Cloning and expression of an extracellular-agarase gene from Streptomyces coelicolor A3(2) in Streptomyces lividans 66

An extracellular agarase gene was cloned from Streptomyces coelicolor A3(2) strain M130 into S. lividans 66 using the multicopy plasmid vector pIJ702. Various deletion derivatives of the initial clone (pMT605) were obtained by in vitro and in vivo methods. This allowed the gene to be localised to a 1.9-kb segment of DNA. The agarase enzyme was overproduced (up to 500 times) and exported efficiently into the medium. The agarase protein was identified as a 28-kDal band after sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE); in the case of one derivative, pMT608, this band accounted for nearly 50% of the total extracellular protein. Differences in agarase production between the deletion derivatives correlated well with plasmid stability.