Aerobic bacteria are microorganisms that require free oxygen for normal life. Unlike all anaerobes, they also participate in the process of producing the energy they need to reproduce. These bacteria do not have a pronounced nucleus. They multiply by budding or dividing and form various toxic products of incomplete reduction during oxidation.
Features of aerobics
Not many people know that aerobic bacteria (in simple terms, aerobes) are such organisms that can live in the soil, in the air, and in the water. They actively participate in the circulation of substances and possess several special enzymes that ensure their decomposition (for example, catalase, superoxide dismutase and others). Respiration of these bacteria is carried out by direct oxidation of methane, hydrogen, nitrogen, hydrogen sulfide, iron. They can exist in a wide range at a partial pressure of 0.1-20 atm.
Cultivation of aerobic gram-negative and gram-positive bacteria implies not only the use of a suitable nutrient medium, but also the quantitative control of the oxygen atmosphere and the retention of optimal temperatures. For each microorganism of this group there is a minimum and a maximum of oxygen concentration in the environment surrounding it, necessary for its normal reproduction and development. Therefore, both the reduction and increase in the oxygen content beyond the "maximum" lead to the cessation of the vital activity of such microbes. All aerobic bacteria die at an oxygen concentration of 40 to 50%.
Types of aerobic bacteria
By the degree of dependence on free oxygen, all aerobic bacteria are divided into these types:
1. Obligatory aerobes are "unconditional" or "strict" aerobes that can develop only when there is a high concentration of oxygen in the air, since they receive energy from oxidative reactions with its participation. These include:
- some types of pseudomonads;
- many saprophytes;
- diphtheria rods;
- cholera vibrio;
- tubercle bacillus;
- causative agents of tularemia .
2. Optional aerobes are microorganisms that develop even at very low levels of oxygen. This group includes:
- yeast rod;
- most pathogenic microbes ( meningococci , gonococci).
When they get into the usual external environment, such bacteria almost always die, because a large amount of oxygen has a negative effect on their enzymes.