Workflow for microbial fermentation

"Line-height: 1.5;"What is the workflow of microbial fermentation? In fact, we have seen the decay of apples and other foods are also microbial fermentation, but here we refer to the use of microorganisms, under the right conditions, the raw materialthrough through a specific metabolic pathway into the products that humans needSo what are the main steps in this process?span style"line-height: 1.5; """text-align: center;" sspan style"line-height: 1.5; "img src""alt"" microbial fermentation Workflow "title" "Microbial fermentation workflow"first, the cultivation of bacteria:is the natural selection of bacteria: that is, in the production process, without artificial treatment, the use of the spontaneous mutation of the bacteria, so as to select the process of good bacteria, called natural breedingThere are often two possibilities for spontaneous mutations in bacterial species: the decline of the bacteria, the decline of production performance, or the metabolism is more vigorous, the production performance is improvedWith practical experience and good observation staff, we can take advantage of spontaneous mutations and the changes in the characteristics of the bacteria, the selection of good strainsFor example, during the glutamate fermentation process, the bacteria resistant to phages were isolated from the fermentation fluid contaminated with the phageFor example, in the production of antibiotic fermentation, from a batch of high-yielding fermentation liquid sampling to separate, often can obtain a more stable high-yield strainsHowever, the frequency of spontaneous mutation is low, the possibility of good characteristics is small, it takes a considerable time to achieve resultsthe second is bacterial mutagenic breeding: mutagenic breeding refers to the artificial method of treating microorganisms, making them mutate, and then screening out the required mutant strains for production and scientific experimentsCompared with other breeding methods, mutagenic breeding has the advantages of simple operation, speed and great results, and is still an important and widely used microbial breeding methodMutagenic breeding consists of three parts: departure bacteria selection, mutagenic treatment and screening of mutant strainsthe selection of the second, the species:bacteria after mutagenesis treatment, will produce a variety of mutation typesHow to choose the required type of mutation? Generally through the first sieve and resision two stagesThe screening of high-yielding mutant strains of penicillin is illustrated below After diluting the mutagenesis-treated bacteria at a certain concentration, apply it to a flat medium After culture, a single colony is selected on to the oblique medium, after culture, and then the ramp on the colonies one by one inoculated into the shaker bottle, oscillating culture to measure their antibiotic efficacy This is the first sieve The first sieve obtained more than 10% of the control effect price of the bacteria, and then resision The process of resisioning is basically the same as the initial sieve, except that the single colony on the slope is generally inoculated into three shakers to obtain the average price Resieve can be performed 1 to 3 times The high-yielding stable strains screened from this also have to go through small or even medium-sized tests before they can be used in fermentation production third, medium configuration: (1) raw materials: carbon source, nitrogen source, growth factor, inorganic salt and water (2) Principle: the purpose should be clear, nutrition should be coordinated, PH should be appropriate fourth, sterilization: fermentation process can not have hybrid contamination, not only the culture of sterilization, but also the fermentation device sterilization, through the air also to sterilize sterilization not only to kill hybrid cells, but also to kill spores and spores Fifth, Expand culture and inoculation: expanded culture can shorten the adjustment period of microbial growth. sixth, microbial fermentation process: is the central stage of fermentation The key is to control fermentation conditions such as temperature, pH, dissolved oxygen, ventilation and speed The reason is that changes in environmental conditions will not only affect the growth and reproduction of bacteria, but also affect the formation of metabolites of the species The factors that affect the fermentation process affect the fermentation process are mainly in the following aspects 1, temperature control: the effects of temperature on microorganisms are many First, temperature affects the activity of the enzyme In the optimum temperature range, the rate of fermentation reaction accelerates as the temperature increases, the growth and metabolism of bacteria increase When the optimum temperature range is exceeded, as the temperature increases, the enzyme quickly inactivates, the bacteria age, the fermentation cycle is shortened, and the yield decreases Temperature can also affect the way biosynthesis is made For example, golden streptomycin has a strong ability to synthesize kinymycin at less than 30 degrees C, but only tetracycline is synthesized instead of kinythromycin when the temperature exceeds 35 degrees C In addition, the temperature also affects the physical properties of the fermentation solution, as well as the decomposition and absorption of nutrients by the bacteria Therefore, to ensure a normal fermentation process, it is necessary to maintain the optimum temperature However, the optimum temperature required for bacterial growth and product synthesis is not necessarily the same The most suitable growth temperature for gray streptomycin, for example, is 37 degrees C, but the optimum temperature for the production of antibiotics is 28 degrees C In general, it is necessary to determine