WO2010135853A1

WO2010135853A1 - Fermentation process controlling method and fermentation process controller

Info

Publication number: WO2010135853A1
Application number: PCT/CN2009/000598
Authority: WO
Inventors: 蒋俊峰; 杨宏伟; 范顺杰; 贺伯特·格里布; 孔兵; 卓越
Original assignee: 西门子公司
Priority date: 2009-05-27
Filing date: 2009-05-27
Publication date: 2010-12-02

Abstract

The present invention discloses a fermentation process controlling method, comprising determining the current stage of fermentation process based on the acquired measurement of cell characteristics, controlling nutrient feed rate in fermentation process on the basis of controlling algorithm corresponding to determined fermentation phase. The present invention also discloses a fermentation process controller. The controlling of nutrient feed rate can be accomplished accurately and conveniently by employing the method and the device defined in the present invention.

Description

Description of a fermentation process control method and a fermentation process controller

The invention relates to a fermentation technology, in particular to a fermentation process control method and a fermentation process. Background technique

Fermentation is an important process in the realization of biochemical engineering, and the products obtained by fermentation can be widely used in the fields of pharmaceuticals, food and beverages, energy, and water treatment. In order to increase production, reduce costs and better comply with the requirements of the relevant regulations, it is often necessary to automate the fermentation process. However, due to the complexity of the fermentation process itself, the degree of automation of the fermentation process is far less than that of chemical and petrochemical processes.

In the fermentation system, the fermenter operates in a fed-batch fermentation mode with a feed line, on-line sensors, and some necessary control loops.

In the prior art, closed-loop control of common parameters in the fermentation process has been achieved by using corresponding electrodes and single and unique closed-loop feedback control methods. The common parameters mentioned here include: temperature, pH, and dissolution. Oxygen, etc. However, due to the lack of some key biological state variables, such as online measurements of biomass concentration and nutrient concentration per unit volume, the nutrient feeding process (by promoting nutrients such as glucose or nitrogen for fermenters) Cell growth and metabolite production) are usually in open loop control, ie by manual or according to a predetermined feeding strategy, such as linear fed or exponential feeding.

Studies have shown that the quality of the fermented product is related to factors such as the specific growth rate of the cells, and the specific growth rate of the cells is related to the nutrient feeding rate, that is, if the nutrient feeding rate can be well controlled, The quality of the fermented product is greatly improved. To this end, various control methods have been proposed in the prior art, such as - The specific growth rate of the cells is controlled by continuously changing the nutrient feeding rate, wherein the nutrient feeding rate is predetermined and gradually decreased according to a continuous function, that is, pre-specified nutrient feeding rate Change track. This method attempts to control the specific growth rate of the cells to a suitable point without feedback, but this method is severely affected by external disturbances, because the change in nutrient feed rate is pre-defined, once If there is interference, the actual change will deviate from the specified situation.

As another example, the specific growth rate is calculated based on the co ₂ content in the exhaust gas discharged from the fermentation process measured online, and the specific growth rate is maintained at a stable level by adjusting the feed rate of the carbon source. However, this method needs to rely on the co ₂ content measured online, which is large in noise, easily causes large batch fluctuations, and may even cause feeding errors. Summary of the invention

In view of the above, it is a primary object of the present invention to provide a fermentation process control method capable of accurately and conveniently controlling the feed rate of nutrients.

Another object of the present invention is to provide a fermentation process controller that is capable of accurately and conveniently controlling the feed rate of nutrients.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A fermentation process control method comprising:

Based on the obtained cell characteristic measurement results, the fermentation period currently in the fermentation process is determined; and the nutrient feeding rate in the fermentation process is controlled according to a control algorithm corresponding to the determined fermentation period.

Preferably, the determining, according to the obtained cell characteristic measurement result, that the fermentation period currently in the fermentation process comprises:

Determining whether the cell density measurement result and the cell distribution measurement result can be simultaneously obtained; if it can be simultaneously acquired, determining the current fermentation period of the fermentation process by performing three-dimensional spatial tracking analysis on the cell density measurement result and the cell distribution measurement result; If only the cell density measurement results are obtained, the current fermentation period of the fermentation process is determined by trend analysis of the cell density measurement results.

