Engineering a vitamin B12 high-throughput screening system by riboswitch sensor in Sinorhizobium meliloti

As a very important coenzyme in the cell metabolism, Vitamin B12 (cobalamin, VB12) has been widely used in food and medicine fields. The complete biosynthesis of VB12 requires approximately 30 genes, but overexpression of these genes did not result in expected increase of VB12 production.