Treatment method and system for fermentation of polymyxin sulfate
By analyzing historical fermentation data and pH mapping, the synthesis rate of polymyxin sulfate fermentation was adjusted, resolving the conflict between cell growth and product synthesis caused by its own toxicity, and ensuring the fermentation quality and the stability of product synthesis.
Patent Information
- Application Number
- CN202511094069.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-06
- Publication Date
- 2025-11-11
Smart Images
Figure CN120932774A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of bio-fermentation technology, specifically a method and system for polymyxin sulfate fermentation. Background Technology
[0002] The role of polymyxin sulfate fermentation is to efficiently synthesize polypeptide antibiotics with antibacterial activity through microbial metabolism. Its significance lies in meeting the clinical needs for treating drug-resistant bacterial infections, promoting the development of biopharmaceutical technology, ensuring public health security, and promoting the sustainable development of the antibiotic industry. In existing technologies, polymyxin sulfate fermentation has a unique characteristic of conflict between cell growth and product synthesis due to "autotoxicity." The antibacterial mechanism of polymyxin sulfate is through disrupting the cell membrane of Gram-negative bacteria (by binding to lipopolysaccharide). However, this effect may also have some toxicity to the cell membrane of the producing strain, *Bacillus polymyxin* (especially at high concentrations). In the later stages of fermentation, when polymyxin accumulates to a certain concentration in the fermentation broth, it inhibits normal cell metabolism (such as changes in cell membrane permeability and impaired nutrient absorption), leading to cell growth arrest or even autolysis. Premature termination of product synthesis is a significant issue. Furthermore, current technologies lack in-depth analysis of polymyxin sulfate fermentation concentration control, leading to additional negative fermentation effects. For instance, controlling the polymyxin sulfate synthesis rate via pH lacks a defined range, resulting in controlled synthesis rates while fatally impacting the activity of other substances. For example, excessively low pH can irreversibly alter the spatial structure of non-ribosomal peptide synthases (NRPS) under acidic conditions, drastically reducing (or even inactivating) their activity, causing near-total product synthesis cessation. Simultaneously, excessively low pH can disrupt cell membrane stability (e.g., affecting membrane protein function) and interfere with nutrient absorption (e.g., amino acids, phosphates), accelerating cell growth arrest or autolysis.
[0003] Therefore, the present invention provides a method and system for processing polymyxin sulfate fermentation, aiming to control the concentration of polymyxin sulfate during the fermentation process, avoid the problem of "autotoxicity", and efficiently ensure the fermentation quality. Summary of the Invention
[0004] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.
[0005] The technical solution adopted by this invention to solve its technical problem is: a method for treating polymyxin sulfate fermentation, comprising the following treatment steps: By analyzing historical fermentation data of polymyxin sulfate from multiple fermentations, the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation was determined. After the mid-stage fermentation of polymyxin sulfate begins, a preset monitoring period is established, and the product synthesis rate within the preset monitoring period is analyzed for stability to determine the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation. Based on the limited concentration of polymyxin sulfate in the middle and late stages of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, it is determined whether the product will exceed the limited concentration before the end of the fermentation cycle. If so, analyze the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation, and determine the minimum adjustable synthesis rate of the product based on the mapping relationship and the adjustable pH range. The adjustable time period for polymyxin sulfate fermentation in the middle and late stages, and the corresponding pH values at different adjustable time points within the adjustable time period, were determined based on the minimum adjustable synthesis rate.
[0006] A further technical solution is as follows: the process of determining the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation is as follows: By comparing the product termination times at different polymyxin concentrations in historical fermentation data, the early termination concentrations were obtained and summarized into a set of early termination concentrations. The volatility of the early termination concentration set is determined by the coefficient of variation method. If the volatility is high, the minimum polymyxin concentration in the early termination concentration set is taken as the limit concentration of polymyxin sulfate in the middle and late stages of fermentation. If the volatility is low, the early termination concentration set is averaged to obtain the limit concentration of polymyxin sulfate in the middle and late stages of fermentation.
[0007] A further technical solution is as follows: the process of performing stability analysis on the product synthesis rate within the preset monitoring period is as follows: The product synthesis rate at different monitoring time points within a preset monitoring period is obtained, and the product synthesis rate sequence is obtained by summarizing the results according to the time sequence. Calculate the coefficient of variation of the product synthesis rate sequence; If the coefficient of variation of the product synthesis rate sequence is greater than or equal to the coefficient of variation threshold, it indicates that the product synthesis rate is unstable within the preset monitoring period; otherwise, it indicates that the product synthesis rate is stable within the preset monitoring period.