Preferably, the trending analysis of the cell density measurement results to determine that the fermentation period currently in the fermentation process comprises:

From the beginning of the fermentation process, the cell density measurement results at a specified time point are continuously fitted to a straight line, and the fitted linear equation is obtained;

Using the line equation, the cell density measurement results at each specified time point acquired after the A specified time points are verified, and the obtained cell density measurement results at each specified time point are calculated. Using the straight line equation to calculate a difference in cell density measurements at the specified time point, and comparing each difference with a predetermined limit level, if consecutive B differences are greater than the limit level , determining that the current fermentation period has been transferred from the delay period to the exponential growth period, and determining the time point corresponding to the first difference greater than the limit level as the inflection point;

Starting from the inflection point, fitting the cell density measurement results of the C consecutively obtained time points to an exponential curve, and obtaining a fitted exponential equation;

Using the exponential equation, the cell density measurement results at each specified time point acquired after the C specified time points are verified, and the obtained cell density measurement results at each specified time point are calculated and Using the exponential equation to calculate a difference in cell density measurements at the specified time point, and comparing each difference to a predetermined limit level, if consecutive D differences are greater than the limit level , determining that the current fermentation period has shifted from the exponential growth phase to the stationary phase; the A, B, C, and D are positive integers greater than one;

Alternatively, the trending of the cell density measurement results to determine that the fermentation process currently in the fermentation period comprises:

From the beginning of the fermentation process, the continuously obtained E group cell density measurement results are respectively fitted into a straight line; the E is a positive integer greater than 1; wherein, the cell density measurement results included in each group of cell density measurement results are included The same number; And, each time the fitting of the set of cell density measurement results is completed, comparing the slope of the fitted straight line with a preset first threshold value, if the slope of the fitted straight line is greater than the first Threshold, determining that the current fermentation period has been transferred from the delay period to the exponential growth phase; thereafter, comparing the slope of the line fitted according to the next set of cell density measurements with a predetermined second threshold, if The slope of the fitted straight line is less than the second threshold, and it is determined that the current fermentation period has shifted from the exponential growth phase to the stationary phase.

Preferably, the three-dimensional spatial tracking analysis of the cell density measurement and the cell distribution measurement results to determine that the fermentation period currently in the fermentation process comprises:

From the beginning of the fermentation process, the obtained cell distribution measurement results and the cell density measurement results at each specified time point are plotted in a three-dimensional space; the cell distribution measurement results in a proportion of large cells;

Starting from the second specified time point, calculate the proportion of large cells at each specified time point and the difference between the cell density measurement and the ratio of large cells and cell density measurements at the previous specified time point, and Comparing the calculated difference with a preset first combined threshold, if the consecutive F differences are greater than the first combined threshold, determining that the current fermentation period has been transferred from the delay period to the exponential growth period, And determining a time point corresponding to the first difference greater than the first combination threshold as an inflection point;

Starting from the inflection point, calculating the ratio of the large cells at each specified time point and the difference between the cell density measurement and the ratio of the large cells at the previous specified time point and the cell density measurement, and The calculated difference is compared with a preset second combination threshold. If the consecutive G differences are greater than the second combined threshold, it is determined that the current fermentation period has been transferred from the exponential growth period to the stationary period; Both F and G are positive integers greater than one.

In addition, before determining the fermentation period currently in the fermentation process based on the obtained cell characteristic measurement result, the method further includes:

The obtained cell characteristic measurement result is preprocessed, the abnormal point is identified, and the culling is performed. Preferably, controlling the nutrient feeding rate in the fermentation process according to a control algorithm corresponding to the determined fermentation period comprises:

The nutrient feed rate was calculated as follows:

F _s (t) = F _s0 (t) + K _c [e{t) + - [e{t)dt ; the e(i) =〃- /

Wherein the / represents a specific growth rate calculated using the obtained cell density measurement result; the ^ represents a specific growth rate predetermined value; the indicating the calculated specific growth rate and the specific growth rate predetermined value The difference between ^; the sum is an adjustable parameter; the representation of the nutrient feed rate; the F _Q ( ) represents the forward feedback portion, calculated using a control algorithm corresponding to the determined fermentation period inferred.

The calculation of the specific growth rate / i includes: μ = -^ , wherein the said cell density measurement result.

X dt

The calculation method of the forward feedback portion F _iQ (i) includes:

When the determined fermentation period is a delay period, the / ^ (0 = ^ + ^(0 ; wherein the sum is an adjustable parameter;

When the determined fermentation period is an exponential growth phase, the (^) = ^: ^ _{2 ;} wherein; ^ represents a cell density measurement result, the ^: is an adjustable parameter, and the / / _ρ2 represents a predetermined growth rate of the exponential growth phase;

When the determined fermentation period is a stationary period, the ^^^α + Ζ^^^Γ - Ο wherein the α represents an initial nutrient feeding rate during the stationary period, the tunable parameter, ^ ₃ denotes a predetermined value of the specific growth rate of the stationary period, the indicating the cell density measurement result, the ί ₂ indicating the start time of the stationary period, and the ₂ indicating the cell density measurement at the time ί ₂ .

