Fermenter is a very important and key industrial equipment in the field of biotechnology and chemical engineering, which is widely used in pharmaceutical, dairy products, beverages, health food, bioengineering, fine chemicals and other industries, because it can carry out microbial culture and fermentation, and make microorganisms grow efficiently and secrete target products. Fermenter is usually made of stainless steel and generally adopts a cylinder structure with a volume ranging from one cubic meter to hundreds of cubic meters, which is suitable for production needs of different scales.
Fermenter production process includes material input, fermentation process, liquid/solid state separation , purification stages,etc. In the fermentation process, the microbial body is transformed from a low-density, suspended state to a high-density, attached state through appropriate environmental and nutritional conditions, so as to carry out synthetic convergence and produce the required high-purity biological products.
The process parameters of the fermenter include temperature, pressure, pH value, nutrient composition, oxygen content, etc., which can affect the growth of microorganisms, and then affect the quality and yield of biological products produced. By monitoring and adjusting these process parameters, the quality and outcome of the biological reaction can be controlled.
In short, fermenters are widely used in the fields of biotechnology and chemical engineering, they are blessed with high production efficiency and economic value, and they have made important contributions to the development of human production, medical , health care and so on.
Microbe refers to very small organisms, which are a very diverse and numerous organism in nature. They are widely distributed in the natural environment, including soil, water, ocean, air and other media, and play an important role in maintaining ecosystem stability and energy cycle.
Microbes from different sources and different environments have a very high diversity, and their types and numbers are very large. At the same time, different kinds of microorganisms also show obvious biological exclusivity with other microorganisms, that is, when the certain strain is mass-production in the certain environment, the growth and reproduction of other strains will be inhibited to the certain extent.
Therefore, when conducting microbial culture and fermentation in the fermenter, it is necessary to ensure that the target microorganisms are not interfered with and affected by other microorganisms, so it is necessary to conduct thorough sterilization and aseptic operation on the fermenter, so that there are no other impurities or microorganisms in the fermenter, only the required target microorganisms exist, so as to ensure the quality and efficiency of the fermentation process.
Steam sterilization is a common fermenter sterilization method, which uses high temperature and high pressure steam to sterilize the inner wall and internal materials of the fermenter. This process can effectively kill various bacteria, fungi, viruses and other microorganisms.
3.1 Advantages of steam sterilization
Sterilization effect is good ,sterilization speed is fast speed and its operation is simple. In theory, it can effectively kill various bacteria, viruses and fungi, including spores that are difficult to inactivate. At the same time, because the steam can fully penetrate or heat transfer to the inside of the item, it can be sterilized for items of various shapes and sizes, including liquids, solids and gases.
3.2 Disadvantages of steam sterilization
Steam sterilization requires that the fermenter material and internal materials can withstand steam, have the certain operating flexibility, minimize internal accessories (avoid dead corners), nature of material and energy transfer performance is strong, and they can be adjusted to the certain extent in order to facilitate cleaning and reduce pollution, so once the above problems exist then they will affect the final sterilization effect to the certain extent. In addition, even if the fermenter uses steam to conduct the high-temperature sterilization, there are occasional sterilization failures in actual production - especially the sterilization failure is caused by heat-resistant spores.
Factors such as unreasonable loading, improper pretreatment of sterilizers, and insufficient exclusion of cold air will affect the completion degree of steam sterilization, and will weaken the parameters such as steam saturation degree, steam penetration capacity, steam heat conduction effectiveness and other parameters to the certain extent, making it less than the optimal effectiveness, especially when these factors are present at the same time as extremely heat-resistant microorganisms. There is a high probability that sterilization will fail.
Bacillus, especially super thermophilic spores, are extremely resistant to temperature. When spores form, they synthesize special enzymes that are more resistant to heat than those in the propagule. The core and cortex of spores contain a large amount of pyridine dicarboxylic acid (DPA), which accounts for 5%-15% of the dry weight of spores, and is a specific component of spores, which is absent in bacterial propagule and other biological cells. DPA can make spore enzymes extremely stable in a way that is not yet clear. During spore formation, DPA is quickly synthesized and heat resistance is also obtained.
Therefore, even under ideal condition, the steam killing of spores also has certain limitations, not to mention the actual steam sterilization operation is difficult to reach the most ideal theoretical degree, so in reality, the fermenter after steam sterilization will still appear microbial pollution, of which the most frequent situation is heat-resistant spores pollution.
One of the most effective ways to kill spores is Sporicide treatment. Sporicide is a foreign word, it is the translation of the English Sporicide, meaning medicament which can kill "spore". Because spore represents both gemma and spores, spores are also one kind of common highly resistant microbial species, sporicide is translated as sporicide, but its most reasonable explanation should be medicament which can kill gemma.
As it can be seen from the name, sporicide can effectively kill spores. Therefore, before steam sterilization is conducted to fermenter, sporicides can be used to pre-disinfect the fermenter to eliminate possible spore contamination, which will effectively ensure the success rate of steam sterilization. In addition, the use of sporicide can effectively solve the pollution of spores in the links that cannot withstand high temperature steam.
Oxytech, which comes from Germany, is an excellent sporicide and sterilizer that effectively kills all types of microorganisms, including heat-resistant spores. Oxytech is manufactured by a special composite process with multiple mechanism bactericidal effects, so one of its unique advantages is that it can achieve complete killing of spores at a low concentration of medicament, so that it also has good material compatibility and control the corrosion at a very low level. After its role is completed, it is decomposed into water and oxygen, ecological safety, will not affect the subsequent fermentation work, and protect the occupational health of the operator.
Fermenter is a very important equipment in the process of fermentation production, and the sterilization of fermenter is the key link to ensure the efficient conduct of subsequent microbial culture and fermentation. However, just ensuring that the operation is properly designed and scientific is not ready to work on all microorganisms. Some external dust, bacterial spores or more resistant bacteria such as heat-resistant spores will constitute a greater obstacle to the fermentation tank sterilization, then it is necessary to choose the appropriate sterilization methods and tools to ensure the sterilization effect.
For highly resistant microorganisms such as spore,non-spore bacteria,etc, non-temperature sterilization methods such as chemical sterilization, ultraviolet radiation,etc can be adopted. Among them, chemical sterilization is the most commonly used, and its principle is to use a solution containing chemical disinfectants to destroy the DNA double strand synthesis of microorganisms, so as to achieve the effect of sterilization. In addition, it is necessary to choose a suitable way to solve the high resistance pollution such as heat-resistant spores, which is used to make up for the possible shortcomings and blind areas of steam sterilization in practical operation, and finally achieve the successful sterilization of the fermenter.
When ensuring the effect of fermenter sterilization, we should also pay attention to the impact on the environment. Choosing the appropriate sterilization means can reduce the consumption of energy and materials, and reduce the pollution to the environment. Therefore, in the sterilization process, various factors should be comprehensively considered according to the specific production requirements and actual situation, and a reasonable sterilization plan and operation process should be formulated, so as to achieve efficient, safe and environmental protection of fermenter sterilization.