Decompose organic matter into inorganic matter and return it to Inorganic environment The process of releasing energy is called alienation. The essence of alienation is macromolecules in organisms, including proteins lipid and Sugar It is oxidized and releases energy in the process of oxidation. Part of the energy is ADP conversion by ATP ATP is used as energy storage material for other needs. In short, assimilation It is to turn non self into self; On the contrary, alienation turns itself into non self. Assimilation is an important process in metabolism, which is the process of recombining digested nutrients to form organic matter and store energy. Cell respiration is the most basic dissimilation in the biological world. It releases energy by oxidizing and decomposing organic matter, and provides direct energy material ATP for biological life activities. Cell respiration can be divided into aerobic respiration and anaerobic respiration according to whether oxygen is needed. However, some organisms or tissues can carry out aerobic respiration or anaerobic respiration, and can also carry out aerobic respiration and anaerobic respiration at the same time, such as yeast. [1]
The types of alienation include Aerobic 、 Anaerobic type And facultative anaerobic type. Most animals and plants need to live in an oxygen rich environment. In the process of alienation, they must constantly absorb oxygen from the outside environment to oxidize and decompose organic substances in their bodies, and release the energy in order to maintain their own life activities. This type of metabolism is called aerobic or aerobic. During aerobic dissimilation, sugars, lipids, proteins, etc. become compounds containing carboxyl groups and undergo decarboxylation enzymatic reaction to generate carbon dioxide; Hydrogen is activated by dehydrogenase in the mitochondria and gradually releases energy by reducing the substrate through the transmission of respiratory chain, and is oxidized to generate water. [4]
This type of organism includes a few animals, such as lactic acid bacteria and parasites living in animals. They can still oxidize organic substances in their bodies under the condition of hypoxia, from which they can obtain the energy needed to maintain their own life activities. This type of metabolism is called anaerobic or anaerobic respiration. Anaerobic dissimilation lacks oxygen, an oxidant, which can not completely decompose macromolecules and release their energy. [4]
Facultative anaerobic type
This kind of organism carries out aerobic respiration under the condition of sufficient oxygen to completely decompose organic matter into carbon dioxide And water, under the condition of hypoxia, the organic matter is not completely decomposed into lactic acid or alcohol and water. The typical facultative anaerobic organism is yeast. The metabolism of yeast, like many microorganisms, includes the increase or accumulation of energy (alienation) and the consumption or biosynthesis of energy (assimilation). These processes include the transfer of simple atoms, atomic clusters or electrons. Growth is the balance of these redox reactions. Some of the energy released by dissimilation can be used to promote the synthesis of proteins and other substances needed by cells. Yeast is widely used in production. In addition to the well-known wine making and dough making, it can also be used to produce organic acids and extract a variety of enzymes.
Methylotrophic bacteria The dissimilation pathway of formaldehyde metabolism is to combine formaldehyde with C1 carrier and oxidize it to intermediate formic acid through coenzyme factors spontaneously or under the catalysis of enzyme Formate dehydrogenase Oxidation to CO under the action of two 。 The dissimilation pathways of methylotrophic bacteria to metabolize formaldehyde include tetrahydrofolate pathway (THF), tetrahydromethotrexate pathway (H4MPT) glutathione (GSH/MySH) pathway, involving key enzymes and their coding genes. Further study on formaldehyde dissimilation pathway, key enzymes, genes and their functions is the key to construct formaldehyde purification engineering bacteria and develop formaldehyde purification transgenic plants. [2] 
