Contamination of fermentation tanks and pipelines may lead to fermentation failure. Therefore, we should focus on prevention and eliminate various hidden dangers that may cause bacterial contamination.
Ensure the sealing of fermenter
Before use, check whether the fermenter stirring system rotates abnormally, whether the mechanical seal is tight, whether the screws in the tank are loose, whether the pipes in the tank are blocked, and whether the tank connection valve is tight.
PVDF filter membrane is used in the air inlet pipeline of fermenter
The traditional air purification system uses activated carbon, cotton and ultra-fine fiberglass paper as the filter core, which has poor filtration effect and complex operation. At present, the membrane filtration technology has been relatively mature, such as the folded microporous membrane filter core made of polyvinylidene fluoride (PVDF) not only has high filtration accuracy, but also has a large flow rate.
Pay attention to removing water and oil from the compressed air before entering the filter, and sterilizing the filter according to specifications to ensure that the air is sterile. In addition, because the PVDF membrane is not sensitive to moisture in compressed air and the membrane itself is highly hydrophobic, it can solve the problem that cotton filters cannot be used when the air humidity is too high.
Sterilization process monitoring
The thorough sterilization of the fermentation medium uses high-temperature supersaturated steam to kill various bacteria and fungi. During the sterilization process, there are strict requirements for preheating time, steam valve opening, sterilization temperature, sterilization pressure and foam control. Problems in any of these links can easily lead to bacterial contamination.
Generally, the sterilization temperature is 121°C and the sterilization pressure is 0.1Mpa. Ensuring the accuracy of sterilization temperature and pressure relies on various temperature probes, pressure sensors and other monitoring systems. Therefore, it is very important to test probes and sensors regularly. In addition, as the volume of the fermenter increases, the tank temperature corresponding to the same tank pressure decreases. Therefore, when the correlation between temperature and pressure is found to change, the temperature should prevail.
Fermenter valve adopts soft seal
Valves generally use soft gaskets, which use the larger elastic-plastic deformation of the gasket to form a wider annular sealing contact zone to fill up the unevenness on the sealing surface and eliminate gaps to form a seal. The sealing performance of the valve can be ensured by regularly replacing the sealing gasket.
Prevention of bacterial contamination in fermenter
1. Sterilize before fermentation
2. The seed liquid cannot contaminate other bacteria
3. The air filter must ensure quality
4. Be careful not to have too much foam during the fermentation process
5. Ensure the sterility of the air inlet system
6. Special attention should be paid to the tightness of the fermenter, especially some dead corners.
7. If transplantation is required, the sterility and dead ends of the transplantation pipeline must also be ensured.
8. If feeding is required during the fermentation process, the feeding system must be sterile.
