Anaerobic bacteria can develop in the absence of free oxygen in the environment. Together with other microorganisms possessing a similar unique property, they make up the class of anaerobes. There are two types of anaerobes. Both facultative and obligate anaerobic bacteria can be found in almost all samples of material of a pathological property, they accompany various purulent-inflammatory diseases, can be opportunistic and even sometimes pathogenic.
Optional anaerobic microorganisms exist and multiply in both oxygen and oxygen-free environments. The most pronounced representatives of this class are Escherichia coli, Shigella, Staphylococcus, Yersinia, Streptococcus and other bacteria.
Obligatory microorganisms cannot exist in the presence of free oxygen and die from its effects. The first group of anaerobes of this class is represented by spore-forming bacteria, or clostridia, and the second group of bacteria that do not form spores (non-clostridial anaerobes). Clostridia are often the causative agents of anaerobic infections of the same name. An example would be clostridial wound infection, botulism, tetanus. Non-clostridial anaerobes are gram-positive and gram-negative bacteria. They have a rod-shaped or spherical shape, for sure you have come across the names of their brightest representatives in the literature: bacteroids, waillonella, fusobacteria, peptococci, propionibacteria, peptostreptococci, eubacteria, etc.
Non-clostridial bacteria in their bulk are representatives of the normal microflora in humans and animals. They can also participate in the development of purulent-inflammatory processes. These include: peritonitis, pneumonia, lung and brain abscess, pleural empyema, sepsis, maxillofacial phlegmon, otitis media, etc. For the bulk of infections that cause non-clostridial anaerobic bacteria, it is typical to exhibit endogenous properties. They develop mainly against the background of a decrease in the body's resistance, which can occur as a result of trauma, cooling, surgical intervention, and violation of the immune system.
To explain the method of maintaining the life of anaerobes, it is worth understanding the basic mechanisms by which aerobic and anaerobic respiration occurs.
Aerobic respiration is an oxidative process based on the use of oxygen. Breathing leads to the cleavage of the substrate without residue, the result is inorganic matter split into energy-poor ones. The result is a powerful release of energy. Carbohydrates act as the most important substrates for respiration, but proteins and fats can be consumed during aerobic respiration.
Two stages of the course correspond to it. The first is an oxygen-free process of gradual cleavage of the substrate to release hydrogen atoms and binding to coenzymes. The second, oxygen phase, is accompanied by a further cleavage of hydrogen atoms from the substrate for respiration and its gradual oxidation.
Anaerobic respiration is used by anaerobic bacteria. They use not molecular oxygen, but a whole list of oxidized compounds to oxidize the respiratory substrate. They can be salts of sulfuric, nitric, carbonic acids. During anaerobic respiration, they turn into reduced compounds.
Anaerobic bacteria carrying out such respiration as the final electron acceptor do not use oxygen, but inorganic substances. According to their belonging to a certain class, several types of anaerobic respiration are distinguished: nitrate respiration and nitrification, sulfate and sulfur respiration, “iron” respiration, carbonate respiration, fumarate respiration.