Abstract:［Objective］We analyzed the transcriptional regulation of aco gene cluster and the phenotype of acoR mutant，to determine the effect of acoR deletion on sporulation efficiency and Cry protein production． ［Methods］Sequence of aco gene cluster in Bacillus thuringiensis was analyzed by sequence alignment．RT-PCR was carried out to reveal the transcriptional units of the aco gene cluster．acoR insertion mutant was constructed by homologous recombination．Transcriptional activity was analyzed by promoter fusions with lacZ gene．Comparison of the Cry1Ac protein production was determined by protein quantitation．［Results］The aco gene cluster was composed of four genes．The acoABCL formed one transcriptional unit．The transcriptional activity of acoA promoter sharply decreased in sigL and acoR mutants，respectively． Deletion of acoR had no effect on growth and Cry protein production，but decreased the motility of cells and sporulation efficiency．［Conclusion］The acoR gene cluster is controlled by Sigma 54 and activated by AcoR． Deletion of acoR has no effect on Cry protein production，but decreased the motility of the cells.