A fermentation process controller, including - a fermentation period identification module, configured to determine a fermentation period currently in the fermentation process based on the obtained cell characteristic measurement result;

An algorithm selection module is configured to select a control algorithm corresponding to the determined fermentation period; and a control algorithm module for controlling the nutrient feeding rate in the fermentation process according to the selected control algorithm.

Preferably, the fermentation period identification module comprises:

a data pre-processing sub-module, configured to pre-process the obtained cell characteristic measurement result, identify an abnormal point and perform culling;

Determining a sub-module for determining whether the obtained cell characteristic measurement result includes only the cell density measurement result or both the cell density measurement result and the cell distribution measurement result, and notifying the determination result to the trend analysis and the fermentation period identification sub-module;

The trend analysis and fermentation period identification sub-module is configured to determine a current state of the fermentation process by performing trend analysis on the cell density measurement result when the determination result includes only the cell density measurement result in the obtained cell characteristic measurement result. At the fermentation stage; when the result of the determination is that the obtained cell characteristic measurement result includes both the cell density measurement result and the cell distribution measurement result, the fermentation is determined by performing three-dimensional spatial tracking analysis on the cell density measurement result and the cell distribution measurement result. The process is currently in the fermentation period.

Preferably, the fermentation process controller further includes:

Deriving a model module for calculating a specific growth rate μ, μ = -− using the obtained cell density measurement result, the said cell density measurement result, and calculating the specific growth rate〃

X dt

Provided to the control algorithm module;

The control algorithm module includes:

a first calculation sub-module for calculating a difference between a specific growth rate from the derivation model module and a predetermined value of a pre-stored specific growth rate; 根据 according to the determined fermentation period, the value of the / ^ Will also be different; a second calculation subunit for calculating the nutrient feed rate in the following manner:

F _s (0 = F _s0 (t) + K _c [e(t) + 丄fe{t)dt]; wherein, the sum is an adjustable parameter; the said represents a nutrient feeding rate; (0 indicates the forward feedback portion;

When the determined fermentation period is a delay period, the said. (0 = ^ +^(0; where , and ^ are tunable parameters;

When the determined fermentation period is an exponential growth phase, the ^W ^^; wherein, the cell density measurement result, the adjustable parameter, the predetermined growth rate of the index growth period is a predetermined value ;

When the determined fermentation period is a stationary period, the _D o) = _a + ^ _{/> 3} ( - _ί2 ) _; wherein the α represents an initial nutrient feeding rate during the stationary period, and the The parameter is adjusted, the ₃ indicates a predetermined value of the specific growth rate of the stationary phase, the indicating the cell density measurement result, the ^ indicates the starting time of the stationary period, and the _1⁄2 indicates the cell density measurement at the time of ί ₂ .

It can be seen that, by using the technical scheme of the invention, based on the obtained cell characteristic measurement results, the fermentation period currently in the fermentation process is identified, and different control algorithms are respectively adopted for different fermentation periods, thereby controlling the nutrient supplement in the fermentation process. The feed rate is such that the nutrient feeding rate in different fermentation periods is always at an optimal value, and the accuracy of the feeding is ensured; moreover, the solution of the invention is simple to implement, convenient to popularize, and can be applied to various fermentation processes. For example, E. coli, yeast, and fermentation of animal cells, etc., and can significantly improve product quality and fermentation efficiency. DRAWINGS

The above and other features and advantages of the present invention will become apparent to those skilled in the <RTIgt 1 is a flow chart of an embodiment of a fermentation process control method of the present invention;

2 is a schematic diagram of a fermentation period included in the existing fermentation process;

3 is a schematic diagram of an implementation principle of a method 1 according to an embodiment of the present invention;

4 is a schematic diagram of an implementation principle of a method 2 according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a 3D space in the method 3 according to the embodiment of the present invention;

6 is a schematic structural view of an embodiment of a fermentation process controller of the present invention.

detailed description

In view of the problems existing in the prior art, the present invention proposes a novel fermentation process control method, which uses the obtained cell characteristic measurement results (such as cell density measurement results and cell distribution measurement results) to determine the fermentation process currently in the fermentation process. Period, and different control algorithms are used for the different fermentation periods determined to control the nutrient feeding rate during the fermentation process. Among them, the exponential growth period and the stationary period adopt adaptive control.