[0008] The further technical solution is as follows: The process for determining the predicted synthesis rate of polymyxin sulfate in the mid-to-late stages of fermentation is as follows: If the product synthesis rate is unstable during the preset monitoring period, the maximum synthesis rate in the product synthesis rate sequence is selected as the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation. If the product synthesis rate is stable within the preset monitoring period, the product synthesis rate sequence is averaged, and the average synthesis rate of the product synthesis rate sequence is used as the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation.
[0009] A further technical solution is as follows: the process of determining whether the product will exceed the limit concentration before the end of the fermentation cycle is as follows: Calculate the absolute concentration deviation between the product concentration at the end of the preset monitoring period and the limit concentration of polymyxin sulfate in the middle and late fermentation stages; The ratio between the absolute concentration deviation and the predicted synthesis rate of polymyxin sulfate is calculated to obtain the time it takes for the product concentration to reach the limit concentration. Combined with the end time of the preset monitoring period, the summation is used to determine the time point when the concentration reaches the limit. If the concentration reaches the critical point before the end of the fermentation cycle, it indicates that it will exceed the limit. If the concentration reaches the limit at the same time as the end of the fermentation cycle, or if the concentration reaches the limit after the end of the fermentation cycle, it means that the concentration will not be exceeded.
[0010] A further technical solution is as follows: The process of analyzing the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation is as follows: The product synthesis rate of polymyxin sulfate under different pH fermentation conditions was obtained, and the different pH values were summarized into a pH value sequence, and the product synthesis rate under different pH fermentation conditions was summarized into a product synthesis rate sequence. The Pearson correlation coefficient between the pH value sequence and the product synthesis rate sequence was calculated using the Pearson correlation coefficient method. If the Pearson correlation coefficient is within the preset range, it indicates that there is a linear mapping relationship between pH value and product synthesis rate; otherwise, it indicates that there is a non-linear mapping relationship between pH value and product synthesis rate.
[0011] A further technical solution is as follows: the process of determining the minimum tunable synthesis rate of the product is as follows: If a linear mapping relationship exists, the least squares method is used to fit the product synthesis rate sequence to obtain a fitting model; If the slope coefficient of the fitted model is less than 0, then the maximum endpoint value of the pH adjustable range is substituted into the fitted model to obtain the minimum adjustable synthesis rate. If the slope coefficient of the fitted model is greater than 0, then the minimum endpoint value of the pH adjustable range is substituted into the fitted model to obtain the minimum adjustable synthesis rate. If a nonlinear mapping relationship exists, the pH value and the corresponding product synthesis rate are aggregated to obtain a training data set. Multiple training data sets are used to train the neural network model to obtain a mapping model between pH value and product synthesis rate. By substituting different pH values within the adjustable pH range into the mapping model, the minimum output value is selected as the minimum adjustable synthesis rate.
[0012] A further technical solution is as follows: the process of determining the adjustable specified time period for polymyxin sulfate fermentation in the middle and late stages is as follows: The product concentration at the end of the preset monitoring period was obtained, and the predicted product concentration at different time points after the preset monitoring period was calculated based on the predicted synthesis rate of polymyxin sulfate in the middle and late fermentation. The difference between the predicted product concentration and the specified concentration of polymyxin sulfate in the middle and late stages of fermentation is calculated to obtain the predicted concentration difference. The time point at which the predicted concentration difference is calculated is marked as the calculation time point. The duration deviation between the calculation time point and the end time of the polymyxin sulfate fermentation cycle is calculated. The ratio of the predicted concentration difference to the duration deviation is calculated to obtain the required synthesis rate. If the required synthesis rate is greater than or equal to the minimum synthesis rate, then the current calculation time point is marked as an adjustable time point; Conversely, the current calculation time point is marked as an unadjustable time point; The system iterates through the time points after the preset monitoring period until it reaches an uncontrollable time point, at which point the iteration stops. The time period formed by the controllable time points that have been iterated through is the adjustable specified time period.
[0013] A further technical solution is as follows: The method for determining the pH value corresponding to different adjustable time points within the adjustable specified time period is as follows: If there is a linear mapping relationship between pH value and product synthesis rate, then the required synthesis rate at the adjustable time point is substituted into the fitting model to obtain the pH value corresponding to the adjustable time point. If there is a nonlinear mapping relationship between pH value and product synthesis rate, the required synthesis rate at the adjustable time point is substituted into the mapping model to obtain the pH value corresponding to the adjustable time point.
