SU1433974A1 - Apparatus for automatic control of concentration of biocarbonate ions and total carbonate concentration in cultivation of microorganisms - Google Patents

Abstract

The invention relates to the microbiological industry and is aimed at improving the accuracy of the measurement of bicarbonate and total carbonate concentration in the fermentation medium during the cultivation process. microorganisms. The electrode sensor is made on the basis of a gas-sensitive Severinghaus electrode and placed in a fermentation medium. To measure the total carbonate concentration in a local volume near the gas permeable membrane of the sensor, 3 are created by electrolysis. Under these conditions, 99% of the bicarbonate ions are transferred to free carbon dioxide and the sensor output will be proportional to the total carbonate concentration. By determining the concentration of bicarbonate ions, electrolysis is stopped and the concentration of free carbon dioxide in the fermentation liquid is measured by a sensor. This value is subtracted from the previously measured total carbonate concentration, and thus the concentration of bicarbonate ions is obtained. 2 ill., 1 tab. with (L

Description

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The invention relates to: the microbiological industry and can be used in the control and regulation of the cultivation processes of microorganisms.

The purpose of the invention is to improve the accuracy of measurement of bicarbonic and total carbonate concentrations.

The total carbonate concentration (C) in the fermentation liquid is equal to the sum of concentrations of dissolved carbon dioxide (COi) and bicarbonate ions (HCOp, i.e.

(O- (CO,) + (NSO).

The essence of the invention is that a sensor is immersed in a liquid to measure the total carbonate concentration in the fermentation liquid.

rSOL and in the local area near

sensor membranes are created; 3, At this pH, more than 99% of the bicarbonate ions are converted to free acid, the concentration of which is measured by the pCO sensor, i.e. the output I of the sensor is proportional to the total carbonate concentration. To determine the bicarbonate ion in the fermentation liquid, the pCO sensor measures the value (CO) in the liquid without converting bicarbonate ions to carbon dioxide, and the concentration of bicarbonate ions is calculated using the above formula, taking into account the previously measured value (C).

FIG. 1 is a schematic diagram of the proposed device; in fig. 2 - a fragment of the gas-sensitive electrode shown in figure 1 ..

Sensor 1 of the device is made on the basis of a gas-sensitive Severinghaus electrode and is placed in a fermentation medium. Channels 2 serve to periodically replace the electrolyte; in step 3, the gas-permeable membrane of the sensor 1 is made of a polymer material. On the mebran 3 by vacuum spraying one side, a conductor u is applied: and a gold layer 4 of minimal density. The cathode 5 is mounted on a holder. 6 attached to the sensor body 1 parallel to the membrane 3 at a distance sufficient for free exchange of fermentation liquid.

The layer 4 on the membrane 3 and the cathode 5 are electrically connected, respectively, with positive and negative

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poles of the source 7 of direct current through the switch 8. Sensor 1 is connected to a high-resistance converter 9, the output of which is connected in series with the switch 10, the storage unit 11 and the computing unit 12. The outputs of the program block 13 are connected to the inputs of the switch 8, switch 10 and computing unit 12.

The device operates cyclically in two modes (A and B).

In mode A, a constant current source 7 is switched on. The current source 7 is set at 1-2 mA. At the surface of the gas-permeable membrane 3, an excess of hydrogen ions is formed as a result of electrolysis, causing a decrease in the pH of the fermentation liquid in the region near the gas-sensitive membrane. In this area, the bicarbonate ions of HCO are converted to free carbon dioxide CO, the concentration of which is measured by sensor 1. The measured signal proportional to the total carbonate concentration is converted by converter Y and through switch 10 and storage unit 11 enters the computing unit 12 (signal ot,).

In mode B, the direct current source is turned off, the concentration of free carbon dioxide at the sensor membrane becomes equal to the concentration of water-containing carbon dioxide in the fermentation medium. The measured signal through the converter 9, the switch 10 and the storage unit 11 enters the computing unit 12, where it is subtracted from the previously measured total carbonate concentration. The calculated value is equal to the concentration of bicarbonate ions (signal (S).

The software unit 13 provides the specified switching mode and synchronization of the subtraction procedure taking into account the dynamic characteristics of the gas sensitive electrode.

The calibration of the automatic control system is carried out by immersing the sensor in aqueous solutions containing sodium bicarbonate, the concentration of which is also determined by a quantitative analysis method.

The table shows the comparative results of measurements with the proposed and known devices in the fermentation liquid in the fermenter — capacity P, 25 m, where the producer of streptomycin is grown on a complex medium.

As can be seen from the table, the proposed device in comparison with the known one allows to obtain a relative error in determining the carbonate concentration of not more than 4%, which is 5 times lower.

The use of the proposed device provides continuous precise control of bicarbon, atomic and total carbonate concentrations directly in the fermentation medium, which allows creating optimal conditions for biosynthesis by maintaining the specified parameter at a given level.

Claims (1)

Invention Formula .. Device for automatic control of bicarbonate ion concentration and total carbonate concentration 25 ten 15 0 five in the process of cultivating microorganisms, containing a gas sensitive pCOj electrode with a pH-metric indication and a gas-permeable membrane, connected to a high-resistance transducer, characterized in that, in order to improve the measurement accuracy, it contains a source of direct current with a switch, an output switch of the electrode and connected in series the memory and computational units, the program control unit and the cathode located outside the electrode and connected to the negative pole of the source the direct current, wherein the outer side of the gas permeable membrane - conductive and connected to the positive pole of a constant current, and the program control unit is connected to the switch, the switch and the computer unit, wherein the input switch is coupled to the output of a high-resistance transducer. Carbonate concentration, measured by the device, mM proposed famous 24 48 72 96 20 44 68 2.68 3.81 4.72 3.42 3.82 2.93 18.80 3.04 3.18 5.24 2.75 4.52 3.59 23.15 The measurement error calculated with respect to the concentration determined by the quantitative analysis method for the device known proposed 2.59 3.71 4.60 3.53 3.75 3.04 9.20 17.6 15.6 18.3 18.9 23.5 18.1 20.6 3.08 2.70 2.61 3.12 1.87 3.62 1.56 1 FIG. 2