We have got several clones from Serratia marcescens which stimulated the cells to use maltose as a carbon source in E. coli TP2139 (${Delta}$lac, ${Delta}$crp). One of the cloned genes, pCKB13, was further analyzed. In order to find whether the increased expression of the gene under the direction of maltose metabolism, we constructed several recombinant subclones. We have confirmed that the clone, pCKB13 codes Coenzyme A transferase gene by partial nucleotide sequencing in the terminal region. The enzyme activity of Coenzyme A transferase increased after introduction of the multicopy of the cloned gene in E. coli. The recombinant proteins expressed by multicopy and induction with IPTG, two polypeptide of 26-and 28-kDa, were confirmed by SDS-PAGE. Southern hybridization analysis confirmed that the cloned DNA fragment was originated from S. marcescens chromosomal DNA.