Anaerobic Respiration
Anaerobic respiration is a metabolic process that occurs in the absence of oxygen, producing energy for cells. It involves the breakdown of glucose into pyruvate, followed by the conversion of pyruvate into other compounds such as lactic acid or ethanol, releasing energy in the form of ATP. This process is less efficient than aerobic respiration but is essential for organisms in low-oxygen environments.
7 Key excerpts on "Anaerobic Respiration"
eBook - ePubBiology
A Self-Teaching Guide
- Steven D. Garber(Author)
- 2020(Publication Date)
- Jossey-Bass(Publisher)
...When we run so fast that our muscles don't get enough oxygen, they keep working without oxygen, using an anaerobic reaction, that creates energy, but the process produces lactic acid as a metabolite. Metabolites are produced, often as end products, due to metabolic processes. Metabolic processes are part of an organism's metabolism. The term metabolism refers to the chemical processes inside living organisms that sustain life. ANAEROBIC FERMENTATION Many cells, particularly those in most plants and in some microorganisms, can obtain energy without oxygen by the anaerobic process of fermentation (also called Anaerobic Respiration). Without oxygen, the pyruvate will accept hydrogen from NADH 2, freeing more NAD to accept hydrogen in other glycolytic reactions. When added to the pyruvate, the hydrogen will convert it into ethyl alcohol, a 2-carbon compound, and release carbon dioxide in the process. This anaerobic pathway converts pyruvate into alcohol (ethanol). In animals and some microorganisms, Anaerobic Respiration reduces (adds hydrogen to) pyruvate, producing energy and lactic acid (lactate is a 3-carbon compound). The anaerobic processes that form ethanol or lactate are called fermentation. For an illustration of them, see Figure 5.7. If the energy released through a series of controlled glycolytic steps were released at once, the heat could cause a fire. This explains why cells use small, incremental steps, each releasing controlled energy either to synthesize ATP or to help attach hydrogen atoms to molecules of the hydrogen-carrying coenzyme NAD + (nicotinamide adenine dinucleotide) to form NADH 2. Figure 5.7 Anaerobic conversion of pyruvate (pyruvic acid) to ethanol and to lactate (lactic acid). This process is also called Anaerobic Respiration and alcoholic fermentation. The enzymes that engage each glycolytic step are dissolved in the cytoplasm. For other carbohydrates to enter the glycolytic pathway, they too must first be converted to glucose...
eBook - ePub- Volodymyr Ivanov(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...22 Anaerobic and Anoxic Biotreatment of Waste Oxygen and Energy Generation The evolution of an anaerobic to an aerobic atmosphere on Earth resulted in the creation of the following: anaerobic (living without oxygen) microorganisms facultative anaerobic (living under either anaerobic or aerobic conditions) microorganisms microaerophilic (living under low concentrations of dissolved oxygen) microorganisms obligate aerobic (living only in the presence of oxygen) microorganisms Anaerobes produce energy from the following: fermentation (destruction of organic substances without an external acceptor of electrons) Anaerobic Respiration using electron acceptors such as N O 3 −, N O 2 −, Fe 3+, SO 4 2 −, and CO 2 anoxygenic (H 2 S → S) photosynthesis Microaerophiles and aerobes produce energy from the following: aerobic oxidation of organic matter oxygenic photosynthesis The sequence of increasing the production of biological energy per mole of transferred electrons is as follows: fermentation → CO 2 respiration (“hydrogenotrophic methanogenesis”) → dissimilative sulfate-reduction → dissimilative iron. reduction (“iron respiration”) → nitrate respiration (“denitrification”) → aerobic respiration. Anaerobic Digestion of Organic Matter There are many applications of anaerobic processes to the treatment of polluted soil, solid waste, and wastewater...
