Bacteria are relatively simple microscopic organisms.
Bacteria are the oldest group of organisms currently existing on Earth. The first bacteria appeared probably over 3.5 billion years ago and for almost a billion years were the only living things on our planet.
Spread of bacteria
Bacteria are found everywhere: in a drop of even the purest spring water, in grains of soil, in the air, on rocks, in desert sands, at the bottom of the ocean and even in oil extracted from great depths.
They live in the ice of Antarctica at a temperature of -83 ° С and in hot springs, the temperature of which reaches +85 – 90 ° С.
1 g of soil can contain hundreds of millions of bacteria.
They live on plants, fruits, in various animals and in humans in the intestines, mouth, on the limbs, on the surface of the body.
Living conditions of bacteria
Bacteria are very hardy and adapted to various living conditions. One of them needs oxygen in the air, others do not need it and are able to live in an oxygen-free environment.
Bacteria tolerate drying, extreme cold, heating, without losing their viability. And bacterial spores can withstand even prolonged boiling and very long freezing.
Depending on the shape of the cell, bacteria are distinguished:
single spherical – cocci,
cocci folded in a chain – streptococci,
bunches of cocci (like a bunch of grapes) – staphylococci,
two rounded bacteria enclosed in one mucous capsule – diplococci,
rod-shaped – bacilli,
spiral – spirilla,
in the form of a comma – vibrios, etc.
Bacteria often form clusters in the form of long, curved chains, groups, and films. Some bacteria have one or more flagella. Among bacteria there are mobile and immobile forms. The mobile ones move due to wave-like contractions or with the help of flagella.
Most bacteria are colorless. Only a few are colored purple or green.