Separation screening of bacteria produced by industrial microorganisms (I)

strain separation is the process of separating a sample mixed with various
microbials
through the separation technique and taking a rapid, accurate and effective method to separate, screen and obtain the desired microorganisms according to actual requirements and the characteristics of the strain. Although the strain separation and screening are two links, they cannot be separated, because some of the measures in the separation itself have a screening effect. The screening of industrial microbial bacteria generally consists of two parts: one is to isolate the required strains from nature, and the other is to further purify the isolated wild strains and identify metabolites.
In the experimental work, in order to achieve the effect of screening with less effort, the following methods can be collected and screened in general:
(1) to the species preservation agency to obtain the relevant strains, from which to screen the required strains.
(2) samples collected by nature, such as soil, water, flora and fauna, etc., are separated and screened.
(3) to isolate the intended strain from some fermented products, such as
protease
from soy sauce to produce bacteria, and from wineto isolate amylase or glycase to produce bacteria. After a long period of natural selection, this type of fermented products has a long history, from these traditional products easy to screen to the ideal strain.
and screening of these strains can be divided into sampling, collection, separation and product identification.
natural bacteria samples are extremely rich, soil, water, air, dead leaves, plant disease strains, rotten fruit, etc. are containing many microorganisms, the number of species is very considerable. Overall, however, soil samples contain the most bacteria.
, sampling from soil
soil is the most concentrated place for microorganisms because of the nutrients, air and moisture they need. From the soil can be isolated to almost any required strains, air, water microorganisms are also derived from the soil, so soil samples are often the preferred target for collection. In general, the soil contains the largest number of bacteria, and the amount of bacteria per g of soil generally has the following decreasing law: bacteria (108) > line bacteria (107) > mold (1 106) > yeast (105) > algae (104)> progenitic animals (103), wherein the line bacteria and mold refers to the number of spores. However, the distribution of various microorganisms in the soil also changes greatly with geographical conditions, nutrients, moisture, soil quality and season. Therefore, before separating the strain, according to the purpose of separation screening, to the corresponding environment and region to collect samples.
(i) According to the characteristics of the soil
1. Soil
organic
quality content and breathability
General cultivation soil, vegetable garden soil and suburban soil organic matter content is rich, adequate nutrition, and soil granulation structure, gas-rich water performance is good, therefore, the growth of microorganisms, a large number, especially suitable for bacteria, line bacteria growth. Forest soil on hillsides, thick vegetation, dead branches and leaves, rich organic matter, and dark and humid, suitable for mold,
yeam
bacteria growth and reproduction, the number of microorganisms correspondingly less.
From the vertical profile of the soil layer, 1 to 5 cm of topsoil due to sunlight, evaporation, less moisture, and ultraviolet sterilization, so the number of microorganisms than 5 to 25 cm soil layer less; Therefore, the best soil layer for soil mining samples is 5 to 25 cm. In general, there are hundreds of thousands to billions of bacteria per ter tern of soil, and all types of bacteria and line bacteria can be isolated almost. Such as good gas spores, fake monocytobacteria, Syricobacteria, E. coli, some anti-gas bacteria. But in general yeast distribution soil layer is the shallowest, about 5 to 10 cm, mold and aerobic spores are also distributed in shallow soil layer.
2. Soil acidity and vegetation conditions
soil acidity and alkalinity can affect the distribution of microbial species. Alkaline soil (pH7.0 to 7.5) environment, suitable for bacteria, line bacteria growth. Conversely, mold and yeast grow vigorously in acidic soil (below pH7.0). Vegetation also has an effect on microbial distribution due to differences in the secretions of plant roots. Such as tomato land or rotting tomato accumulation there are more vitamin C production bacteria. When grapes or other fruit trees mature, the amount of yeast in the soil near their roots increases. Under the vegetation of soybean plants, the number of root tumor bacteria is superior to that of other vegetation.
3. Geographical conditions
southern soils have more microbials than northern soils, especially in tropical and subtropical areas. Many industrial microbial strains, such as
antibiotics
produce bacteria, especially mold and yeast, mostly filtered out of southern soil. The reason is that the southern temperature is high, the warm season is long, the rain is more, the relative humidity is high, the plant species is many, the vegetation coverage is large, the soil organic matter is rich, resulting in the unique microbial growth environment.
4. Seasonal conditions
there are significant changes in the number of microorganisms in different seasons, low winter temperatures,
dry
, slow growth of microorganisms, the lowest number. In spring, as the temperature rises, the number of microorganisms grows vigorously and increases gradually. But in the south, spring tends to have a lot of rain, high soil moisture content, poor breathing, even if there is the temperature and humidity required by microorganisms, it is not conducive to its growth and reproduction. Then after summer to autumn, about 7 to 10 months in high temperatures and rich vegetation, the number of microorganisms in the soil than ever before, therefore, autumn soil samples are the most ideal.
(ii) sampling method
with sampling shovel, the surface of about 5cm of floating soil removed, take 5 to 25 soil samples 10 to 25, put in a pre-prepared plastic bag. The soil in the north is dry and can be sampled at 10 to 30 places. Number the plastic bag and record the location, soil texture, vegetation name, time, and other environmental conditions. General samples should be separated immediately after they are recovered to avoid microbial death. But sometimes more samples, or to the field sampling, long distance, difficult to achieve timely separation, you can use selective
transcing
base to do a good job of
tive tube
slope, take away with you. To a place will take the soil sample mixed well, take 3 to 4 sprinkled on the test tube slope, so as to avoid the strain can not be separated in time and death.