[Expression of xylE gene in Bacillus stearothermophilus]

Using the gene expression vector pFDC11 for Bacillus stearothermophilus CU21, a recombinant plasmid pFDX1 was constructed, which carries the Pseudomonas-derived xylE gene coding for Catechol 2,3-dioxygenase (CatO2ase). CatO2ase activity can be detected from CU21 (pFDX1) cells grown at 48 degrees C. This result indicates that the promoterless xylE gene can be expressed in a thermophilic host under the direction of a promoter from a thermophilic bacterium. By selecting Kmr mutants at elevated growth temperature, a segregant CU21-161 was obtained, the xylE gene expression of which at 55 degrees C and 60 degrees C was much higher than that of the parental strain. A method for CatO2ase assay with suspension of intact cells was also reported in this paper.