eBook - ePubMitochondria and Anaerobic Energy Metabolism in Eukaryotes
Biochemistry and Evolution
- William F. Martin, Aloysius G. M. Tielens, Marek Mentel(Authors)
- 2020(Publication Date)
- De Gruyter(Publisher)
...This is because when demand for ATP exceeds the amount that can be covered by aerobic respiration, the organism starts anaerobic production of ATP through substrate-level phosphorylation, which is the only form of ATP production when glucose is degraded to lactate via glycolysis. The concept of sufficient O2is noteworthy in its own right though, because what starts out as 21% O2in the air inhaled into a human lung drops to about 1% O2in our mitochondria.Metabolic repression is another physiological process that various species use for protection during hypoxic and anoxic periods. In this case, however, focus is on the rate of ATP consumption rather than its synthesis. During metabolic repression, energy metabolism is heavily slowed down in order to reduce the consumption of ATP, thereby limiting the need of its synthesis. Metabolic repression has been observed in invertebrates as well as vertebrates, mostly in marine animals that dive following inhalation, such as earless seals and sea turtles (Hochachka et al. 1996).3A modern context of atmospheric evolutionThe evolution of eukaryotic anaerobes needs to be seen in the context of Earth’s history. In particular, the availability of O2in the Earth’s history sets the scene for appreciation of eukaryote anaerobe evolution. A search of the literature for papers on the evolution of eukaryotic anaerobes will return a large number of contributions. At the time we write this book, there are two main schools of thought about the evolution of eukaryotic anaerobes. One view has it that eukaryotic anaerobes have preserved ancient biochemical relicts of the evolutionary past. That is our view. The alternative view is that eukaryotic anaerobes are recently arisen newcomers on the stage of evolution, an interpretation that is usually based on evidence from branching patterns in gene trees usually involving lateral gene transfer (for the interested reader, the exchange betweenMartin (2017c)andLeger et al...
eBook - ePubHandbook of Enology, Volume 1
The Microbiology of Wine and Vinifications
- Pascal Ribéreau-Gayon, Denis Dubourdieu, Bernard B. Donèche, Aline A. Lonvaud, John Towey(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
...Relationships of microorganisms with oxygen are diverse. Some microorganisms cannot use oxygen as the final acceptor and do not survive in its presence. Other microorganisms are also anaerobic, but oxygen has no effect on them. Some operate under aerobic conditions or anaerobic conditions but with different metabolic pathways depending on conditions. The latter microorganisms strictly depend on whether oxygen is present or not. Under aerobic conditions, the electrons and protons are transported to oxygen, which is reduced to water. This process is called aerobic respiration. The transport system consists of a group of cytochromes. The proton flux creates a proton motive force, which enables the synthesis of ATP molecules. The conservation of the oxidation energy is ensured by the synthesis of the pyrophosphate bond of ATP. This bond generates energy when it is hydrolyzed. This system does not exist in lactic acid bacteria, although some species can synthesize cytochromes from precursors. It characterizes acetic acid bacteria (Chapter 7). Some lactic acid bacteria reduce oxygen from the environment by forming hydrogen peroxide according to the following reaction: Hydrogen peroxide must be eliminated since it is a toxic molecule. Cells that are not capable of eliminating it cannot develop in the presence of oxygen: they are strict anaerobes. Depending on their behavior with respect to oxygen, lactic acid bacteria are classified as strict anaerobes, facultative anaerobes, microaerophiles, or aerotolerant anaerobes. The distinction between these different categories is often difficult to establish for a given strain. Most lactic acid bacteria tolerate the presence of oxygen but do not use it in energy‐producing mechanisms. Depending on the species, they use different pathways to eliminate the toxic peroxide, activating peroxidases that use NADH as a reducer, a superoxide dismutase, a pseudocatalase, and sometimes Mn 2+ ions (Desmazeaud and de Roissart, 1994)...
eBook - ePub- Rajeev Singh, Vishal Prasad, Barkha Vaish, Rajeev Pratap Singh, Vishal Prasad, Barkha Vaish(Authors)
- 2019(Publication Date)
- CRC Press(Publisher)
...2016; Mondal et al. 2017). This phenomenon prompts high-energy yields and a huge creation of sludge, because of high development of bacteria under oxygen consuming conditions (Xia et al. 2017). Anaerobic absorption is a biochemical procedure amid which complex organic matter is decayed without oxygen, by different sorts of anaerobic microorganisms. The procedure of anaerobic absorption is appropriate for all waste water treatment frameworks given that the solid can be acquainted with the framework at an adequate concentration (Świątczak et al. 2017). Biogas, a result of the anaerobic absorption process, is a perfect and sustainable type of energy which can be a substitute for regular wellsprings of energy that are causing ecological environmental issues and in the meantime exhausting at a quicker rate (Scarlat et al. 2018). Anaerobic wastewater purging procedures have been progressively utilized over the last couple of decades. These procedures are essential since they have constructive outcomes: expulsion of higher organic stacking, low sludge creation and high pathogen evacuation, methane gas generation, and low-energy utilization (Mrowiec and Suschka 2009; Castellano-Hinojosa 2018). As opposed to anaerobic digestion process, aerobic sludge assimilation is a less perplexing procedure that is utilized by numerous small networks. This chapter deals with the anaerobic and aerobic procedure and its complexities, covers the diverse stages engaged with the procedure, the substrate utilized all the while, and the connection between the substrate and the microorganisms. 6.2 PRINCIPAL POLLUTANTS OF WASTE 6.2.1 O RGANIC M ATERIAL The measure of putrescible natural material in sewage is demonstrated by the BOD; the more natural material there is in the sewage, the higher the BOD, which is a measure of the oxygen required by the microorganisms to decay natural substances present in sewage (Deblonde et al. 2011)...