the optimum temperature of each fermentation stage of different species through experiments and to adopt segmented control 2, suitable pH: pH can affect the activity of enzymes, as well as the charge status of cell membranes If the charge condition of the cell membrane changes, the permeability of the membrane also changes, which may affect the absorption of nutrients and the secretion of metabolites by microorganisms In addition, pH also affects the decomposition of nutrients in the medium, etc Therefore, the pH of the fermentation solution should be controlled However, the most suitable pH seisps are often different in the growth stage and synthesis product stage of different species and need to be controlled separately In the fermentation process, with the use of nutrients and the accumulation of metabolites, the pH of the fermentation solution will inevitably change As urea is broken down, the concentration of NH-4 in the fermentation solution increases and the pH increases In industrial production, it is often used to add a buffer system to maintain pH in the fermentation solution, or through the intermediate filling of ammonia, urea, ammonium carbonate or calcium carbonate to control pH At present, the domestic detection of fermentation process of pH electrode, used for continuous determination and recording of pH changes, and by the pH controller to adjust the amount of acid, alkali addition 3, dissolved oxygen: oxygen supply is a key factor for aerobic fermentation In terms of the oxygen demand for glucose oxidation, 1 mol of glucose is completely oxidized and decomposed, requiring 6 mol of oxygen, and 1 mol glucose needs about 1.9 mol of oxygen when sugar is used for anabolic products Therefore, aerobic microorganisms need oxygen is very large, but in the fermentation process, the bacteria can only use dissolved oxygen in the fermentation liquid, however oxygen is difficult to dissolve in water Oxygen is 0.26 mmol/L in water at 101.32 kPa and 25 degrees C Under the same conditions, oxygen is only 0.20 mmol/L dissolved in the fermentation solution, and as the temperature increases, the solubility decreases Therefore, a large amount of oxygen must be continuously replenished to the fermentation solution, and constantly stirred, so as to improve the solubility of oxygen in the fermentation solution 4, foam: in the fermentation process, ventilation stirring, microbial metabolic process and the decomposition of certain components in the medium, etc., may produce foam It is normal to produce a certain amount of foam in the fermentation process, but too many persistent foams are not conducive to fermentation Because the foam will occupy the volume of the fermentation tank, affect the normal ventilation and stirring, and even lead to metabolic abnormalities, it is necessary to eliminate the foam There are two types of commonly used anti-foam measures: one is the installation of foam-free bezels, through strong mechanical oscillations, to promote the foam burst, and the other is the concentration of various nutrients in the fermentation liquid using antifoam nutrients, especially the concentration of carbon-nitrogen ratio, inorganic salts and vitamins, which will directly affect the growth of bacteria and the accumulation of metabolites In glutamate fermentation, changes in the concentration of NH-4 can affect metabolic pathways (see glutamate fermentation) Therefore, in the fermentation process, should also be controlled according to the specific situation In the case of the manufacture of glutamate, the regulation and control of oxygen, temperature, pH and phosphate are as follows during fermentation: (1) oxygen Glutamate production bacteria is aerobic bacteria, ventilation and stirring will not only affect the utilization rate of the bacteria on nitrogen and carbon sources, but also affect the fermentation cycle and the synthesis of glutamate Especially in the late fermentation, increasing ventilation is beneficial to the synthesis of glutamate (2) temperature The optimum temperature for the growth of the species is 30 to 32 degrees Celsius When the bacteria grow to a stable period, the appropriate temperature increase is conducive to acid production, therefore, in the late fermentation, the temperature can be raised to 34 to 37 degrees C (3)pH Glutamate produces the most suitable pH for bacterial fermentation at 7.0 to 8.0 However, in the fermentation process, with the use of nutrients, the accumulation of metabolites, the pH of the culture liquid will change constantly If ammonia is released with the use of nitrogen sources, the pH will rise, and when sugar is used to produce organic acids, the pH will decrease (4) phosphate It is necessary in the process of glutamate fermentation, but the concentration cannot be too high, otherwise it will turn to proline fermentation After fermentation, the ion exchange resin method is usually used for extraction "text-align: center;"img src""alt" "Microbial fermentation workflow" title"""microbial fermentation workflow" seventh, separation purification : fermentation engineering products metabolic products: distillation, extraction, ion exchange and other methods extracted the bacteria itself: can be used to filter, precipitation and other methods from the culture of separation microbial fermentation production level mainly depends on the genetic characteristics and culture conditions of the bacteria themselves The application scope of fermentation engineering is: (1) pharmaceutical industry, (2) food industry, (3) energy industry, (4) chemical industry, (5) agriculture: genetic modification plants; (6) Environmental protection and so on But the microbial fermentation process must pay attention to can not be infected, once infected with other strains, will not be able to grow into the products we need