Concept and characteristics of traditional fermentation engineering

Fermentation engineering refers to the use of certain specific functions of microorganisms, the use of modern engineering technology to produce products useful to human beings, or the direct application of microorganisms to industrial production processes. The contents of fermentation engineering include strain selection, culture medium preparation, sterilization, expanded culture and inoculation, fermentation process and product separation and purification. It is an important branch of the first-level discipline "Light Industry Technology and Engineering", which is the key development of the two disciplines and plays a key role in the industrialization of biotechnology. 1) "Fermentation" includes "fermentation strictly defined by microbial physiology" and "industrial fermentation", and the term "fermentation engineering" should be "industrial fermentation". (2) In industrial production, products are processed or manufactured through industrial fermentation, and the corresponding processing or manufacturing process is called "fermentation process". In order to realize industrial production, it is necessary to solve the engineering problems of industrial production environment, equipment and process control in order to realize these processes (fermentation process), so there is "fermentation engineering" (3) Fermentation engineering is a discipline to solve the engineering problems of industrial production according to fermentation technology. Fermentation engineering from the engineering point of view, the fermentation industrial process of realizing fermentation technology is divided into three stages: strain, fermentation and refining (including wastewater treatment). These three stages have their own engineering problems, which are generally called upstream, midstream and downstream projects of fermentation engineering respectively. (4) Microorganism is the soul of fermentation engineering. In recent years, the understanding of the biological characteristics of fermentation engineering has become increasingly clear, and fermentation engineering is approaching science. (5) The basic principle of fermentation engineering is its biological principle. Fermentation engineering refers to the use of engineering technology, using some functions and activities of organisms (mainly microorganisms) to separate enzymes, producing biological products useful to human beings, or directly using microorganisms to control some industrial production processes. Well-known examples are beer, fruit wine and industrial alcohol produced by yeast fermentation, cheese and yogurt produced by lactic acid bacteria fermentation, and large-scale production of penicillin by fungi. With the progress of science and technology, fermentation technology has also developed greatly, and it has entered the stage of modern fermentation engineering, which can manually control and transform microorganisms to make these microorganisms produce products for human beings. As an important part of modern biotechnology, modern fermentation engineering has broad application prospects. For example, genetic engineering is used to purposefully transform the original strain and improve its yield; Using microbial fermentation to produce drugs, such as human insulin, interferon and growth hormone. It has developed from the simple production of alcoholic beverages, acetic acid and fermented bread to an extremely important branch of bioengineering today, and has become a multidisciplinary project including microbiology, chemical engineering, genetic engineering, cell engineering, mechanical engineering and computer software and hardware engineering. Modern fermentation engineering not only produces alcoholic beverages, acetic acid, bread, but also produces insulin, interferon, growth hormone, antibiotics, vaccines and other medical and health care drugs, produces agricultural means of production such as natural pesticides, bacterial fertilizers and microbial herbicides, and produces amino acids, spices, biopolymers, enzymes, vitamins, single cell proteins and so on in the chemical industry. Broadly speaking, fermentation engineering consists of three parts: upstream engineering, midstream engineering and downstream engineering. Upstream projects include the selection of excellent seed plants, the determination of optimal fermentation conditions (pH, temperature, dissolved oxygen, nutrients) and the preparation of nutrients. Midstream project mainly refers to the technology of cultivating a large number of cells and producing metabolites in fermentor under the best fermentation conditions. There should be a strict aseptic growth environment here, including the technology of high temperature and high pressure sterilization of fermentation raw materials, fermentation tanks and various connecting pipes before fermentation begins; Air filtration technology of continuously introducing dry sterile air into the fermentation tank during fermentation; Computer control technology for controlling feeding speed according to cell growth demand during fermentation; Seed culture and production culture also have different techniques. In addition, according to different needs, batch fermentation is also classified in fermentation technology: one-time fed-batch fermentation; Fed-batch fermentation: that is, on the basis of one-time fed-batch fermentation, a certain amount of nutrients are added to further grow cells or obtained metabolites; Continuous fermentation: continuously add nutrients and take out the fermentation broth. Before any large-scale industrial fermentation, a large number of experiments must be carried out in a laboratory-scale small fermentor to obtain the kinetic model of product formation, and according to this model, the fermentation requirements of the pilot plant are designed, and finally the kinetic model of larger-scale production is designed from the pilot plant data. Due to the complexity of biological reaction, there will be many problems in the process from laboratory to pilot plant, from pilot plant to large-scale production, which is the problem of amplification of fermentation engineering process. Downstream engineering refers to the technology of separating purified products from fermentation broth, including solid-liquid separation technology (centrifugal separation, filtration separation, precipitation separation, etc. ), cell wall-breaking technology (ultrasound, high pressure shearing, osmotic pressure, surfactant, lywallzyme, etc. ), protein purification technology (precipitation, chromatographic separation and ultrafiltration, etc. ), and finally the product packaging and processing technology (vacuum drying and freeze drying, etc.). In addition, in the fermentation industry that produces drugs and food, it is necessary to strictly abide by the cGMPs regulations promulgated by the US Federal Food and Drug Administration, and regularly accept the inspection and supervision of relevant competent departments.