Knockout Of Hprk Gene And Characterization Of Fermentation Of Riboflavin-Producing Bacillus Subtilis

In bacillus subtilis the HPr protein participate either in the glucose transportation,or in the carbon catabolite repression effect.the phosphoenol pyruvate:sugar phosphotransferase system (PEP-PTS) is the main glucose transportation system in B.subtilis.The HPr protein is phosphorylated at His-15 forming HPr-His15-P transferring phosphate group from HPr to EIIa.While HprK/P phosphorylate HPr at Ser46 forming HPr-Ser46-P as Co-effector of CcpA.The Knockout of CcpA gene increases the amount of FBP in vivo. And FBP could activate HPr kinase.So when CcpA is deleted, most part of the HPr will be phosphorylated at Ser-46. HPr-Ser46-P cannot participate in the transportation of glucose.Absorpton of glucose is blocked.In this study, obstacle of glucose absorption is relieved by disruption of hprk gene.The obtained B.subtilisZHc/pMX45 can tolerate glucose at the concentration of 12%.When the glucose concentration is 10%, production of riboflavin reaches the peak value of 4.374mg/ml, 19.2% higher than that of B.subtilis24A1/pMX45 at the glucose concentration of 8%.