The bacterium is the smallest unicellular organism that exists on Earth, it belongs to the monera kingdom, it is characterized by having a prokaryotic cell, in which its genetic material is usually found grouped in a nuclear region that lacks its own envelope or membrane; that is, it does not have a nucleus or cellular organelles (mitochondria, chloroplasts, etc.). By their shape, bacteria can be classified into: bacilli (elongated or rod-shaped), vibrios (curved), spirillae (wavy or spiral-shaped) and cocci (rounded). The latter can occur singly, in pairs (diplococci), in aligned groups (streptococci), in irregular masses (staphylococci) or in cubic masses (sarcins).
The bacteria also has as its nutrition, ability to use different forms of energy and chemical structure of their cell wall or some variety differences. Some are heterotrophic, they do not require a power source to survive; and others are autotrophs (photosynthesizers or chemosynthesizers) capable of obtaining energy from simple substances.
The heterotrophic bacteria along with fungi, enrich the soil and promote plant growth, thus decompose organic matter, thus playing a key role in ecosystems.
A large number of bacteria are those that produce some most common and dangerous diseases in living organisms such as cholera, syphilis, pneumonia, tetanus, typhus, diphtheria, etc. However, it should be noted that some bacteria are useful, help to break down digested food and others are capable of producing antibiotics and are used in scientific research specifically in biotechnology and genetic engineering.
On the other hand, the bacteria have a wide industrial use in the manufacture of cheese, yogurt and dairy derivatives, as a result of the lactic fermentation process; wine, beer and other alcoholic beverages, obtained in alcoholic fermentation; vinegar or acetic acid, obtained in acetic fermentation, and also in the production of citric acid, acetone, among others.
