Animal Breeding Examples
Microorganisms (bacteria, microscopic fungi, protozoa, etc.) play an extremely important role in the biosphere and human economic activity (see chap. 5, 6). Out of more than 100 thousand species of microorganisms known in nature, several hundreds are used by humans, and this number is growing. A qualitative leap in their use has occurred in recent decades, when many genetic mechanisms for regulating biochemical processes in the cells of microorganisms were established.
Many of them produce dozens of types of organic substances – amino acids, proteins, antibiotics, vitamins, lipids, nucleic acids, enzymes, pigments, sugars, etc., widely used in various fields of industry and medicine. Such food industries as bakery, alcohol, dairy products, winemaking and many others are based on the activity of microorganisms.
The microbiological industry imposes stringent requirements on the producers of various compounds, which are important for production technology, such as a high growth rate, the use of cheap substrates for life, and resistance to infection by extraneous microorganisms. The scientific basis of this industry is the ability to create microorganisms with new, predefined genetic properties and the ability to use them on an industrial scale.
The selection of microorganisms (unlike the selection of plants and animals) has a number of features: 1) the breeder has an unlimited amount of material for work: billions of cells can be grown in Petri dishes or tubes on nutrient media in 2 days; 2) more efficient use of the mutation process, since the genome of microorganisms is haploid, which makes it possible to identify any mutations in the first generation, 3) the simplicity of the genetic organization of bacteria: a significantly smaller number of genes, their genetic regulation simpler, gene interactions are simple or absent.
These features leave their mark on the choice of methods for the selection of microorganisms, which in many respects differ significantly from the methods of breeding plants and animals. For example, in the selection of microorganisms, their natural abilities to synthesize any compounds useful for humans (amino acids, vitamins, enzymes, etc.) are usually taken into account. In the case of using genetic engineering methods, bacteria and other microorganisms can be forced to produce those compounds whose synthesis in natural conditions they have never been inherent in (for example, human and animal hormones, biologically active compounds).