In industrial production, the method of adjusting pH is not just acid-base neutralization, because although acid-base neutralization can neutralize the excess alkali present in the culture medium, it cannot prevent the continuous acid-base changes that occur during the metabolic process. . Even continuous measurement and adjustment are futile because they do not fundamentally improve metabolic conditions. Because the fundamental cause of pH changes during the fermentation process is the result of microbial metabolism of nutrients, the fundamental measures to adjust and control pH should mainly consider the ratio of physiological acidic substances to physiological alkaline substances in the culture medium, and then further improve it through intermediate feeding. be controlled.
❶Feeding is not just controlled by adding acid and alkali. It can be controlled by physiological acidic and physiological alkaline substances. These substances can not only adjust the pH, but also supplement the nitrogen source.
When the pH and amino nitrogen content are low, add ammonia water;
When the pH is high and the amino nitrogen content is low, ammonium sulfate is added.
❷Sugar supplementation determines the sugar supplementation rate based on changes in pH, while constant-rate sugar supplementation controls the pH by adding acid and alkali.
◆PH control method
❶Adjust the pH of the base material. If the base material contains corn steep liquor, the pH will be acidic and the pH must be adjusted. To control the pH after disinfection at 6.0, the pH before disinfection often needs to be adjusted to 6.5~6.8.
❷Add substances to maintain pH, such as CaCO3, or reagents with buffering capabilities, such as phosphate buffer, into the basic material.
❸Adjust pH by feeding. During the fermentation process, feed is added according to sugar nitrogen consumption needs. When there is no conflict between feeding and adjusting pH, feed feeding is used to adjust pH. L
•Adjust the sugar supplement rate and air flow to adjust PH
•When NH2-N is low and PH is low, add ammonia water
•When there is a conflict between feeding and pH adjustment, add acid and alkali to adjust the pH