In order to make the objects, the technical solutions and the advantages of the present invention more comprehensible, the present invention will be further described in detail below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

1 is a flow chart of an embodiment of a fermentation process control method of the present invention. As shown in Figure 1, it includes:

Step 101: Determine the current fermentation period of the fermentation process based on the obtained cell characteristic measurement results.

Figure 2 is a schematic diagram of the fermentation period included in the existing fermentation process. As shown in Figure 2, for a complete fermentation process, there are four different fermentation periods, including the delay period, the exponential growth phase, the stationary phase, and the death phase. Since in practice, the required fermentation process is usually completed before entering the death period, that is, the fermented product has been obtained, therefore, only the delay period, the exponential growth period, and the smoothness are determined in the embodiment of the present invention. Period, and will not involve the death period.

Cell characteristics, such as cell density and cell distribution, can characterize the cells themselves during different fermentation phases Inherent physiological changes, therefore, by analyzing the measurement of cell characteristics, different fermentation periods can be determined.

Wherein, if the cell density measurement result and the cell distribution measurement result are correctly obtained, the three-dimensional spatial tracking analysis can be performed on the cell density measurement result and the cell distribution measurement result to determine different fermentation periods, and the specific implementation is as shown in the following method 3. If the cell distribution measurement result cannot be obtained correctly, that is, only the cell density measurement result can be obtained, the different fermentation period can be determined by performing trend analysis on the cell density measurement result, and the specific method is as follows:

2 is shown.

Method 1: Different fermentation periods were determined by trend analysis of cell density measurements.

First, the obtained cell density measurement result is preprocessed, and the abnormal point is identified and rejected. How to perform preprocessing is a prior art, and will not be described again. Then, from the beginning of the fermentation process, the cell density measurement results (such as 4, and the measurement time interval between each two measurement results greater than 2 minutes) are continuously acquired at a plurality of specified time points. Straight line, get the fitted linear equation, how to fit into the existing technology, no longer repeat them. In addition, the above cell density measurement results are usually measured by an online density sensor. If there is no online cell density sensor, it can also be manually measured by offline method, such as by sampling, or by using the co ₂ measured by the exhaust gas analyzer. The concentration of 0 ₂ is directly calculated.

Then, using the fitted linear equation, the cell density measurement results at each specified time point acquired after the above four specified time points are verified, and the cells actually obtained at each specified time point are calculated. The difference between the density measurement and the cell density measurement at the specified time point calculated using the fitted line equation, and each difference is a predetermined limit level (eg, the online density sensor error) Twice) For comparison, if multiple consecutive differences (such as 3) are greater than the limit level, it is determined that the current fermentation period has been transferred from the delay period to the exponential growth period, and the first difference is greater than the limit level. The time point corresponding to the value is determined as the inflection point.

The above specified time point refers to the assumption that the online density sensor outputs cell density every three minutes. Measurement results, then each cell density measurement can be used, or only some of the cell density measurements specified therein can be used. Subsequent similar situations will not be described again.

Then, starting from the determined inflection point, the index curve is fitted by the cell density measurement results of a plurality of consecutively selected time points (eg, 4), and the fitted exponential equation is obtained as follows:

_y = a V + ( (1) Then, using the fitted exponential equation, the cell density measurement results obtained at each specified time point are subsequently verified, and each of the obtained time points is calculated. The difference between the cell density measurement and the cell density measurement at the specified time point calculated using the fitted exponential equation, and each difference to a predetermined limit level (eg, an online density sensor) If the difference is twice (for example, three), the difference is greater than the limit level, then it is determined that the current fermentation period has been transferred from the exponential growth period to the stationary period.

FIG. 3 is a schematic diagram of an implementation principle of the method 1 according to an embodiment of the present invention. As shown in Fig. 3, the dotted line indicates the fitted straight line, indicating the inflection point.

Method 2: Determine the different fermentation periods by performing a slope change trend analysis on the cell density measurement results.

In this method, the cell density measurement results are linearly fitted continuously using a moving window measured at a fixed interval. That is: from the beginning of the fermentation process, the continuously acquired sets of cell density measurements are respectively fitted into a straight line, each group including the same number of (for example, 4) cell density measurements (every two The measurement interval between measurement results is greater than 2 minutes). In practical applications, it is assumed that the online density sensor measures 12 cell density measurements, which are numbered 1 to 12 in order of increasing time, then 1 to 4 can be used as the first group, and 5 to 8 can be used as the second group. 9 to 12 as the third group; or, 1 to 4 may be used as the first group, and then after 2 points, 7 to 10 are taken as the second group. In short, the specific grouping manner is not limited.

