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production of microbial enzymes(2)

Data: 2020-10-03


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production of microbial enzymes(2)

     Fermentation production

The production of microbial enzymes currently mainly adopts two methods, liquid submerged fermentation and solid fermentation. 

Compared with other culture methods, liquid submerged fermentation has the following advantages: 

1) The liquid suspension state is the most suitable growth environment for many microorganisms; 

2) In the liquid environment, the bacteria, substrates, and products (including heat) are easy to diffuse and make Fermentation is carried out under homogeneous or pseudo-homogeneous conditions, which is easy to detect and control, and is easy to expand the production scale; 

3) the liquid is convenient to transport and easy to mechanize operation; 

4) the product is easy to extract and refine. 

Compared with liquid fermentation, solid fermentation has the following disadvantages: 

1) The production process is mainly limited to bacteria resistant to low water activity; 

2) The growth rate of microorganisms is slower and the products are limited; 

3) The metabolic heat generated is more difficult in large-scale operation. Dispersed, it is difficult to accurately determine the solid-state fermentation parameters during the production process, and it is difficult to realize the mechanization of the operation and the automation of the control; 

4) The design of the biochemical reactor is not perfect, and the traditional fermentation method is easy to contaminate the bacteria. 

However, solid fermentation also has many advantages that liquid fermentation does not possess. The main manifestations are: 

1) The medium is simple and mostly inexpensive natural substrate; 

2) The low water content of the substrate can greatly reduce the volume of the biochemical reactor. Waste water treatment, less environmental pollution, often does not require strict aseptic operations, and convenient post-treatment processing; 

3) It is not necessarily continuous ventilation, and can generally be completed by intermittent ventilation or gas diffusion; 

4) Product yield can be higher; 

5) The equipment is simple, the investment is small, and the energy consumption is low. 

Due to the low added value of the feed industry, the feed enzyme does not need to be refined, so solid-state fermentation is more appropriate. 

The production of domestic compound enzyme preparations generally adopts solid-state fermentation, and liquid fermentation is mainly used for the production of phytase or the production of single enzyme preparations for compound enzyme preparations.

The fermentation production of microbial enzymes is completed by the interaction of microbial biochemical activities and environmental conditions. In fermentation production, only environmental conditions can be directly adjusted and controlled. 

In addition to the composition of the culture medium and its concentration, environmental variables such as inoculum, temperature, pH, and dissolved oxygen can also affect microbial metabolism. 

In solid fermentation, the air humidity and material moisture content in the fermentation space also seriously affect the metabolism of bacteria Activity and enzyme production. 

Different strains require different technological conditions for the production of enzyme preparations. The optimal technological parameters must be determined through experiments. 

Only when an optimal environment is provided for the culture, can the metabolic activities of the bacteria be expressed fully and the enzyme production Only high.

    The extraction of enzymes

In the fermentation substrate, enzymes coexist with a large number of other substances, and the content of enzymes is much less than other substances, so industrial enzymes need to separate enzymes from a large number of other substances. 

But feed enzymes do not need pure enzymes, and the substrates used in fermentation and the amino acids, vitamins, nucleotides, growth-promoting factors and other components produced during the growth process of the bacteria are beneficial to the growth of livestock and poultry, so feed enzymes do not need Refining, as long as the fermentation substrate is concentrated (for liquid fermentation) and dried to obtain a crude enzyme product.

    Preservation of enzymes

Enzymes are biologically active substances. Some physical and chemical factors such as acids, alkalis, organic solvents, heavy metals, surfactants, high temperature, ultraviolet rays, etc., can easily cause structural changes and cause enzyme inactivation. 

Care should be taken to avoid these unfavorable factors during preservation. For the maintenance of enzymes, to keep the enzymes from deactivation for a long time, the key is to control the two conditions of moisture and temperature. 

Generally, the enzyme is easy to inactivate when the water content is high, and the water content exceeds 10%, and it is easy to inactivate at room temperature or low temperature; when the water content drops to 5%, it is more stable at room temperature or low temperature. 

The higher the temperature, the easier to inactivate. Therefore, it is best to store enzyme products at low temperature, especially when the water content of enzyme products is high, it is better to store them at low temperature. 

Sunlight sometimes causes the inactivation of certain enzymes, so enzymes should be protected from direct sunlight. Some heavy metal ions (such as copper, iron, lead, mercury, silver, etc.) can inhibit the activity of enzymes, and even inactivate the enzymes, so avoid contact with these substances as much as possible. 

The substrate and certain substances of the enzyme have the function of preserving the enzyme, so the enzyme stabilizer or coating treatment should be added according to the different characteristics of the enzyme during storage, so that the enzyme will not be inactivated for long-term storage.