[0014] A polymyxin sulfate fermentation treatment system includes the following processing modules: Fermentation Limitation Analysis Module: Analyze and determine the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation by analyzing historical fermentation data of polymyxin sulfate multiple times; Synthesis prediction and analysis module: After the mid-stage fermentation of polymyxin sulfate begins, a preset monitoring period is set, and the stability analysis of the product synthesis rate within the preset monitoring period is performed to determine the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation. Fermentation Exceedance Judgment Module: Based on the limited concentration of polymyxin sulfate in the middle and late stages of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, determine whether the product will exceed the limited concentration before the end of the fermentation cycle. Adjustable rate analysis module: If you are able to do this, analyze the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation, and determine the minimum adjustable synthesis rate of the product based on the mapping relationship and the adjustable pH range. Synthesis Adjustment Determination Module: Based on the minimum adjustable synthesis rate, determine the adjustable time period for polymyxin sulfate fermentation in the middle and late stages, as well as the pH value corresponding to different adjustable time points within the adjustable time period.
[0015] The beneficial effects of this invention are as follows: By analyzing historical fermentation data of polymyxin sulfate multiple times, the limited concentration of polymyxin sulfate in the mid-to-late stage of fermentation is determined. After the start of mid-stage fermentation of polymyxin sulfate, a preset monitoring period is established, and the stability analysis of the product synthesis rate within the preset monitoring period is performed to determine the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation. Based on the limited concentration of polymyxin sulfate in the mid-to-late stage of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, it is determined whether the product will exceed the limited concentration before the end of the fermentation cycle. If so, the mapping relationship between the pH value during polymyxin sulfate fermentation and the product synthesis rate is analyzed. Based on the mapping relationship and combined with the adjustable pH range, the minimum adjustable synthesis rate of the product is determined. The minimum adjustable synthesis rate determines the adjustable time period for polymyxin sulfate fermentation in the middle and late stages, as well as the corresponding pH values at different adjustable time points within the adjustable time period. This invention determines the limited concentration for polymyxin sulfate fermentation using historical fermentation data. Based on this, the subsequent fermentation synthesis rate is predicted by monitoring the product synthesis rate within a preset time period. It also determines whether the product concentration will exceed the limit during the fermentation cycle, thus affecting fermentation due to its own toxicity. If the concentration exceeds the limit, the adjustment limit of the synthesis rate is determined according to the adjustable allowable range of pH value. Based on the adjustment limit, the allowable control period for synthesis and the pH at different adjustable time points are determined. This is beneficial because adjusting the synthesis rate will not lead to other fermentation effects caused by pH exceeding the limit, thus ensuring the fermentation quality of polymyxin sulfate. Attached Figure Description
[0016] The invention will now be further described with reference to the accompanying drawings.
[0017] Figure 1 This is a flowchart of the steps of a polymyxin sulfate fermentation treatment method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the logic judgment of a polymyxin sulfate fermentation treatment method according to an embodiment of the present invention; Figure 3 This is a flowchart of a polymyxin sulfate fermentation treatment system according to an embodiment of the present invention. Detailed Implementation
[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.
[0019] Example 1: Please refer to Figures 1-2 As shown in the embodiment of the present invention, a method for treating polymyxin sulfate fermentation includes: Step 1: Analyze and determine the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation by analyzing historical fermentation data of polymyxin sulfate multiple times; In step one, the historical fermentation data of polymyxin sulfate includes the termination time of the product (polymyxin B) at different polymyxin concentrations. In step one, the process of determining the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation is as follows: Obtain the product termination time (product synthesis termination time) at different polymyxin concentrations and compare it with the preset product termination time. If the product termination time is before the preset product termination time, and the time difference between the product termination time and the preset product termination time is greater than the preset time difference, then the polymyxin concentration corresponding to the product termination time is marked as the early termination concentration. Conversely, no action is taken; The early termination concentrations of all marked early termination concentrations are aggregated to obtain the early termination concentration set. The coefficient of variation of the premature termination concentration set is obtained by calculating the coefficient of variation of the premature termination concentration set using the coefficient of variation method. The coefficient of variation is the ratio of the standard deviation to the mean of the early termination concentration set. If the coefficient of variation of the early termination concentration set is less than the coefficient of variation threshold, the early termination concentration set is averaged and the average concentration of the early termination concentration set is used as the limit concentration of polymyxin sulfate in the middle and late stages of fermentation. If the coefficient of variation of the