Bacteria are tiny, microscopic organisms that are not visible to the naked eye. They do not have a core shell limited. There are more than 3,000 species of such microorganisms in modern science, among which a wide segment is occupied by bacilli. The bacillus is a rod-shaped bacterium. And its name directly indicates the appearance (Latin: bacillum - stick). These bacteria were named by the German scientist W. Cohn in their shape resembling a stick.
Bacteria
What in bacteriology is understood by the generic name "bacillus"? This is a fairly extensive genus of gram-positive bacteria of a characteristic form. And first of all, in addition to their appearance, they are united by the ability to form intracellular spores, which serve for reproduction and preservation of the species in adverse conditions. Not all, but some of the bacilli cause diseases and toxic infections in humans, which means they are pathogenic (we will talk more about them below). And many of these bacteria are saprophytes, mainly found in the soil.
Conventional classification
It should be noted that “bacillus bacteria" is a rather conditional classification. Today it is used in microbiology quite rarely. This convention is due to the fact that the shape of the bacilli is characteristic of many bacteria (except cocci, which have a rounded shape), and a great many microorganisms can be characterized in appearance as sticks. But still it is possible to determine some basic characteristics that generalize the genus.
Main characteristics
- Most bacilli are saprophytes. They transform organics into inorganic compounds as a result of their life.
- Tolerance to oxygen. For them, it is not poison, and many use it for respiration (aerobic).
- Bacilli carry out their activities through chemical reactions.
- These bacteria are mobile and carry the movement with the help of flagella.
- Virulence: many bacilli cause disease in the human body.
Associations
Many rod-shaped bacilli are grouped into several cells.
- Diplobacillus is a paired association, two bacterial cells are combined.
- Streptobacillus is a chain where several cells are combined into a group. So, for example, the anthrax stick has a very long chain of associations in the form of curly threads.
Disputes
A bacillus is a bacterium that can form spores. Such spore formation may be one of the most obvious signs for classification. Moreover, the shape of the bacilli changes from the position of the spores in the bacterial cell. In tetanus sticks, for example, spores are knocked down at the ends of cells, giving them the appearance of drumsticks (clostridia). And in oily bacilli - in the middle part of the cells, so that they give them a fusiform shape (plectridia).
Bacterial spores are recognized by scientists as the most enduring formations of all life forms on planet Earth. Characteristically, at rest, spores have no metabolism. They are resistant to steam, drying, radiation, lack of oxygen, acids. At rest, spores are very durable. They are found in any habitat on Earth. And if favorable conditions arise, then the spores immediately respond to the environment and sprout, resuming active growth.
Examples of pathogenic bacilli
- Bacillus anthracis is the causative agent of anthrax. It is assigned to the second group of pathogenicity.
- Bacillus cereus is a causative agent of foodborne toxic infections in the human body.
- Bordetella pertussis - found in the lungs, causes whooping cough.
- Koch bacillus is the cause of tuberculosis infection and disease.
- Tetanus bacillus is the causative agent of tetanus.
But not all bacilli are harmful. Modern science has learned to use their positive qualities. Some bacilli are used in production as producers of proteinases and amylases. And the toxins produced by them are used as insecticides to protect cultivated plants.