Analysis of the causes of changes in the genetic characteristics of strains

From the microscopic point of view of the genetic mechanism of the species, there are three main reasons for the change of the genetic characteristics of the species(1) the phenomenon of heteronuclear seis causes the microbial population to mutatesome mycelium will grow with the adjacent mycelium cells, the formation of isonucleolias (i.ei.e., heterocore), that is, in a mycelium contains several different genetic characteristics of the nucleus, living together in the celiacHeteronuclears can be formed by the match of different herstites, or they can be produced by mutations in individual nucleosinMononucleosomes produced by mononucleosomes have different genetic characteristics and different growth and reproduction rates, the result is accompanied by the generation of bacterial culture, the genetic characteristics of the species changeMany newly isolated silk bacteria from the medium are heterocores during the process of species selectionIn antibiotic production, the natural separation of mononucleosomes from the heterocores that produce mononucleic spores can be achieved, and the monobacteria of the same nucleus can be obtained, many of which exhibit stable production capacity(2) spontaneous mutations lead to changes in the genetic characteristics of the bacteriadue to accidental errors in DNA in the replication process, and the stimulation of microorganisms by certain substances and certain microorganisms themselves in the environment, the strains undergo spontaneous mutations at a very low frequencyhybrids formed by variants or hybrid recombinations produced by(3) mutations are often unstable and prone to re-mutations or isolators, resulting in the formation of individuals with different genotypes (also called genotypes) in the strain groupmore thangenetic factors that cause mutations in the strains, these factors will be manifested through the environmentIn the process of using the production of strains, it is necessary to pass on under artificial culture conditions, although the original oblique bacteria are developed by single colonies, but many of the spores on the colonies already have different genetic bases, so the characteristics of the strains are actually characteristics of the spore populationmore pure groups, less variation after transmission; In the process of serological culture, the above several reasons that lead to the change of the genetic characteristics of the bacteria can play a role, the result of which leads to the increase of mutant strains in the populationThe generation of culture also has a certain choice the high-yielding strains associated with the excellent characteristics of the species and the large number of products produced by the genes of the species often exhibit the characteristics of weak living power and slow growth and reproduction These characteristics make the generation culture essentially have the function of enriching low-yielding strains Therefore, too many transmissions of bacteria will lead to the decline of the bacteria in addition, the improper preservation conditions of the bacteria will also cause the bacteria to mutate Some of the methods used in the preservation process of the bacteria, such as freeze-drying, can cause damage to the structure and DNA of the bacterial cells, and when these damages are repaired, the bacteria may mutate