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The primary problem in producing fuel ethanol through microorganism fermentation with lignocellulose is the strain. We constructed a URA3-directed low copy integration-expression plasmid pZMYBX1 and rDNA-directed high copy integration-expression plasmid pZMYX2. Using the lithium acetate transformation method, we co-transformed the linearized plasmid pZMYBX1 (StuI) and pZMYX2 (HpaI) into theS. cerevisiaecells. Ultimately, we obtain three recombinants: HDY-ZMYWBG1, HDY-ZMYWBG2 and HDY-ZMYWBG3. The ethanol yield for HDY-ZMYWBG1 and HDY-ZMYWBG3 are 0.368 g/g and 0.365 g/g, respectively, which are higher than the 0.330 g/g yield for W5. This findings show that the xylose metabolic pathway could be introduced into theS. cerevisiaeto produce an alternative strain for the production of biological ethanol from lignocellulose substrate.

In this paper, a static electromagnetic field problem will be solved. The method to solve the problem is Finite Difference Method ( FDM ). The software MATLAB is the main environment used to finish the numerical computing. Finally, we found using Finite Difference Method to solve a static electromagnetic field problem is quite convenient. We also can draw the two-dimension and three-dimension graph of the distribution of the electromagnetic field. Furthermore, we discuss the advantages of using FDM to solve the problem, and the disadvantages still exist in this method.