early termination concentration set is greater than or equal to the coefficient of variation threshold, then the minimum value of the early termination concentration set is selected, and the minimum polymyxin concentration in the early termination concentration set is used as the limit concentration of polymyxin sulfate in the middle and late stages of fermentation. Understandably, if the coefficient of variation is less than the coefficient of variation threshold, it indicates that the dispersion of polymyxin concentration in the early termination concentration group is small, and the polymyxin concentration deviation that leads to early termination of the product is small. Therefore, averaging is performed, and the average concentration is used as the limit concentration. Conversely, if the coefficient of variation is greater than or equal to the coefficient of variation threshold, it indicates that the dispersion of polymyxin concentration in the early termination concentration group is large, and the polymyxin concentration deviation that leads to early termination of the product is large. In order to ensure the fermentation quality of polymyxin sulfate, the minimum concentration is selected as the limit concentration. The polymyxin sulfate fermentation process described in the embodiments of the present invention can be as follows: A highly efficient polymyxin B-producing strain (such as Bacillus polymyxa) is used. The strain is preserved under aseptic conditions at low temperatures (e.g., -80°C or liquid nitrogen) through slant culture or glycerol tubes. The preserved strain is inoculated onto fresh solid slant culture medium and cultured at a suitable temperature (usually 28-32°C) for a certain time (e.g., 24-48 hours) to restore its activity. Colonies are picked from the activated slant and inoculated into shake flasks containing liquid seed culture medium. The culture is then carried out on a shaker, with controlled temperature (28-32°C), rotation speed, and culture time (e.g., 18-24 hours) to obtain a seed culture. The seed culture from the shake flask is transferred to a larger seed tank at a certain inoculation rate (usually 5%-15%). The seed tank contains sterilized seed culture medium, sterile air is introduced, and the temperature (28-32°C) and stirring are controlled. Rotation speed, tank pressure (maintaining positive pressure), pH (usually natural or finely adjusted), and dissolved oxygen level (DO) are controlled. The cells are cultured until they are in the late logarithmic growth stage (usually 12-24 hours). The seed culture in optimal growth condition is inoculated into the fermenter at a certain ratio (usually 5%-15%). The temperature is usually maintained at 28-32°C. A large amount of sterile compressed air is introduced and thoroughly mixed by stirring paddles to maintain a high level of dissolved oxygen (DO). A certain positive pressure (e.g., 0.03-0.05 MPa) is maintained to prevent contamination. The pH is controlled by adding acid (e.g., H2SO4) or alkali (e.g., NaOH, ammonia), and is often controlled within a certain range (e.g., 6.0-7.0). After fermentation, acidification heating and cooling pretreatment are performed. After pretreatment, solid-liquid separation and extraction are performed to obtain polymyxin sulfate product. Step 2: After the mid-stage fermentation of polymyxin sulfate begins, a preset monitoring period is established, and the product synthesis rate within the preset monitoring period is subjected to stability analysis. Based on the stability analysis results, the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation is determined. In step two, the process of performing stability analysis on the product synthesis rate within the preset monitoring period is as follows: The product synthesis rate at different monitoring time points within a preset monitoring period is obtained, and the product synthesis rate sequence is obtained by summarizing the results according to the time sequence. Among them, the preset monitoring period is shorter than the polymyxin sulfate fermentation cycle; Calculate the coefficient of variation of the product synthesis rate sequence, where the coefficient of variation is the ratio of the standard deviation to the mean of the product synthesis rate sequence. If the coefficient of variation of the product synthesis rate sequence is greater than or equal to the coefficient of variation threshold, it indicates that the product synthesis rate is unstable within the preset monitoring period. If the coefficient of variation of the product synthesis rate sequence is less than the coefficient of variation threshold, it indicates that the product synthesis rate is stable within the preset monitoring period. In step two, the process of determining the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation based on the stability analysis results is as follows: If the product synthesis rate is unstable during the preset monitoring period, the maximum synthesis rate in the product synthesis rate sequence is selected as the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation. If the product synthesis rate is stable within the preset monitoring period, the product synthesis rate sequence is averaged and the average synthesis rate of the product synthesis rate sequence is used as the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation. It is understandable that if the product synthesis rate is unstable during the preset monitoring period, the maximum synthesis rate in the product synthesis rate sequence is selected as the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation. The reason for selecting the maximum synthesis rate as the predicted synthesis rate in the middle and late stages is to ensure that the product concentration can be effectively controlled under harsh conditions and not exceed the toxicity threshold, thereby avoiding premature termination of fermentation. Step 3: Based on the limited concentration of polymyxin sulfate in the middle and late stages of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, determine whether the product will exceed the limited concentration before the end of the fermentation cycle. In step three, the process of determining whether the product concentration will exceed the limit before the end of the fermentation cycle is as follows: The limit