The slope of the fitted straight line is compared with a preset first threshold value each time a fitting of a set of cell density measurement results is completed, and if the slope of the fitted straight line is greater than the first threshold value, determining the current The fermentation period has been transferred from the delay period to the exponential growth phase; after that, it will be based on the next The slope of the line fitted by the group cell density measurement is compared with a preset second threshold. If the slope of the fitted line is less than the second threshold, it is determined that the current fermentation period has been transferred from the exponential growth period. Smooth period.

FIG. 4 is a schematic diagram of an implementation principle of a method 2 according to an embodiment of the present invention. As shown in FIG. 4, a broken line 1 indicates a straight line fitted when the fermentation process is in a delay period, a broken line 2 indicates a first threshold, and a broken line 3 indicates a straight line that has been fitted after a transition from a delay period to an exponential growth period. ^ indicates the inflection point.

Method 3: Different fermentation periods were determined by 3D spatial tracking analysis of cell density measurements and cell distribution measurements.

During the fermentation process, during the delay period, as the cells are adapting to the new environment and begin to develop, the proportion of large cells will decrease. After entering the exponential growth phase, the proportion of large cells will gradually increase due to the rapid division of cells. Moreover, when the exponential growth phase is about to end, the proportion of large cells will reach a maximum; in the stationary phase, the cell growth rate is approximately equal to the cell death rate, and the proportion of large cells will begin to decrease. Therefore, by analyzing the proportion of large cells and the changes in cell density, different fermentation periods can be determined. Specific implementations include:

First, from the beginning of the fermentation process, the proportion of large cells obtained at each specified time point and the cell density measurement are plotted in the 3D space. As shown in FIG. 5, FIG. 5 is a schematic diagram of a 3D space in the method 3 according to the embodiment of the present invention.

From the second time point, calculate the difference between the proportion of large cells at each specified time point and the difference between the cell density measurement and the ratio of large cells at the previous specified time point and the cell density measurement, and The calculated difference is compared with a preset first combined threshold; obviously, in 3D space, the calculated difference between the proportion of large cells and the cell density measurement will be a vector, and the first combined threshold Is also a vector; if a plurality of consecutive differences (such as 3) are greater than the first combined threshold, it is determined that the current fermentation period has been transferred from the delay period to the exponential growth period, and the first one is greater than the first combined threshold The time point corresponding to the difference is determined as the inflection point.

Then, starting from the inflection point, calculate the proportion and size of the large cells at each specified time The difference between the cell density measurement and the ratio of the large cells at the previous time point and the cell density measurement, and compares the calculated difference with a preset second combination threshold, if multiple consecutive (eg If the difference is greater than the second combined threshold, it is determined that the current fermentation period has shifted from the exponential growth phase to the stationary phase.

Step 102: Calculate the specific growth rate.

In this embodiment, the cell density measurement can be used to calculate the specific growth rate / as follows:

1 dX; , μ = ",)

X dt

Where, it represents the measurement of cell density, or the concentration of biomass in a unit volume. Step 103: Using the calculated specific growth rate, the nutrient feeding rate in the fermentation process is controlled according to a control algorithm corresponding to the determined fermentation period.

In different fermentation periods, the nutrients required by the cells are different, for example: During the lag phase, the cells need to adapt to the new environment, grow slowly, so less nutrients are needed; in the exponential growth phase, the cells enter the exponential division. At the stage, sufficient nutrient supply is required; during the stationary phase, the cell growth rate is approximately equal to the cell death rate, and the total cell number does not increase, so the nutrients consumed are also reduced. Due to the complexity and non-linearity of the fermentation process, it is not suitable to use a single control algorithm throughout the fermentation process.

In the embodiment of the present invention, different control algorithms are respectively adopted for different fermentation periods, so as to effectively control the nutrient feeding rate in the fermentation process. Specifically, the nutrient feed rate can be controlled by forward feedback or backward feedback control algorithms as follows:

Wherein // represents the specific growth rate calculated in step 102; / _i/7 represents a predetermined specific growth rate value (when the fermentation period is different, the specific value of the value will also be different); 0 represents the calculated specific growth a difference between the rate and the predetermined value of the specific growth rate; ^ and tunable parameters; Show nutrient feed rate; (0 indicates the forward feedback portion.

