ribR基因在产核黄素枯草芽胞杆菌中的组成型表达

枯草芽胞杆菌ribR基因编码单功能黄素激酶,催化核黄素转化为FMN.ribR基因作为ytmI-ytnM操纵子的一部分,其表达调控机制尚不清楚.用PCR方法扩增了枯草芽胞杆菌veg基因的启动子vegP,连接到大肠杆菌-枯草杆菌穿梭载体pHP13上,构建了表达型重组质粒pHP13-V.用PCR方法扩增了ribR基因,连接到pHP13-V上,构建了重组质粒pHP13-VR.将pHP13-VR转化产核黄素的枯草芽胞杆菌24A1,使ribR基因在24A1中组成型表达,得到菌株24A1/pHP13-VR.与24A1相比,24A1/pHP13-VR菌落由亮黄色变为微黄色,核黄素产量下降为1.26 mg/mL,下降了45%.结果说明,在ribC基因突变背景的过量合成核黄素枯草芽胞杆菌中,ribR基因的存在对菌株的核黄素发酵有一定的抑制作用.

The Constitutive Expression of ribR Gene in Riboflavin-producing Bacillus subtilis

The ribR gene in Bacillus subtilis encodes a monofunctional riboflavin kinase which converts riboflavin into FMN. As part of ytmI-ytnM operon, the regulation mechanism of ribR gene is not clear. Recombination plasmid pHP13-V, which was used for expression of ribR, was constructed by ligation of promoter of veg gene in B subtilis into E. coli-B, subtilis shuttle vector pHP13. The ribR gene was amplified by PCR, cloned into pHP13-V and trans- formed into 24Al. Compared with the 24Al, the colony color of transformant 24Al/pHP13- VR was changed from bright yellow into pale yellow, and the yield of riboflavin was fall to 1. 26 mg/mL, had a 45 % decline. The result indicated that the expression of ribR gene suppressed B subtilis ribC mutant strain which has riboflavin overproduction phenotype.