concentration of polymyxin sulfate in the mid-to-late stage of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period were obtained. The absolute concentration deviation between the product concentration at the end of the preset monitoring period and the limit concentration of polymyxin sulfate in the mid-to-late stage of fermentation was calculated. The ratio between the absolute concentration deviation and the predicted synthesis rate of polymyxin sulfate is calculated to obtain the time required for the product concentration to reach the specified concentration. By combining the end time of the preset monitoring period and the duration of time it takes for the product concentration to reach the limit concentration, the time point at which the product concentration reaches the limit concentration is determined, i.e., the concentration threshold time point (end time of the preset monitoring period + duration of time for the product to reach the limit concentration). Compare the time point when the concentration reaches the critical point with the time point at the end of the fermentation cycle; If the concentration reaches the limit point before the end of the fermentation cycle, it means that the product will exceed the limit concentration before the end of the fermentation cycle. If the concentration reaches the limit at the same time as the end of the fermentation cycle, or if the concentration reaches the limit at a time after the end of the fermentation cycle, it means that the product will not exceed the limit concentration before the end of the fermentation cycle. Step 4: If you know how, analyze the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation, and determine the minimum adjustable synthesis rate of the product based on the mapping relationship and the adjustable pH range. In step four, the process of analyzing the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation is as follows: The product synthesis rate of polymyxin sulfate under different pH fermentation conditions was obtained, and the different pH values were summarized into a pH value sequence, and the product synthesis rate under different pH fermentation conditions was summarized into a product synthesis rate sequence. It should be noted that each pH value corresponds to a product synthesis rate, and the pH value and the corresponding product synthesis rate are in the same position in the sequence. The Pearson correlation coefficient between the pH value sequence and the product synthesis rate sequence was calculated using the Pearson correlation coefficient method. If the Pearson correlation coefficient is within the preset range, it indicates that there is a linear mapping relationship between pH value and product synthesis rate; If the Pearson correlation coefficient is not within the preset range, it indicates that there is a non-linear mapping relationship between pH value and product synthesis rate; In step four, the process of determining the minimum adjustable synthesis rate of the product based on the mapping relationship and the adjustable pH range is as follows: If there is a linear mapping relationship between pH value and product synthesis rate, the product synthesis rate sequence is fitted using the least squares method to obtain the fitting model: y=kx+b, where y represents the product synthesis rate, k represents the slope coefficient, x represents pH, and b represents the intercept. If the slope coefficient of the fitted model is less than 0, then the maximum endpoint value of the pH adjustable range is substituted into the fitted model to obtain the minimum adjustable synthesis rate. If the slope coefficient of the fitted model is greater than 0, then the minimum endpoint value of the pH adjustable range is substituted into the fitted model to obtain the minimum adjustable synthesis rate. If there is a non-linear mapping relationship between pH value and product synthesis rate, then the pH value and the corresponding product synthesis rate are aggregated to obtain a training data set. Since different pH values correspond to different product synthesis rates, multiple training data sets are obtained. The neural network model (LSTM model) was trained using multiple sets of training data to obtain a mapping model between pH value and product synthesis rate; Based on the adjustable pH range, different pH values within the adjustable pH range are substituted into the mapping model to obtain multiple product synthesis rates. The minimum value is selected as the minimum adjustable synthesis rate. It should be noted that the adjustable pH range is set according to the requirements of polymyxin sulfate fermentation. For example, the pH is set to [6.4-6.7] when polymyxin sulfate fermentation is carried out in the normal middle and late stages. It should also be noted that the purpose of determining the minimum tunable synthesis rate is: Determining the minimum adjustable synthesis rate clarifies the limit of the product synthesis rate regulation when product concentration control is required during polymyxin sulfate fermentation, which is beneficial for subsequently determining the regulation strategy (the allowable regulation time period and the pH value at different regulation time points). Determining the minimum adjustable synthesis rate is beneficial in subsequent regulation to prevent the normal fermentation pH range from being ignored in order to control the concentration of the product during polymyxin sulfate fermentation, which could lead to other fermentation problems and ensure that the fermentation reaction proceeds normally while controlling the concentration. It should be noted that the minimum adjustable synthesis rate represents the minimum synthesis rate that can be achieved by reducing the product synthesis rate within the pH adjustment range. Step 5: Determine the adjustable time period for polymyxin sulfate fermentation in the middle and late stages, and the corresponding pH values at different adjustable time points within the adjustable time period, based on the minimum adjustable synthesis rate. In step five, the process of determining the adjustable time period for polymyxin sulfate fermentation in the middle and late stages is as follows: The product concentration at the end of the preset monitoring period was obtained, and the predicted product