The specific calculation method of F _iQ (i) will also be different for different fermentation periods, for example - in the delay period, the calculation method is:

F _s0 (t) = k _{i +} k ₂ (t); (5) where , and is an adjustable parameter.

In the exponential growth phase, F _Q ( ) is calculated as:

F _s . ^) _spl X', (6) where, represents the cell density measurement, and A is a tunable parameter, indicating a predetermined growth rate for the exponential growth phase.

It can be seen that the value of _iQ ( ) will be adaptive in the stationary period according to the change of cell density measurement results, which is calculated as:

_{^ 0 (ί) ^ α +} βμ ψ3 (Χ-Χ ί2); (7) where, "a plateau represents the initial nutrient feed rate, equivalent to the nutrient feed rate at the end of the exponential growth phase, i.e., A ₂ , _2; is an adjustable parameter, ₃ represents a predetermined value of the specific growth rate of the stationary phase, represents a cell density measurement result, ₂ represents a start time of the stationary phase, and ₂ represents a cell density measurement result at ₂ o'clock. Again, you can see that. The value of () will be adaptively adjusted based on changes in cell density measurements.

It should be noted that the specific values of the threshold and the adjustable parameters and the like involved in the above embodiments may be determined according to actual needs. In addition, the solution of the present invention can be extended to control other aspects, such as dissolved oxygen.

Based on the above method, Fig. 6 is a schematic diagram showing the composition of the embodiment of the fermentation process controller of the present invention. As shown in Figure 6, it includes:

a fermentation period identification module 61, configured to determine a fermentation period currently in the fermentation process based on the obtained cell characteristic measurement result; The algorithm selection module 62 is configured to select a control algorithm corresponding to the determined fermentation period; and the control algorithm module 63 is configured to control the nutrient feeding rate in the fermentation process according to the selected control algorithm.

The fermentation period identification module 61 includes:

The data preprocessing sub-module 611 is configured to preprocess the obtained cell characteristic measurement result, identify the abnormal point and perform the culling;

The determining sub-module 612 is configured to determine whether the acquired cell characteristic measurement result includes only the cell density measurement result or both the cell density measurement result and the cell distribution measurement result, and notify the trend analysis and the fermentation period identification sub-module 613 of the determination result. ;

The trend analysis and fermentation period identification sub-module 613 is configured to determine the current fermentation period of the fermentation process by performing trend analysis on the cell density measurement result when the determination result includes only the cell density measurement result in the obtained cell characteristic measurement result. When the result of the determination is that the acquired cell characteristic measurement results include both the cell density measurement result and the cell distribution measurement result, the three-dimensional spatial tracking analysis of the cell density measurement result and the cell distribution measurement result is used to determine the fermentation currently in the fermentation process. period.

In addition, the fermentation process controller shown in FIG. 6 may further include:

The derivation model module 64 is configured to calculate the specific growth rate using the obtained cell density measurement result, / = - -, X represents the cell density measurement result, and the calculated specific growth rate is

X dt

Supply control algorithm module 63;

The control algorithm module 63 includes:

The first calculation sub-module 631 is configured to calculate a difference between the specific growth rate μ from the derivation model module 64 and a predetermined growth rate predetermined value Α _{自身 of the} pre-preserved according to the determined fermentation period, and the value will also be different;

A second calculation subunit 632 for calculating a nutrient feed rate as follows: F _s (t) = F _s0 (t) + K _c [e(t) + - [ t)dt]; (3) where ^ and ^ are tunable parameters; ) indicates the nutrient feed rate; (0 indicates the forward feedback portion;

When the determined fermentation period is a delay period, ( = +^(0; (5) where , and are tunable parameters;

When the determined fermentation period is the exponential growth phase, F ^k ^X', (6) where, represents the cell density measurement result, and A is an adjustable parameter, indicating a predetermined growth rate of the exponential growth phase;

When the determined fermentation period is a stationary period, _{() = Α + ^ 3 (} - ¾); (7) where, [alpha] represents a plateau of initial nutrient feed rate, adjustable parameters, ^ represents the growth rate than the predetermined value stationary phase, represents the cell density measurement , ^ indicates the start time of the stationary period, and ₂ indicates the cell density measurement at time ί ₂ .

The second calculation sub-unit 632 provides the calculated nutrient feed rate to the corresponding control unit in the fermentor to control the nutrient feed rate in the fermentor, thereby controlling the specific growth rate of the cells.

