Modeling
The numerical model was applied to investigate the time fermentation of butanol concentration and OD600,and a three-dimensional model of time-butanol concentration-OD600 surface was established. Table 1 presents the experimental data of time fermentation of butanol concentration and OD600.
        Table 1. Effect of fermentation time on butanol concentration and OD600
Time (h) Butanol concentration(mg/L) OD600
0 0.00 0.00
48 37.80 3.13
69 41.07 3.47
95 45.85 3.24
159 44.64 2.44
Steps : 1. Using Matlab for spline interpolation ; 2.Get the time corresponding to the maximum value ; 3.Make interpolation curve.
Coding
      
        clear;clc;
        t0=[0 48 69 95 159];
        Butanol0=[0.00 37.80 41.07 45.85 44.64];
        od600_0=[0 3.13 3.47 3.24 2.44];
        t=[0:160];
        Butanol=interp1(t0,Butanol0,t,'spline');
        od600=interp1(t0,od600_0,t,'spline')
        i=find(Butanol==max(Butanol));
        j=find(od600==max(od600));
        tmax1=t(i)
        tmax2=t(j)
        Butanolmax=max(Butanol)
        od600max=max(od600)
        figure(1)
        plot(t,Butanol,'linewidth',2')
        hold on 
        plot(tmax1,Butanolmax,'r*')
        hold off
        figure(2)
        plot(t,od600,'linewidth',2')
        hold on 
        plot(tmax2,od600max,'r*')
        hold off
Figure 1 : Illustration of model of butanol concentration and time
Figure 2 : Illustration of model of OD600 and time
The maximum butanol concentration appeared near 129 hours, and the maximum OD600 appeared near 72 hours.
The 3D simulated images of the three variables are as follows:
Figure 3. A three-dimensional model of time-butanol concentration-OD600 surface.
The model predicted that the butanol concentration and OD600 of pLY15-opt / Streptococcus.Butanol concentration and OD600 were optimal at 80-90 h. Finally, it lays a foundation for the construction of a high-yield butanol-producing strain to meet the needs of industrial production.