What is bacteria, and what is their role in nature

Approximately from the end of the XIX century, scientists began to accumulate knowledge about the differences between the pro- and eukaryotic cells and so gradually isolated a separate kingdom of microorganisms, united by the absence of cell differentiation, - Protista. However, what are bacteria, at that time they only had to study: only in the XX century. This knowledge has been systematized. Bacteria are located in all environments where organic matter can accumulate. They tolerate high and low temperatures, salinity and acidity. So, the realm of bacteria lives not only in the environment, where they decompose organic matter for their life, but also densely populates many mucous membranes of animals and humans, helping to digest food and competing with pathogenic microorganisms. Their role in the exchange of nitrogen is especially great, since only cyanobacteria are able to process atmospheric nitrogen. However, some bacteria are the causative agents of diseases: plague, anaerobic and intestinal infections, syphilis, cholera and anthrax.

Morphology

Ultrasound of bacteria is seen only on an electron microscope, but what bacteria are and how they look from the outside can be discerned with immersion microscopy using special methods of coloring. The sizes of these microorganisms vary from 0.1 to 10 μm, but the morphology of bacteria allows them to be divided into 3 main groups: globular - cocci (mono-, diplo-, tetra-, streptococci and sarcin), rod-shaped - bacilli (mono-, , Strepto-) and convoluted - vibrios, spirillae and spirochetes. In laboratory conditions, to determine the type and enzymatic properties, they are grown on simple or special nutrient media by the formation of colonies, and in different environments they also have a different growth pattern.

Structure

In general, what is bacteria determines their ultrastructure. Outside, the bacteria are protected by a cell wall consisting of layers of peptidoglycan, lipids and teichoic acids. The concentration of the first determines the ability of bacteria to stain by the Gram method in the smear, according to which they are classified into Gr + and Gr-. Some of them have an additional protective structure - a capsule containing K-antigen and preventing their phagocytosis inside the macroorganism, the action of toxic and mechanical factors. To learn more about what bacteria are, you need to study their intracellular structure: the bacteria are filled with the cytoplasm, in which other organelles (ribosomes, chromatophores) are dissolved and nutrients (lipids, sugars) are included. They, like all prokaryotes, do not have a formed nucleus, and all genetic information is stored in a double-stranded nucleic acid molecule located in the nucleoid zone and fixed to the membrane at one point. Outside its genetic information lies in the plasmids, which can determine the development of pathogenic properties and factors. For the movement, they use flagella and spirillae, fixed in the cell basal body, and their reproduction occurs by dividing in two.