concentration at different time points after the preset monitoring period was calculated based on the predicted synthesis rate of polymyxin sulfate in the middle and late fermentation. The predicted product concentration is calculated as follows: product concentration at the end of the preset monitoring period + [predicted synthesis rate * (calculation time point - end of preset monitoring period)], where the calculation time point is the time point at which the predicted product concentration needs to be calculated. The difference between the predicted product concentration and the specified concentration of polymyxin sulfate in the middle and late stages of fermentation is calculated to obtain the predicted concentration difference. The time point at which the predicted concentration difference is calculated is marked as the calculation time point. The duration deviation between the calculation time point and the end time of the polymyxin sulfate fermentation cycle is calculated. The ratio of the predicted concentration difference to the duration deviation is calculated to obtain the required synthesis rate. The required synthesis rate represents the product synthesis rate required to achieve the desired product concentration at the calculated time point when the product concentration is adjusted. Compare the desired synthesis rate with the minimum synthesis rate; If the required synthesis rate is greater than or equal to the minimum synthesis rate, it means that adjusting the product synthesis rate at the current calculation time point can control the product concentration within the specified range at the end of the fermentation cycle. In this case, the current calculation time point is marked as an adjustable time point. If the required synthesis rate is less than the minimum synthesis rate, it means that if the product synthesis rate is adjusted at the current calculation time point, it is impossible to control the product concentration within the limited concentration range at the end of the fermentation cycle within the limit of the synthesis rate adjustment capability. In this case, the current calculation time point is marked as an unadjustable time point. The time points after the preset monitoring period are traversed until an uncontrollable time point is reached, at which point the traversal stops. The time period formed by the controllable time points that have been traversed is the adjustable specified time period. For example, the predicted monitoring period technical time point is T0, and the subsequent time points are T1, T2, T3...Tn, where Tn is the end time point of the fermentation cycle. If T1, T2, and T3 are adjustable time points and T4 is an unadjustable time point, then the traversal stops, and the adjustable specified period is (T1-T3). It should be noted that the adjustable specified time period means that the product synthesis rate can be controlled within the adjustable specified time period to meet the product concentration control requirements. However, if the control is performed beyond the adjustable specified time period, the product concentration control requirements cannot be met according to the control limit capability. In step five, the method for determining the pH value corresponding to different adjustable time points within the adjustable specified time period is as follows: If there is a linear mapping relationship between pH value and product synthesis rate, then the required synthesis rate at the adjustable time point is substituted into the fitting model to obtain the pH value corresponding to the adjustable time point. If there is a nonlinear mapping relationship between pH value and product synthesis rate, the required synthesis rate at the adjustable time point is substituted into the mapping model to obtain the pH value corresponding to the adjustable time point. The pH value at the adjustable time point means that if the synthesis rate is controlled at the adjustable time point, the pH value is adjusted to the corresponding value, and the pH value is dynamically maintained to a stable value during subsequent fermentation until the end of the fermentation cycle. The technical solution of this invention is as follows: By analyzing historical fermentation data of polymyxin sulfate multiple times, the limited concentration of polymyxin sulfate in the mid-to-late stage of fermentation is determined. After the start of mid-stage fermentation of polymyxin sulfate, a preset monitoring period is established, and the stability analysis of the product synthesis rate within the preset monitoring period is performed to determine the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation. Based on the limited concentration of polymyxin sulfate in the mid-to-late stage of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, it is determined whether the product will exceed the limited concentration before the end of the fermentation cycle. If so, the mapping relationship between the pH value during polymyxin sulfate fermentation and the product synthesis rate is analyzed. Based on the mapping relationship and combined with the adjustable pH range, the minimum adjustable synthesis rate of the product is determined. This invention determines the adjustable time period for polymyxin sulfate fermentation in the mid-to-late stages based on the minimum adjustable synthesis rate, as well as the corresponding pH values at different adjustable time points within the adjustable time period. It uses historical fermentation data to determine the limiting concentration for polymyxin sulfate fermentation. Based on this, it predicts the subsequent fermentation synthesis rate by monitoring the product synthesis rate within a preset time period and assesses whether the product concentration will exceed the limit during the fermentation cycle, thus affecting fermentation due to its own toxicity. If the concentration exceeds the limit, it determines the adjustment limit of the synthesis rate based on the adjustable allowable pH range, and then determines the allowable control period for synthesis and the pH at different adjustable time points based on the adjustment limit. This ensures that adjusting the synthesis rate does not lead to other fermentation effects caused by pH exceeding the limit, guaranteeing the quality of polymyxin sulfate fermentation.
