Cloning and Functional Confirmation of XFsacA Gene from Bacillus subtilis XF1

Bacillus subtilis XF1, which is patented and a very efficient biocontrol agent to control clubroot disease of cruciferous crops, grows very quickly when sucrose is used as carbon source. To elucidate the growth promotion mechanism of sucrose, the XFsacA gene, encoding a key enzyme for sucrose metabolism, was amplified by PCR and sequenced. Its amino acid sequence has 97% homolog to Bacillus subtilis B168 except 12 amino acids replacement. The coding region of the gene was inserted into plasmid pQE30 to construct an expression plasmid, pQE30-XFsacA. After pQE30-XFsacA was transformed into Escherichia coli BL21, which could not use sucrose, a protein band about 54 000 detected by SDS PAGE analysis indicated the gene was successfully expressed in BL21. The function of XFsacA gene was confirmed by the transformed BL21 having the ability to grow and survive in M9 medium with sucrose as sole carbon source. The data indicated that the replacement of 12 amino acids of XFsacA in XF1 strain might improve the efficiency in use of sucrose，and cloning and functional expression of XFsacA in E. coli could be a good strategy for developing metabolic engineered E. coli strain to use sucrose.