Growth and reproduction of microorganisms

, the growth and reproductionof microorganismsmicrobes in the appropriate environmental conditions, the continuous absorption of nutrients, and in accordance with their own metabolic mode of metabolic activities, if the assimilation effect is greater than alienation, then the amount of cytoplasmic increase, volume can be increased, so the performance of growthSimply put, growth is an increase in the amount of cellular components and structures of an organismsingle-celled microorganisms, such as bacteria, whose growth is often accompanied by an increase in the number of cellsWhen cells grow to a certain extent, two basically similar subcells are formed in a two-way division, and the subcells repeat the processIn single-celled microorganisms, an increase in the number of individuals caused by cell division is called reproductionIn general, growth and reproduction are always alternating when environmental conditions are appropriateFrom growth to reproduction is a process of change from quantity to mass, which is development(Pictured is the split breeding of Ecoli, but it took me a lot of energy.) ^-^)microorganisms are in certain physical and chemical conditions, growth and development is normal, the rate of reproduction is also high, if one or some environmental conditions change, and beyond the range of biological adaptation, will have a inhibition and even killing effect on the body, bacteria pure culture of the group growth lawmost bacteria reproduction speed is very fast, Ecoli in the right conditions, every 20 minutes or so can split once, if always maintain such a rate of reproduction, a bacteria in 48 hours, its sub-group will reach an unimaginable numberHowever, this is not the caseinoculated a small amount of single-celled pure culture into a constant volume of fresh liquid medium, cultured under appropriate conditions, timed sampling to determine its bacterial content, you can see the following phenomenon: a short time at first, the number of bacteria does not increase, with the number of bacteria increased rapidly, both and the number of bacteria stabilized, and finally gradually decreased If you plot the log coordinates of the number of bacteria or the growth velocity of bacteria in horizontal coordinates, a curve, called a reproductive curve, or growth curve, can be obtained The growth curve represents the dynamic change of the whole process of bacteria growing and multiplying in a new and suitable environment until aging dies According to the different growth and reproduction rate of bacteria, the growth curve can be divided into four stages: delay period, interstitial period, stabilization period and decay period (1) delay period: a small amount of bacteria inoculated into a fresh medium, generally do not reproduce immediately, the growth rate is near zero So for some time at the beginning, the number of bacteria remained almost constant, even slightly reduced This period is known as the delay period, also known as the delay period, the adjustment period, or the retention adjustment period Bacterial cells in the delayed period are characterized by slow division and metabolic activity The length of the delay period was related to the strains, age, inoculation and medium composition (2) dates: the divination period is also known as the exponential period This stage is characterized by the increase in the number of bacteria in geometric series, time stability, the increase in the number of bacteria and the increase of the total amount of protoplasm, and the increase of the turbidity of the bacteria liquid are positively correlated (3) stability period: also known as constant regular or maximum long-term In the stable period of microorganisms, the number of newly proliferated cells and the number of deaths of old cells is almost equal, the whole culture is in a dynamic balance, at which time the growth rate gradually tends to zero The concentration of storage in the cells during the stabilization period begins, such as liver sugar, hetero-dyed particles, fat particles, etc., and most spores also form spores at this stage If in order to obtain a large number of bacteria, it should be harvested at this stage, because the total number of cells is the highest at this time, this period is also an important stage of the fermentation process accumulation of metabolites, the formation of a large number of antibiotics of certain line bacteria is also in this period (4) decay period: if the stabilization period continues to be cultured, the bacterial mortality rate gradually increases, so that the number of deaths greatly exceeds the number of new students, the number of live bacteria in the group fell sharply, there was a "negative growth", this stage is called the decay period "text-align: center;"img src""alt""microbial growth and reproduction" title""microbial growth and reproduction"