisms interacting with each other is able to use various inorganic electron acceptors, often in a sequence corresponding to the release of energy during this reaction. Since most bacteria require certain electron acceptors, this sequence leads to significant changes in the composition of the microbial population. Species that are able to use more oxidized acceptors gain thermodynamic and therefore kinetic advantages.[ ...]
So the transformation organic matter in metatanks, it occurs in two stages: fermentation of the substrate to fatty acids (non-methanogenic) and formation of CH4 and CO2 from fatty acids (methanogenic). During the first stage leading role Anaerobic bacteria of the genera Clostridium, Bacteroides, etc. play the second stage. The second stage is carried out by a unique group of obligate anaerobes - methane bacteria of the genera Methano-bacterium, Methanobacillus, Methanococcus, Methanosarcina.[ ...]
The presence of acids in the medium causes its acid reaction. In addition to SFA, the products of the decomposition of the first phase are lower fatty alcohols, amino acids, some aldehydes and ketones, glycerin, as well as carbon dioxide, hydrogen, hydrogen sulfide, ammonia and some other compounds. This phase of the process is carried out by bacteria belonging to facultative anaerobes (lactic acid bacteria, acetic acid, propionic acid, etc.) and obligate anaerobes (butyric acid bacteria, cellulose, acetonobutyl, etc.).[ ...]
Fermentation goes through the stages of formation of pyruvic acid with its subsequent transformation. The source of nitrogen for butyric bacteria is peptones, amino acids and ammonium salts, some of the bacteria also use free nitrogen. Carbohydrates serve as a source of energy and carbon for them. The causative agents of butyric fermentation are obligate anaerobes. These are large, mobile spore-forming rods 3-10 microns long and 0.5-1.5 microns in diameter. The optimum temperature for their development is 35-37°C, pH limit values are 6-8.[ ...]
Photosynthetic bacteria are mainly aquatic (marine and freshwater) organisms; in most cases they play an insignificant role in the production of organic matter. But they are able to function in conditions that are generally unfavorable for most green plants, and in water sediments they participate in the cycle of some elements. For example, green and purple sulfur bacteria play an important role in the sulfur cycle (see Figure 4.5). These obligate anaerobes (capable of life only in the absence of oxygen) are found in the boundary layer between the oxidized and reduced zones in sediments or water, where light hardly penetrates. These bacteria can be observed in littoral silt, where they often form distinct pink or purple layers directly below the upper green layers of algae living in the silt (in other words, at the uppermost limit of the anaerobic, or reduced, zone, where there is light but little oxygen) . In a study of Japanese lakes (Takahashi and Ichimura, 1968), it was calculated that the share of photosynthetic sulfur bacteria in most lakes accounts for only 3-5% of the total annual production of photosynthesis, but in stagnant lakes rich in H2S, this share rises to 25%. Non-sulfur photosynthetic bacteria, on the contrary, are usually facultative aerobes (able to function both in the presence and in the absence of oxygen). In the absence of light, they, like many algae, can behave as heterotrophs. Thus, bacterial photosynthesis can be useful in polluted and eutrophic waters, in connection with which its study is now intensifying, but it cannot replace "real" photosynthesis with the release of oxygen, on which all life on Earth depends.[ ...]
Free-living diazotrophs are most vulnerable to erosion of arable land. At the first stages of degradation, the mechanisms of anaerobic nitrogen fixation are rapidly suppressed due to a decrease in the amount of the labile part of organic matter (Khaziev, 1982; Khaziev and Bagautdinov, 1987). The pool of diazotrophs is extremely sensitive to the carbon substrate. Obligate anaerobes of the genus Clostridium, in contrast to aerobic forms functioning on a wide range of C compounds, including humic and fulvic acids, use a narrow carbohydrate flow (Klevenskaya, 1974; Mishustin and Emtsev, 1974). The diverse composition of the carbohydrate fund of the soils of the chernozem series of Western Siberia (Klevenskaya, 1991) provides a sufficient energy and trophic level of clostridia, contributing to their certain predominance in soils unaffected by erosion. The transformation of the microbial community intensifies with the development of erosion on the slope of the southern exposure, where, as is known, the thickness of the humus horizon is less in comparison with the northern counterparts, and the processes of mineralization of organic matter and nitrogen are more intense (Chuyan, Chuyan, 1993).[ ...]
The formation of the microflora of the digester occurs due to microorganisms that have fallen along with sewage or sediment. In terms of species composition, the biocenosis of digesters is much poorer than aerobic biocenoses, of which only about 50 species of bacteria have been isolated that are capable of carrying out the first stage of splitting pollution - the stage of acid formation. Along with obligate anaerobes, facultative anaerobes can also be found in the digester. The total number of bacteria in the sediment ranges from 1 to 15 mg/ml. The end product of the fermentation process of this group of microorganisms are lower fatty acids, carbon dioxide, ammonium ions, hydrogen sulfide.[ ...]