For the specific working process of the embodiment of the fermentation process controller shown in Fig. 6, please refer to the corresponding description in the embodiment of the method shown in Fig. 1, and details are not described herein again.

In summary, the present invention proposes an effective closed-loop feedback control scheme for nutrient feeding rate in a fermentation process, which can identify different fermentation periods and adopt different control algorithms for each fermentation period, thereby The nutrient feeding rate in different fermentation periods is always at an optimal value, and the accuracy of the feeding is ensured; moreover, the solution of the invention is simple to implement, convenient to popularize, and can be applied to various fermentation processes, such as Escherichia coli. , fermentation of yeast and animal cells, etc., and can significantly improve product quality and fermentation efficiency.

It should be noted that the foregoing embodiments are for illustrative purposes only and are not intended to limit the techniques of the present invention. Program. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Claim

A fermentation process control method, characterized in that the method comprises: determining a fermentation period currently in the fermentation process based on the obtained cell characteristic measurement result; and controlling the fermentation according to a control algorithm corresponding to the determined fermentation period The nutrient feed rate during the process is controlled.

2. The fermentation process control method according to claim 1, wherein the determining the fermentation period currently in the fermentation process based on the obtained cell characteristic measurement result comprises:

Determining whether the cell density measurement result and the cell distribution measurement result can be simultaneously obtained; if it can be simultaneously acquired, determining the current fermentation period of the fermentation process by performing three-dimensional spatial tracking analysis on the cell density measurement result and the cell distribution measurement result;

If only the cell density measurement results are obtained, the current fermentation period of the fermentation process is determined by performing a trend analysis on the cell density measurement results.

The fermentation process control method according to claim 2, wherein the determining the fermentation period currently in the fermentation process by performing trend analysis on the cell density measurement results includes:

Using the line equation, the cell density measurement results at each specified time point acquired after the A specified time points are checked, and the obtained cell density measurement results at each specified time point are calculated. Using the straight line equation to calculate a difference in cell density measurements at the specified time point, and comparing each difference with a predetermined limit level, if consecutive B differences are greater than the limit level , determining that the current fermentation period has been transferred from the delay period to the exponential growth period, and determining the time point corresponding to the first difference greater than the limit level as the inflection point;

Starting from the inflection point, fitting the cell density measurement results of the C consecutively obtained time points to an exponential curve, and obtaining a fitted exponential equation; Using the exponential equation, the cell density measurement results at each specified time point acquired after the c specified time points are verified, and the obtained cell density measurement results at each specified time point are calculated and Using the exponential equation to calculate a difference in cell density measurements at the specified time point, and comparing each difference to a predetermined limit level, if consecutive D differences are greater than the limit level , it is determined that the current fermentation period has been transferred from the exponential growth phase to the stationary phase; the A, B, C, and D are positive integers greater than one.

From the beginning of the fermentation process, the continuously obtained E group cell density measurement results are respectively fitted into a straight line; the E is a positive integer greater than 1; wherein, the cell density measurement results included in each group of cell density measurement results are included The same number;

And, each time the fitting of the set of cell density measurement results is completed, comparing the slope of the fitted straight line with a preset first threshold value, if the slope of the fitted straight line is greater than the first Threshold, determining that the current fermentation period has been transferred from the delay period to the exponential growth phase; thereafter, comparing the slope of the line fitted according to the next set of cell density measurements with a predetermined second threshold, if If the slope of the fitted straight line is less than the second threshold, it is determined that the current fermentation period has shifted from the exponential growth phase to the stationary phase.

The fermentation process control method according to claim 2, wherein the determining the fermentation period currently in the fermentation process by performing three-dimensional spatial tracking analysis on the cell density measurement result and the cell distribution measurement result comprises:

From the second specified time point, calculate the proportion of large cells at each specified time point and the ratio of cell density measurement to large cells at the previous specified time point and cell density measurement The difference between the quantity results, and comparing the calculated difference with a preset first combination threshold, if the consecutive F differences are greater than the first combination threshold, determining that the current fermentation period has been delayed The period is transferred to the exponential growth period, and the time point corresponding to the first difference larger than the first combination threshold is determined as an inflection point;

The fermentation process control method according to any one of claims 1 to 5, wherein the determining, based on the obtained cell characteristic measurement result, the fermentation period currently in the fermentation process, further comprises:

The obtained cell characteristic measurement result is preprocessed, and an abnormal point is identified and rejected.

