They reproduce quickly in your body. Many give off chemicals called toxins, which can damage tissue and make you sick. Examples of bacteria that cause infections include Streptococcus, Staphylococcus, and E. coli.

Human Uses of Bacteria

• Fermentation processes, such as brewing, baking, and cheese and butter manufacturing.
• Chemical manufacturing, such as the production of ethanol, acetone, organic acids, enzymes, and perfumes.
• Pharmaceuticals, such as the manufacture of antibiotics, vaccines, and steroids.

Bacteria are microscopic, single-celled organisms that exist in their millions, in every environment, both inside and outside other organisms. Some bacteria are harmful, but most serve a useful purpose. They support many forms of life, both plant and animal, and they are used in industrial and medicinal processes.

They can be divided into six major types: bacteria, archaea, fungi, protozoa, algae, and viruses.

Bacteria are the plural of bacterium, which are microscopic one-celled organisms. They are found everywhere and can be harmful, as in bacterial infections, or they can be beneficial, as in fermentation or decomposition. The three main bacteria shapes are coccus, bacillus and spiral.

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Bacteria (singular: bacterium) are a major group of living organisms. Most are microscopic and unicellular, with a relatively simple cell structure lacking a cell nucleus, and organelles such as mitochondria and chloroplasts. Bacteria are the most abundant of all organisms.

In some ways, viruses are both living and non-living. They have genetic information that evolves through natural selection. They assemble themselves. You can’t say either of those things about rocks, clouds, or stars.

For young students things are ‘living’ if they move or grow; for example, the sun, wind, clouds and lightning are considered living because they change and move.

Some examples of important nonliving things in an ecosystem are sunlight, temperature, water, air, wind, rocks, and soil. Living things grow, change, produce waste, reproduce, and die. Some examples of living things are organisms such as plants, animals, fungi, and bacteria.

All living organisms share several key characteristics or functions: order, sensitivity or response to the environment, reproduction, growth and development, regulation, homeostasis, and energy processing. When viewed together, these characteristics serve to define life.