eBook - ePubAnaerobic Waste-Wastewater Treatment and Biogas Plants
A Practical Handbook
- Joseph Chukwuemeka Akunna(Author)
- 2018(Publication Date)
- CRC Press(Publisher)
...Seventy percent of methane produced is from acetic acid by acetoclastic methanogenic bacteria, making it the most important substrate for methane formation (Mata-Alvarez 2003). Thirty percent is then produced from carbon dioxide and hydrogen by hydrogenophilic (or hydrogenotrophic) methanogenic bacteria. A simplified representation of the biochemical processes is given in Equations 1.1 and 1.2 ; the former representing hydrolysis and acidogenesis, and the latter representing acetogenesis and methanogenesis. Organics + nutrients → Volatile acids + alcohols + H 2 + CO 2 + H 2 S + NH 3 + cells (1.1) Volatile acids + alcohols + H 2 + CO 2 + nutrients → CH 4 + CO 2 + cells. (1.2) Table 1.1 shows a typical composition of gaseous by-products of functional anaerobic treatment process. Some of the common key microorganisms associated with different stages of the process are listed in Table 1.2. In the absence of microbial inhibition, the distribution and balance of these microbial groups in any anaerobic biological processes system will depend on the nature of the available the substrates and the environmental conditions (e.g., pH, temperature, potential redox, etc.). Anaerobic microorganisms can be suspended or can take the form of biofilm. Biofilm systems utilize various types of organic and inorganic materials as support media. They are able to retain a greater amount of biomass, and are generally more effective than suspended growth systems in wastewater treatment and hence are referred to as high-rate systems. TABLE 1.1 Typical Biogas Composition of a Functional Anaerobic Treatment Process TABLE 1.2 Anaerobic Digestion Stages and Typical Associated Microbial Species In anaerobic wastewater treatment, biomass produced during treatment must be separated from the treated wastewater before disposal or further treatment. The selection of suitable solid separation methods will depend on the process type and the desired treated effluent quality...
eBook - ePub- Jay Cheng, Jay Cheng(Authors)
- 2017(Publication Date)
- CRC Press(Publisher)
...The technology has also been used for the treatment of high-strength industrial wastewaters such as food processing, brewery, winery, dairy, and swine wastewaters. Compared to aerobic processes that are commonly used for municipal wastewater treatment, the main advantages of anaerobic technology are its low-energy requirement and operational cost. In addition, anaerobic digestion converts the organics in wastes into biogas that can be utilized for energy generation. Recovery of energy from waste treatment would offset the cost of the digester operation. A disadvantage of anaerobic digestion compared to aerobic treatment is that the growth of anaerobic microorganisms is very slow so a larger volume or longer hydraulic retention time (HRT) is required for the anaerobic digesters. To improve the efficiency of the anaerobic digestion, researchers and engineers have developed high-performance anaerobic reactors such as anaerobic packed-bed (APB) reactor, anaerobic fluidized-bed reactor, and upflow anaerobic sludge blanket (UASB) reactor. In these anaerobic processes, concentrated anaerobes are attached to the media or the biological granules in the reactors. HRT is uncoupled with the solid residence time (SRT), and HRT can be significantly reduced compared to the conventional suspended-growth anaerobic digestion process. 6.2 Anaerobic Process for Biogas Production Anaerobic digestion to convert organic compounds into biogas is a complex process that involves a series of microbial metabolism. The process can be divided into four main steps: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Each of the four steps involves different biochemical reactions with different substrates and microorganisms. Hydrolysis : Original organic waste materials usually contain mainly large-molecule compounds such as carbohydrates, proteins, lipids, and celluloses...
