| Riboflavin-5′-phosphate, also named flavin mononucleotide (FMN), is the ramification product of riboflavin, and plays an very important role in the system of bioreaction. Consequently, it has a prosper market future, such as high concentration injection for the therapy of lack of vitamin, the addition of feed and so on. However, present the industrial product of riboflavin-5′-phosphate mostly comes from chemosynthesis,and hence has a comparatively high cost..In this study, the method of biosynthesis was discussed. The ribR gene in Bacillus subtilis encodes monofunctional flavin kinase, which would convert riboflavin to FMN. We have constructed plasmid pHP13-VR which carries the ribR gene and a strong promoter. Transformation of pHP13-VR into the overproduce-riboflavin-strain B.subtilis 24A1 makes the ribR gene overexpressed, results in the strongly reduction of riboflavin production. Fermentation of the engineered strain B.subtilis 25 shows that the riboflavin production is nearly 50% lower than that of the original riboflavin-produce strain, but no FMN was detected. The results indicate that overexpression of ribR gene greatly restrains the expression of riboflavin synthesis. But the FMN does not acuumulate in the cell.This study has succeeded in modifying B.subtilis 24A1 for the first step. However, producing FMN by microorganism methods needs further study. And the application of the microbiological methods would be greatly reduce the production cost. |
