In the process of biological fermentation, pH value and dissolved oxygen are key parameters that affect microbial growth and fermentation efficiency. Their monitoring and regulation need to be carried out in conjunction with the standardized operation of the entire bioreactor process.
The core equipment for biological fermentation is a glass bioreactor (often referred to as a "glass tank"). Although it is called a "high-temperature bioreactor", the actual fermentation culture temperature is 30-35 ℃. "High temperature" only refers to the sterilization requirement of withstanding 121 ℃ for half an hour - during sterilization, the reactor (containing culture medium, including yeast paste, yeast extract, glucose water and other nutrients) needs to be sent to the sterilization pot, and the electrode joints need to be wrapped in tin foil to prevent water from entering. Before sterilization, the electrodes need to be installed in advance (pH electrodes need to be calibrated in advance, dissolved oxygen electrodes need to be calibrated after sterilization).
After sterilization, key parameter calibration and adjustment need to be completed first: dissolved oxygen calibration requires opening ventilation and stirring, adjusting to the appropriate speed, and setting the instrument to 100% calibration; The pH value is prone to acidic after sterilization (usually around 6.0 or slightly higher), and needs to be adjusted to neutral by adding alkali through a reserved interface. Subsequently, sterile inoculation should be carried out: a flame ring should be added to the inoculation port and ignited. After pouring in the bacterial strain, the interface should be tightly sealed to ensure sterility, and then the flame ring should be removed to avoid contamination by miscellaneous bacteria.
After inoculation, there may be fluctuations in dissolved oxygen levels during the fermentation stage (which is a normal phenomenon for microbial growth requirements), and it is necessary to stabilize the parameters through feeding regulation (mostly sugar supplementation, but can also be supplemented with nitrogen sources, carbon sources, and other nutrients); During the growth process, it may be necessary to supplement acid or alkali through reserved interfaces to maintain pH stability. In addition, the electrode installation of the glass reactor is vertically inserted, and the interface type needs to match the scenario: K8S and S8 interfaces do not have temperature function, while VP interface has temperature monitoring, which can be selected according to needs.