FEEDING AREA (waters) - region. inflow of precipitation, surface or groundwater into the aquifer (ST SEV 2086-80). UNLOADING AREA (water) - region. groundwater outlets to the surface of the earth, into reservoirs or watercourses, as well as their overflow into adjacent aquifers (ST SEV 2086-80). See Unloading. Afforestation - restoration or creation of forest areas by sowing seeds of woody plants, planting their seedlings or promoting natural reforestation (eg, in the development of spoil heaps). See reforestation. OBLIGATORY ORGANISM [from lat. obligatory] - an organism strictly specialized for a certain type of nutrition, respiration, environment (monophages, anaerobes, etc.).[ ...]
These microbes got their name for their ability to rapid oscillatory movements (from the Latin "vibrare" - to oscillate). Vibrios are shaped like short, comma-shaped sticks. After division, they often remain linked ends, forming spirals. They are unable to break down fiber. Many use phenols and other cyclic compounds. The length of individual vibrios rarely exceeds 10 microns, and their diameter is from 1 to 1.5 microns. Some of them are strict anaerobes, others are obligate aerobes or facultative anaerobes (growing in the presence of oxygen and at a reduced concentration of it). These are mainly saprophytes, widespread in polluted rivers and lakes of our planet.[ ...]
During biological oxidation, redox reactions occur, accompanied by the removal of hydrogen atoms from some compounds (donors) and its transfer to others (acceptors), or reactions associated with the transfer of electrons from a donor to an acceptor. These processes are carried out with the participation of enzymes belonging to the class of oxidoreductases. Respiration processes in which molecular oxygen is an acceptor of hydrogen or electrons are called aerobic. If the acceptors are other inorganic or organic compounds, then this type of respiration is called anaerobic. According to the type of respiration, two groups of microorganisms are distinguished: aerobes (oxybiotic forms), which require oxygen for respiration, and anaerobes (anoxibiotic forms), which develop in the absence of oxygen. There is no sharp difference between them. Along with strict (obligate) aerobes and anaerobes, there are microorganisms that can live in the presence of oxygen and without it. These are microaerophiles, the optimum oxygen content in the air for which is 0.5-1%, and facultative anaerobes. So, Escherichia coli is a facultative anaerobe.
obligate anaerobes are, obligate anaerobes are representativesObligate (strict) anaerobes- organisms that live and grow only in the absence of molecular oxygen in the environment, it is detrimental to them.
Metabolism
It is widely believed that obligate anaerobes die in the presence of oxygen due to the absence of the enzymes superoxide dismutase and catalase, which process the deadly superoxide formed in their cells in the presence of oxygen. Although in some cases this is true, nevertheless, activity of the aforementioned enzymes has been found in some obligate anaerobes, and genes responsible for these enzymes and related proteins have been found in their genomes. Such obligate anaerobes include, for example, Clostridium butyricum and Methanosarcina barkeri. Yet these organisms are unable to exist in the presence of oxygen.
There are several other hypotheses to explain why strict anaerobes are sensitive to oxygen:
- Decomposing, oxygen increases the redox potential of the environment, and a high potential, in turn, inhibits the growth of some anaerobes. For example, methanogens grow at a redox potential of less than -0.3 V.
- Sulfide is an integral component of some enzymes, and molecular oxygen oxidizes sulfide to disulfide and thereby disrupts the activity of the enzyme.
- Growth can be inhibited by the lack of electrons available for biosynthesis, since all the electrons go to reduce oxygen.
It is most likely that the sensitivity of strict anaerobes to oxygen is due to these factors in combination.
Instead of oxygen, obligate anaerobes use alternative electron acceptors for cellular respiration, such as: sulfates, nitrates, iron, manganese, mercury, carbon monoxide (CO). For example, sulfate-reducing bacteria, which are found in large numbers in the bottom marine sediments, cause the smell of rotten eggs in these places due to the release of hydrogen sulfide. The energy released by such breathing processes is less than by oxygen respiration, and the above alternative electron acceptors do not provide an equal amount of energy.
Representatives
Bacteroides and Clostridium are examples of non-spore-forming and spore-forming strict anaerobes, respectively.
Other examples of obligate anaerobes are Peptostreptococcus, Treponema, Fusiform, Porphyromonas, Veillonella and Actinomyces.
Notes
- Kim, Byung Hong and Geoffrey Michael Gadd. Bacterial Physiology and Metabolism. Cambridge University Press, Cambridge, UK. 2008.
- ANAEROBIC BACILLI (inaccessible link - history). Retrieved March 10, 2009. Archived from the original on January 29, 2009.
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obligate anaerobes and, obligate anaerobes representatives, obligate anaerobes are