[0020] Example 2: Please refer to Figure 3 As shown in the embodiment of the present invention, a polymyxin sulfate fermentation treatment system includes: Fermentation Limitation Analysis Module: Analyze and determine the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation by analyzing historical fermentation data of polymyxin sulfate multiple times; Synthesis prediction and analysis module: After the mid-stage fermentation of polymyxin sulfate begins, a preset monitoring period is set, and the stability analysis of the product synthesis rate within the preset monitoring period is performed to determine the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation. Fermentation Exceedance Judgment Module: Based on the limited concentration of polymyxin sulfate in the middle and late stages of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, determine whether the product will exceed the limited concentration before the end of the fermentation cycle. Adjustable rate analysis module: If you are able to do this, analyze the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation, and determine the minimum adjustable synthesis rate of the product based on the mapping relationship and the adjustable pH range. Synthesis Adjustment Determination Module: Based on the minimum adjustable synthesis rate, determine the adjustable time period for polymyxin sulfate fermentation in the middle and late stages, as well as the pH value corresponding to different adjustable time points within the adjustable time period.
[0021] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for treating polymyxin sulfate through fermentation, characterized in that: The following processing steps are included: By analyzing historical fermentation data of polymyxin sulfate from multiple fermentations, the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation was determined. After the mid-stage fermentation of polymyxin sulfate begins, a preset monitoring period is established, and the product synthesis rate within the preset monitoring period is analyzed for stability to determine the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation. Based on the limited concentration of polymyxin sulfate in the middle and late stages of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, it is determined whether the product will exceed the limited concentration before the end of the fermentation cycle. If so, analyze the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation, and determine the minimum adjustable synthesis rate of the product based on the mapping relationship and the adjustable pH range. The adjustable time period for polymyxin sulfate fermentation in the middle and late stages, and the corresponding pH values at different adjustable time points within the adjustable time period, were determined based on the minimum adjustable synthesis rate.
2. The method for treating polymyxin sulfate fermentation according to claim 1, characterized in that: The process for determining the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation is as follows: By comparing the product termination times at different polymyxin concentrations in historical fermentation data, the early termination concentrations were obtained and summarized into a set of early termination concentrations. The volatility of the early termination concentration set is determined by the coefficient of variation method. If the volatility is high, the minimum polymyxin concentration in the early termination concentration set is taken as the limit concentration of polymyxin sulfate in the middle and late stages of fermentation. If the volatility is low, the early termination concentration set is averaged to obtain the limit concentration of polymyxin sulfate in the middle and late stages of fermentation.
3. The method for treating polymyxin sulfate fermentation according to claim 1, characterized in that: The process of performing stability analysis on the product synthesis rate within the preset monitoring period is as follows: The product synthesis rate at different monitoring time points within a preset monitoring period is obtained, and the product synthesis rate sequence is obtained by summarizing the results according to the time sequence. Calculate the coefficient of variation of the product synthesis rate sequence; If the coefficient of variation of the product synthesis rate sequence is greater than or equal to the coefficient of variation threshold, it indicates that the product synthesis rate is unstable within the preset monitoring period; otherwise, it indicates that the product synthesis rate is stable within the preset monitoring period.
4. The method for treating polymyxin sulfate fermentation according to claim 3, characterized in that: The process for determining the predicted synthesis rate of polymyxin sulfate in the mid-to-late stages of fermentation is as follows: If the product synthesis rate is unstable during the preset monitoring period, the maximum synthesis rate in the product synthesis rate sequence is selected as the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation. If the product synthesis rate is stable within the preset monitoring period, the product synthesis rate sequence is averaged, and the average synthesis rate of the product synthesis rate sequence is used as the predicted synthesis rate of polymyxin sulfate in the middle and late stages of fermentation.
5. The method for treating polymyxin sulfate fermentation according to claim 4, characterized in that: The process for determining whether the product concentration will exceed the limit before the end of the fermentation cycle is as follows: Calculate the absolute concentration deviation between the product concentration at the end of the preset monitoring period and the limit concentration of polymyxin sulfate in the middle and late fermentation stages; The ratio between the absolute concentration deviation and the predicted synthesis rate of polymyxin sulfate is calculated to obtain the time it takes for the product concentration to reach the limit concentration. Combined with the end time of the preset monitoring period, the summation is used to determine the time point when the concentration reaches the limit. If the concentration reaches the critical point before the end of the fermentation cycle, it indicates that it will exceed the limit. If the concentration reaches the limit at the same time as the end of the fermentation cycle, or if the concentration reaches the limit after the end of the fermentation cycle, it means that the concentration will not be exceeded.
