Antagonistic bacteria 2-Q-9 against Ralstonia solanacearum indicated that the relationship between phylogenetic and Brevibacillus choshinensis was the closest based on the results of phylogenetic analysis of 16S rDNA sequence.The 16S rDNA sequence was registered at GenBank database with the accession number FJ613127.Based on one fragment of amino acid sequences of antibacterial peptides which secreted by Brevibacillus choshinensis strain 2-Q-9,degenerate primers were designed.A target fragment with a full length of 780 bp was amplified using genome walking.BLAST indicated that this sequence is similar to the sequence of transcriptional repressor CodY with amino acid sequence similarity 77%,so it was a member of CodY family.The full length sequence was registered at GenBank database with the accession number FJ613128.