Fermentation tank knowledge

1 Introduction

With the continuous improvement of biochemical technology and biochemical products, the production of antibiotics is also increasing, especially the demand for antibiotics closely related to human health. The production of antibiotics such as penicillin and its semi-synthetic products, erythromycin and its semi-synthetic products has developed rapidly. With the growth of these products, the production process has been continuously improved and the production equipment has been continuously improved. Now the antibiotic fermentation production has realized the whole process of fermentation. The automatic feeding and mixing system adopts frequency conversion speed regulation, which makes the fermentation equipment production easier to control, reduces the infection rate and improves the fermentation level. The conditions are provided. Taking erythromycin production as an example, most of the domestic production plants used 60-120 m3 fermenters before 2000. Most of the new projects now use 200-300 m3 stainless steel fermenters. Therefore, the large-scale fermenter volume puts forward higher requirements on the structure design of the fermenter. The problems worthy of attention in the design of the large-scale fermenter are as follows.

2. Flow and fluid shear

Fermentation can be simply defined as the use of microorganisms to convert one substance into another. The most commonly used microorganisms are bacteria, yeasts, molds, and the like. The food of the microorganisms and the required product are in the form of a slurry, and the viscosity ranges from 2000 to 3000 cp (2~3 pa·s), which is called a glue or a fermentation liquid. The microorganisms in the fermenter produce the desired product under the aerobic condition with the decomposable material as a food. From the viewpoint of mixing, the fermenter involves the functions of gas dispersion, solid suspension, heat transfer and uniform mixing. Each fermentation has its own unique characteristics, so the best structure of the agitator is carefully studied. The most important problem is usually the transfer of oxygen from the air to the fermentation slurry and the transfer of oxygen from the slurry to the microorganisms. Microorganisms can only use oxygen at a certain rate of respiration, which is similar to human breathing, and fermenters must provide a good aerobic environment to meet the microbial respiration rate. The maximum shear stress that each microorganism can withstand is different. Yeasts and bacteria are single-celled plants and are very small. Yeasts have an irregular oval shape with a diameter of about 0.004 to 0.01 mm. Bacteria are even smaller, and most bacteria have a maximum size of less than 0.007 mm and are available in a variety of shapes. Many Bacillus are rod-shaped, yeast is proliferated by germination, and bacteria are proliferated by complex division. The mold is a multicellular filament, which is proliferated by the vegetative growth of hyphae. The hyphal growth structure of the mold inevitably makes the mold sensitive to shearing, and the maximum shear force generated by the agitator should be carefully studied to avoid hindering the growth of these microorganisms.

As the production of antibiotic products increases, the volume of single tanks in fermenters tends to increase, and many new problems have been raised for the designers of fermenters. We should make the structure and agitation of large fermenters more suitable for microbial metabolic processes in fermentation production, increase the oxygen transfer rate in fermentation broth, and improve the level of fermentation production. This is the eternal theme of large-scale fermenter designers.

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Anti-fungal

According to the site of fungal infection,it can be divided into superficial fungal infection and deep fungal infection, superficial fungal infection is caused by ringworm infection of the skin, hair, fingers, toe fingers. The incidence rate is high with less harmful. Deep fungal infection is caused by Candida and cryptococcal invasion of internal organs and deep tissue, the incidence is low with big harmful. Classified based on mechanism action classification can be divided into (1) Antifungal agents for sterol synthesis in fungal cell membranes (2) Antifungal agents for fungal cell wall synthesis (3) Antifungal agents acting on nucleic acid synthesis, The Antifungal drugs easily affect the white blood cells and liver function, if in long-term use,it may caused a transient increase in GPT or leukopenia, withdrawal is normal.