Bacteria

Bacteria are ubiquitous prokaryotic  organisms with a size of 0,3–10 μm.

General information
Bacteria belonged to the evolving chain of life on Earth. They originated about 3 billion years ago and affected both the development of the environment and the development of other species, as infections are important factors in selection. More than 2000 species of bacteria have been described. They do not have a nuclear membrane or nucleolus. Transcription and translation take place almost simultaneously in the cytoplasm. They have an irreplaceable role in ecosystems:


 * degrade organic matter and recycle nutrients (saprophytes)
 * some are able to capture atmospheric nitrogen
 * they are extremely adaptable – they show a huge diversity of metabolism and the ability to use different energy sources

The shape of bacteria



 * round (cocci)
 * rod-shaped (vibria, spirils, spirochetes)

Types of bacteria and their way of life
Bacteria are equipped with numerous chemoreceptors  → they respond by movement (positively / negatively) to:


 * oxygen concentration
 * lighting
 * chemicals (eg. glucose)
 * presence of their own metabolic products

Bacteria are highly adaptable.


 * Heterotrophic bacteria:

They act as decomposers in the process of recycling substances in nature. It feeds on decomposition products and dead organic matter. As parasites they can cause infectious diseases in plants and animals.


 * Autotrophic bacteria:

They are able to obtain energy through photosynthesis or oxidation of inorganic substances. The enzymatic equipment of bacteria is diverse - it corresponds to the environment to which they have adapted with their development.


 * Prototrophic bacteria:

They are able to live on minimal soil and synthesize all the substances needed for life.


 * Auxotrophic bacteria:

Biochemical loss mutations cause bacteria to be able to grow only in an environment that contains a substance that they are unable to synthesize.

According to the need of oxygen we divide bacteria into:


 * aerobic bacteria: they need oxygen for their metabolism
 * anaerobic bacteria: unable to survive in the presence of oxygen. Therefore, they endanger patients with tissue circulatory disorders, eg. after injuries.
 * facultatively anaerobic: bacteria capable of living in both aerobic and anaerobic environments
 * capnophilic, microaerophilic bacteria: they grow best in environments with increased CO2 content

The importance of bacteria in medicine
E. coli is a rod-shaped bacterium that moves with the help of flagella. It is part of the intestinal microflora of all warm-blooded animals. It has its place in the large intestine and the lower part of the small intestine. As part of the intestinal microflora, it is beneficial to humans. It produces a number of substances that prevent the spread of pathogenic bacteria. In addition, it is involved in the production of certain vitamins. Humans have been colonized by this bacterium since birth.

This bacterium plays an important role in insulin production. (Insulin from pigs for slaughter used to be used for treatment. Due to allergic reactions, insulin production was switched to using genetically modified E. coli.) In addition, it is used in the preparation of human growth hormone, Lyme disease vaccine, amino acid production, parathyroid hormone and calcitonin. Probiotic E. coli strains can be used to treat infections caused by adherent invasive E. coli and in the treatment of Crohn's disease.

In genome engineering bacteria can help us due to the fact that they contain a small amount of DNA – plasmids. We isolate plasmids from the bacteria, attach parts of the DNA from the chromosomes of animals and plants to them, and use them to produce proteins that the bacteria themselves are unable to produce. In this way, for example, insulin and other important substances can be synthesized with the help of bacteria. Abroad, they produce insulin and growth hormone in this way.

Related articles

 * Bacterial structure
 * Bacterial reproduction
 * Conjugation, Transformation and Transduction.
 * Prokaryotes
 * Regulation of gene expression in prokaryotes