Bacteria

What are Bacteria?

Bacteria are microorganisms, very small living beings with dimensions in the order of one thousandth of a millimeter.

Even if we cannot see them with the naked eye, bacteria are everywhere, in our body and in the whole environment that surrounds us; some of them even live in the most inhospitable environments, such as the ocean floor or glaciers. In addition to being omnipresent, bacteria are also among the most widespread living forms on earth, so much so that up to 10,000 billion of them can be found in a single spoonful of soil.

Often, bacteria are associated with dirt or certain diseases, but in reality many of them are particularly useful to humans; let's think, for example, of the bacteria that allow the production of yogurt or those that make up the intestinal symbiont flora.

In-depth articles

Bacteria: General Characteristics

Type of body

Prokaryote, usually unicellular.

Dimensions

They are in the order of the micrometer, which is the millionth part of the meter; generally they oscillate between 0.2 and 10 µm;

Form

The shape of the bacteria varies according to the type of bacterium considered:

coconut: spherical
bacillus: rod-shaped
vibrions: comma (have a curvature)
spirilli: spiral (large pitch cylindrical helix shape)
spirochete: corkscrew (very short step sinusoids)

DIPLOCOCCHI: bacteria associated two by two

STREPTOCOCCHI: chain

TETRADES: groups of four cells
SARCINE: eight cube-shaped chariots STAFILOCOCCHI: cluster

Examples of Bacteria with Different Shapes

Reproduction

Generally asexual, by simple division (or binary division); each bacterium (mother cell) splits into two units, giving rise to two daughter cells identical to the original. During this process bacterial aggregates can form, from which colonies consisting of cells different in number and position originate:

Bacterial reproduction occurs in two distinct phases:

increase in the size of the bacterium, which synthesizes and develops the various cellular structures;
division of the parent cell to give rise to two daughter cells.

The growth of the bacterial population follows a characteristic trend, which makes it divisible into four phases:

LATENCY: bacteria synthesize the substances necessary to prepare for division and do not increase in number; its duration varies from species to species and in relation to environmental conditions.
OF EXPONENTIAL GROWTH: every 10 - 60 minutes the number of bacteria doubles (logarithmic development).
STATIONARY PHASE: nutrients are scarce and the number of new cells equals the number of dead bacteria.
DEATH: the drastic drop in nutrients leads to the death of a number of bacteria higher than that of cells still able to reproduce.