The fermentation process control method according to any one of claims 1 to 5, wherein the feeding of nutrients in the fermentation process is performed according to a control algorithm corresponding to the determined fermentation period Rate control includes:

The nutrient feed rate was calculated as follows:

F _s (t) = F _s0 (t) + K _c [e(t) +丄]; the 6(0 = / - /^;

Wherein the i represents a specific growth rate calculated using the obtained cell density measurement result; the / represents a specific growth rate predetermined value; the indicating the calculated specific growth rate and the specific growth rate predetermined value The difference between ^; the /^ sum is an adjustable parameter; the (ί) represents the nutrient feed rate; the / ^. ( ) indicates the forward feedback portion, which is calculated using a control algorithm corresponding to the determined fermentation period.

8. The fermentation process control method according to claim 7, wherein the calculation method of the specific growth rate/includes:

= where the said is the cell density measurement.

X dt

9. The method according to claim 7, wherein the forward feedback portion ^. The calculation of (ί) includes:

When the determined fermentation period is a delay period, the said. ( = + ₂ (0; where the sum is an adjustable parameter;

When the determined fermentation period is an exponential growth phase, the / / ^ί) = ^ _ρ2; wherein the said cell density measurement result, the: is an adjustable parameter, the ratio indicates the growth rate of the exponential growth phase Predetermined value

When the determined fermentation period is a stationary period, the _Q (0=«+^ _p3 ( - ₂ ); wherein the α represents an initial nutrient feeding rate during the stationary period, the tunable parameter, ^ ₃ represents the growth rate of said predetermined value than a stable period, the cell indicates density measurement, the stationary phase represented ί ₂ starting time the ₂ _second time represents the cell density measurements.

10. A fermentation process controller, comprising:

a fermentation period identification module (61) for determining a fermentation period currently in the fermentation process based on the obtained cell characteristic measurement result;

An algorithm selection module (62) for selecting a control algorithm corresponding to the determined fermentation period; a control algorithm module (63) for controlling a nutrient feeding rate during the fermentation process according to the selected control algorithm .

11. The fermentation process controller of claim 10, wherein the fermentation period identification module (61) comprises:

a data pre-processing sub-module (611), configured to pre-process the obtained cell characteristic measurement result, identify the abnormal point and perform the culling;

Determining a sub-module (612) for determining that only the cells are included in the acquired cell characteristic measurement result The density measurement results also include the cell density measurement result and the cell distribution measurement result, and the determination result is notified to the trend analysis and fermentation period identification sub-module (613);

The trend analysis and fermentation period identification sub-module (613) is configured to determine the fermentation by performing trend analysis on the cell density measurement result when the determination result includes only the cell density measurement result in the obtained cell characteristic measurement result. The fermentation period currently in the process; when the determination result includes the cell density measurement result and the cell distribution measurement result in the obtained cell characteristic measurement result, the three-dimensional spatial tracking analysis is performed on the cell density measurement result and the cell distribution measurement result to determine The fermentation process is currently in the fermentation phase.

The fermentation process controller according to claim 10 or 11, wherein the fermentation process controller further comprises:

Deriving a model module (64) for calculating a specific growth rate using the obtained cell density measurement, μ = -^- , said the cell density measurement result, and calculating the calculated ratio

X at

Rate / is provided to the control algorithm module (63); the control algorithm module (63) includes:

a first calculation sub-module (631) for calculating a difference between a specific growth rate from the derivation model module (64) and a predetermined growth rate of the pre-preserved ratio according to the determined fermentation period, The value will also be different;

A second calculation subunit (632) for calculating the nutrient feed rate in the following manner:

F _s {t) =

+ K _c [e{t) + e{t)dt ; wherein the sum is an adjustable parameter; the F ί) represents a nutrient feeding rate; the indicating a forward feedback portion;

When the determined fermentation period is a delay period, the ^(0 = ^ + ^(0; wherein, the sum: ₂ is an adjustable parameter;

When the determined fermentation period is an exponential growth period, the said. (0 = ^^ _ρ2 ; where, The said cell density measurement result, wherein: the parameter is an adjustable parameter, and the ₂ represents a predetermined growth rate of the exponential growth phase;

When the determined fermentation period is a stationary period, the / ^ 0 = α + ^^^Γ-Α ₂ ) _; wherein the α represents an initial nutrient feeding rate during the stationary period, the To adjust the parameter, the _ίρ3 represents a predetermined value of the specific growth rate of the stationary phase, the indicating the cell density measurement result, the ₂ represents the start time of the stationary period, and the cell density measurement result indicating the _7th time.

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