6. The method for treating polymyxin sulfate fermentation according to claim 5, characterized in that: The process of analyzing the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation is as follows: The product synthesis rate of polymyxin sulfate under different pH fermentation conditions was obtained, and the different pH values were summarized into a pH value sequence, and the product synthesis rate under different pH fermentation conditions was summarized into a product synthesis rate sequence. The Pearson correlation coefficient between the pH value sequence and the product synthesis rate sequence was calculated using the Pearson correlation coefficient method. If the Pearson correlation coefficient is within the preset range, it indicates that there is a linear mapping relationship between pH value and product synthesis rate; otherwise, it indicates that there is a non-linear mapping relationship between pH value and product synthesis rate.
7. The method for treating polymyxin sulfate fermentation according to claim 6, characterized in that: The process of determining the minimum tunable synthesis rate of the product is as follows: If a linear mapping relationship exists, the least squares method is used to fit the product synthesis rate sequence to obtain a fitting model; If the slope coefficient of the fitted model is less than 0, then the maximum endpoint value of the pH adjustable range is substituted into the fitted model to obtain the minimum adjustable synthesis rate. If the slope coefficient of the fitted model is greater than 0, then the minimum endpoint value of the pH adjustable range is substituted into the fitted model to obtain the minimum adjustable synthesis rate. If a nonlinear mapping relationship exists, the pH value and the corresponding product synthesis rate are aggregated to obtain a training data set. Multiple training data sets are used to train the neural network model to obtain a mapping model between pH value and product synthesis rate. By substituting different pH values within the adjustable pH range into the mapping model, the minimum output value is selected as the minimum adjustable synthesis rate.
8. The method for treating polymyxin sulfate fermentation according to claim 7, characterized in that: The process for determining the adjustable time period for polymyxin sulfate fermentation in the middle and late stages is as follows: The product concentration at the end of the preset monitoring period was obtained, and the predicted product concentration at different time points after the preset monitoring period was calculated based on the predicted synthesis rate of polymyxin sulfate in the middle and late fermentation. The difference between the predicted product concentration and the specified concentration of polymyxin sulfate in the middle and late stages of fermentation is calculated to obtain the predicted concentration difference. The time point at which the predicted concentration difference is calculated is marked as the calculation time point. The duration deviation between the calculation time point and the end time of the polymyxin sulfate fermentation cycle is calculated. The ratio of the predicted concentration difference to the duration deviation is calculated to obtain the required synthesis rate. If the required synthesis rate is greater than or equal to the minimum synthesis rate, then the current calculation time point is marked as an adjustable time point; Conversely, the current calculation time point is marked as an unadjustable time point; The system iterates through the time points after the preset monitoring period until it reaches an uncontrollable time point, at which point the iteration stops. The time period formed by the controllable time points that have been iterated through is the adjustable specified time period.
9. The method for treating polymyxin sulfate fermentation according to claim 8, characterized in that: The method for determining the pH value corresponding to different adjustable time points within the adjustable specified time period is as follows: If there is a linear mapping relationship between pH value and product synthesis rate, then the required synthesis rate at the adjustable time point is substituted into the fitting model to obtain the pH value corresponding to the adjustable time point. If there is a non-linear mapping relationship between pH value and product synthesis rate, then the required synthesis rate at the adjustable time point is substituted into the mapping model to obtain the pH value corresponding to the adjustable time point.
10. A treatment system for polymyxin sulfate fermentation, characterized in that: Includes the following processing modules: Fermentation Limitation Analysis Module: Analyze and determine the limiting concentration of polymyxin sulfate in the middle and late stages of fermentation by analyzing historical fermentation data of polymyxin sulfate multiple times; Synthesis prediction and analysis module: After the mid-stage fermentation of polymyxin sulfate begins, a preset monitoring period is set, and the stability analysis of the product synthesis rate within the preset monitoring period is performed to determine the predicted synthesis rate of polymyxin sulfate in the mid-to-late stage of fermentation. Fermentation Exceedance Judgment Module: Based on the limited concentration of polymyxin sulfate in the middle and late stages of fermentation, the predicted synthesis rate of polymyxin sulfate, and the product concentration at the end of the preset monitoring period, determine whether the product will exceed the limited concentration before the end of the fermentation cycle. Adjustable rate analysis module: If you are able to do this, analyze the mapping relationship between pH value and product synthesis rate during polymyxin sulfate fermentation, and determine the minimum adjustable synthesis rate of the product based on the mapping relationship and the adjustable pH range. Synthesis Adjustment Determination Module: Based on the minimum adjustable synthesis rate, determine the adjustable time period for polymyxin sulfate fermentation in the middle and late stages, as well as the pH value corresponding to different adjustable time points within the adjustable time period.