What are the culture conditions that need to be controlled when experimentally culturing microorgani

carbon sources; nitrogen source; Inorganic salt; growth factors; Water; ph

1.Choose the right nutrients: Due to the complex types of microbial nutrition, different microorganisms have different requirements for nutrients, so it is necessary to first prepare a highly targeted medium according to the nutritional needs of different microorganisms.

2.Appropriate nutrient concentration and ratio: microorganisms can grow well when the nutrient concentration in the medium is appropriate, and when the nutrient concentration is too low, it cannot meet the normal growth needs of microorganisms, and when the concentration is too high, it may inhibit the growth of microorganisms.

3.Control pH conditions: The pH of the medium must be controlled within a certain range to meet the growth and reproduction of different types of microorganisms or the production of metabolites.

4.Controlling redox potential: Different types of microorganisms have different requirements for redox potential, and it is necessary to choose the appropriate one.

5.Selection of raw materials: In the preparation of the medium, we should try to use cheap and easily available raw materials as the components of the medium, especially in the fermentation industry, the amount of medium is very large, and the use of low-cost raw materials reflects its economic value.

6. Sterilization treatment: In order to obtain pure microbial culture, it is necessary to avoid contamination by miscellaneous bacteria, so the equipment and workplace used are disinfected and sterilized. For the culture medium, it is necessary to carry out strict sterilization.

1. Nutrition: six major nutrients - nitrogen source, carbon source, inorganic salts, energy substances, growth factors, and water.

2. Growth conditions: temperature, pH, oxygen capacity, carbon dioxide concentration, etc. (generally the first two are the main), in addition to the rotation speed, and some organisms also need to consider the influence of air pressure.

Conditions and reasons for cultivating microbial culture medium:

1. Carbon source. That is, to provide the energy required for the growth and reproduction of microbial strains, the carbon components necessary for the synthesis of bacteria, and the carbon components necessary for the synthesis of the target product. The common ** mainly includes sugars, oils, organic acids, n-alkanes, etc.

Sugars commonly used in industry mainly include: glucose, molasses (crystalline mother liquor in sugar production), starch, etc.

2. Nitrogen source. The nitrogen source is mainly used to constitute cellular substances (amino acids, proteins, nucleic acids, etc.) and nitrogen-containing metabolites. Commonly used nitrogen sources can be divided into two main categories:

Organic and inorganic nitrogen sources. Organic nitrogen sources and inorganic nitrogen sources should be mixed, and nitrogen sources that are easy to use and easily assimilate should be used in the early stage of fermentation, that is, inorganic nitrogen sources; In the middle stage, the metabolic enzyme system of the cell has been formed, and the protein is used.

3. Inorganic nitrogen source.

Inorganic nitrogen sources mainly include ammonium salts, nitrates, and ammonia. Microorganisms absorb them quickly, so they are also called rapid nitrogen sources. However, the rapid utilization of inorganic nitrogen sources often causes changes in pH.

After the inorganic nitrogen source is used by the bacteria as a nitrogen source, acidic or alkaline substances are left in the culture medium, and the inorganic nitrogen source that can form acidic substances after microbial physiological action (metabolism) is called physiological acidic substances, such as ammonium sulfate; If the bacteria can produce alkaline substances after metabolism, this inorganic nitrogen source is called physiological alkaline substances, such as sodium nitrate. The correct use of physiological acids and alkalis has a positive effect on stabilizing and regulating the pH of the fermentation process.

1) Objectives of the experiment (1) To understand the distribution of microorganisms in the air. (2) Compare the number and type of microorganisms present in the air of ordinary laboratories and clean rooms. and (3) validating the importance of aseptic manipulation in microbiology experiments.

2) Experimental Principles There are a wide variety and large number of microorganisms in the environment around us. In the air is no exception. Although the air is not a good environment for microorganisms to inhabit.

However, due to air currents, the flow of dust and water foam, and the activities of people and animals, a considerable number of microorganisms still exist. When individual micro-organisms in the air fall on the surface of a solid medium suitable for their growth and reproduction, after being cultured at the right temperature for a period of time, each scattered cell or spore will form a visible cell population, that is, a colony. By looking at colonies of different sizes and shapes, we can roughly identify the types of microorganisms present in the air.

In this experiment, the microorganisms present in the air of the general laboratory and the sterilized clean room were detected, so as to judge the disinfection effect of the clean room and understand the common microbial groups in the air.

3) Experimental equipment (1) Medium: 1) Beef paste peptone medium. 2) Potato sucrose medium. (2) Equipment: several sets of sterile plates, alcohol lamps, incubators, etc.

4. Experimental method (1) Inverted plate: Configure the above medium according to the usual method, divide it into triangular bottles, and autoclave it for later use. Before use, melt the medium, cool it to about 50, and pour several plates for later use.

2) Detection: Turn on the ultraviolet lamp in the sterile room first, and turn it off after irradiation for 15min. Open the lid of the condensed and merged sterile plate and expose it to IH in the sterile room space and the normal laboratory space where no one walks around, respectively, and close the lid of the dish.

Plates of each medium are required to have 3 replicates per space. (3) Culture: The bacterial medium plate and the fungal medium plate were respectively inverted in the incubator of 37 and 28, and continuous observation began after 1-2 days, paying attention to the order of different types of colonies and the changes in the size, shape, color, dryness and wetness of the colonies.

1) Must contain raw materials used as components of synthetic cells, such as carbon sources, nitrogen sources, inorganic salts, and growth factors;

2) Meet the basic conditions of general biochemical reactions;

3) Certain pH and other conditions.

The medium for cultivating microorganisms should have the following conditions: nutrients, light, water, suitable temperature and a certain living space.

Carbon source: Provides microbial nutrient carbon (carbon frame).

Nitrogen source: provides the nitrogen required for the growth and reproduction of microorganisms.

Energy: Inorganic salts.

Macroelements: intracellular components, osmotic pressure.

Composition, pH stabilization, enzyme activator MG2+; Trace element.

Activators of enzymes, special molecules or structures.

Growth factor: an organic substance that is essential for the normal metabolism of microorganisms and cannot be synthesized from simple carbon sources and nitrogen sources, generally requires very little amount, and the function of microbial body energy is mainly coenzyme or coenzyme.

Water: essential in the course of life.