Team:OUC-China
Strain cells are placed in fermenters for proliferation and fermentation. And the time is set to the constant time of strain fermentation based on the best time measured by the comprehensive experiment (i. e., a significant decrease in product secretion is detected and maintained at a certain threshold, when the productive strain has been killed). After that, strains are allowed to proliferate for 2 hours and reciprocate like this. The products are also isolated, purified and collected. Open the microvalve controller and transfer the metabolism of strains to the expansion bed for adsorption. Here, the CroCD-TuC series, a total of seven kinds, can be screened for the most appropriate according to the target products (but due to the epidemic reasons and limited funds, hardware is not a complete experiment, only a preliminary design, finally choosing the best fluid dynamic state of CroCD-TuC3 according to the fluid dynamic state).
In the design, the main material selected is cyclodextrin polymer, but although the cavity of cyclodextrin can form a wrapping complex with a variety of organic compounds, the wrapping ability is not very strong for most molecules. Therefore, affinity ligands can be designed according to the target products, through high-throughput screening of the compound library, combined with computational chemical and molecular simulation methods, and the most appropriate ligands on the edge modification of cyclodextrin based on the calculated ligand and receptor interaction energy, thus enhancing the adsorption capacity of the product (the project is to design a platform, can be applied to a variety of different products, so have different substrate design and selection for different products). In the late adsorption period, the density of the matrix particles increases due to the adsorption of target products and some impurities, thus to maintain the original expansion rate to ensure that the expansion bed can be used for a long time (E=2.5 is best). So an infrared sensor is installed on the top of the expansion bed to obtain the expansion rate E by monitoring the distance from the top to the adsorbent, and then transmit the signal to the calculation processor. The calculation processor calculates the current B0 according to the received E value, and automatically compares the value of B0 and Arabic Number 40. When B0> 40 can be considered approximately flat push through. However, if B0<40, we need to get the due E value and get the flow rate U value (see below for specific formula). The signal is transmitted to the microvalve regulator to automatically adjust the outflow rate of our strains’ metabolites. When the strains perform the next round of value-added fermentation, the products obtained from the previous round of fermentation can be eluted from the expansion bed.
And the hardware of this design is a constant culture fermentation device. In a small proliferative fermentation cycle, strains’concentration increases to a peak through proliferation. At this time, the products produced by fermentation have a higher concentration. In order to prevent the RNA aptamer from transporting the product back to strains’cells, the fermentation liquid is fast. Afterwards, the concentration of the strains decreases slightly because the less productive strains are killed, which means the concentration of products in the fermenters declines and the probability of the RNA aptamer shipping the product back inside the cell decreases. Meanwhile, it may be B0 <40, so at this time the microvalve regulator receives the control signal of the calculation processor to slow down the flow rate. Thus, the constant chemical culture is realized. (In a small proliferative fermentation cycle, the concentration of strains is actually in a stable period.)
The specific formula is as follows:
If we only consider the role of the viscosity force in the relative motion of the particle and the fluid, we can adopt the Stokes formula.
In the above formula, U is the linear flow rate and ε is the bed gap rate, and the relationship between U and ε indicates the expansion characteristics of the bed in the expansion bed. n is the expansion index. Utis the terminal settlement rate of particles. Ut,Sto the particle terminal settlement rate calculated using the Stokes formula. ρp and ρl the density of adsorbent particles and fluid, respectively. g is the gravity acceleration. dp is the particle size of the particle. v is the motion viscosity of the fluid. μ is the kinetic viscosity. ε0 is usually 0.4.（When the terminal R quasi-number of the particles is less than 0.2, the inertial force of the particles in the fluid is negligible, and the expansion index(nRe) is calculated by using only the average particle size（dm） and the chromatographic column inner diameter(dc).）
However, if other action factors are considered (not only the role of the viscosity force in the relative movement of particles and fluid), the Stokes formula will produce large errors. Therefore, Martin et al. find it by introducing the Gallileo dimensionless number and by establishing its relation to the terminal Reynolds dimensionless number.
nMar is the expansion index of Martin obtained by experiment. To be closer to the experiment, simple corrections to the partial formula are made.
Our hardware mode diagram is as follows:
Here is our video.
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References arrow_downward
- 赵珺，以环糊精为基质的扩张床吸附剂的制备及银杏黄酮的分离[博士学位论文]，浙江大学，2014：33-68
