Bacteria: a way of a food, features of a structure, an inhabitancy
In our article the most ancient organisms - bacteria will be considered. The diet and habitat of these organisms are very diverse. How are these characteristics interrelated?
General characteristics of bacteria
Bacteria are a group of unicellularmicroscopic organisms. They are prokaryotes. This means that their cells do not contain a formed nucleus. Their genetic material is represented by a circular DNA molecule located directly in the cytoplasm.
Forms of bacterial cells are distinguished by a largediversity. They can look like a ball, rods, bunches of grapes, spirals, sprouts, cube, etc. The surface apparatus of bacteria is represented by a permeable membrane, a mucous capsule and a cell wall consisting of murein or pectin. The cytoplasm of prokaryotes contains ribosomes and cytoskeleton elements.
Bacteria: diet and habitat
Thanks to the simplicity of the structure, the bacteria have mastered everythinghabitat. They are found in water, soil, air, rocks, hot springs, on the surface of the body, in the internal organs of plants, animals and humans. By way of nutrition, bacteria are both auto- and heterotrophs.
The first contain plastids in their cellschloroplasts, due to which photosynthesis is carried out. As a result, a glucose carbohydrate is formed, which is used to carry out various vital processes. Organisms that use solar energy for the synthesis of organic substances are also called phototrophs. These include green, purple and cyanobacteria.
Another group of autotrophic bacteria usesvital energy of chemical bonds. They convert complex compounds into simpler ones. This process is called chemosynthesis. Examples of such organisms are sulfur-, iron- and nitrogen-fixing bacteria.
A group of heterotrophic prokaryotes is also quite numerous. The source of their food depends on the environment. Depending on this, three groups of bacteria are distinguished:
- symbiotic organisms.
Let's consider each of them in more detail.
This group of bacteria lives in all environments,which contain organic substances. It can be soil, plant and animal organisms. For example, rotting bacteria by diet are saprotrophs. They decompose organic matter, extracting nutrients from it.
This is also the method of feeding lactic acid bacteria. Their ability to ferment carbohydrates is widely used in the food industry. Kefir, fermented baked milk, cottage cheese, yoghurt - all these are the products of vital activity of prokaryotes of this species.
Parasitic bacteria, a method of feeding whichalso heterotrophic, live inside or on the surface of other organisms. Feeding on the products of the life of the owners, they cause serious diseases. For example, a dysenteric rod that multiplies in the intestines, causes weakness, fever, headache, and upset of the stool are all manifestations of dysentery. "Disease of dirty hands" is often called salmonellosis, typhoid and cholera. All of them are caused by ingestion of parasitic prokaryotes into the body.
Dangerous diseases of humans and animals are tuberculosis, anthrax, tetanus, tonsillitis, diphtheria, glanders, brucellosis. The mechanisms of their entry into the body are different:
- the use of contaminated water or products;
- airborne droplet path;
- non-compliance with hygiene.
Many organisms are able to enter intomutually beneficial relationships with representatives of other kingdoms of living nature. Bacteria are no exception. The diet of representatives of this group is also heterotrophic. However, they feed on ready-made substances of other organisms, without harming them. In addition, such cohabitation has many benefits.
An example of such a manifestation areNitrifying bacteria that live in the roots of leguminous plants. Getting there from the soil through the cracks of the cover cloth, they begin to multiply actively. As a result, small but numerous bubbles form. This type of microorganism is able to fix nitrogen, which is part of the air, and convert it into a form that is accessible to plants. Thus from plants they receive nutrients which are in an aqueous solution.
The symbiotic bacteria of humans areprokaryotes living in its intestines. Here they produce enzymes that further promote the cleavage of a number of organic compounds. Bacteria of the skin and mucous membranes prevent the dispersal of "alien" prokaryotes.
So, bacteria are unicellular prokaryotic organisms. They can both independently synthesize organic substances (autotrophs), and eat ready (heterotrophs).