Abstract

We isolated a 10 kb Bam HI fragment originated from the chromosome of a H₂O₂-resistant mutant strain of Streptomyces coelicolor, which confer H₂O₂-resistance to S. lividance upon transformation. Among various subclones ot 10kb Bam HI fragment tested for their H₂O₂-resistant phenotype in S. lividans, a subclone containing 5.2 kb Bam HI-BglII fragment was found to be responsible for H₂O₂-resistance. The plasmid containing this 5.2 kb fragment was then transformed into S. coellicolor A3(2) at early and tested for their phenotype of H₂O₂-resistance and the change in various enzymes whose activity can be stained in the gel. We found out that the 5.2 kb insert DNA conferred H₂O₂-resisstance in S. coelicolor A3(2) at early phase of cell growth. The presence of this DNA also resulted in higher level of peroxidase compared with the wild type cell containing parental vector (pIJ702) only. Esterase activity was also higher in this clone. However, alcohol dehydrogenase activity decreased compared with the wild type. These results suggest that the presence of a gene in 5.2 kb BamHI-BglII DNA fragment causes multiple changes in S. coelicolor related to its response against hydrogen peroxide. The result also implies that not only peroxidase but also esterase may function in the defencse meahsnism agianst H₂O₂.

• Keywords: S. coelicolor; H₂O₂resistance gene; peroxidase; esterase; alcohol dehydrogenase; activity staining