Cloning and expression of the Escherichia coli D-xylose isomerase gene in Bacillus subtilis.

A DNA fragment containing the Escherichia coli D-xylose isomerase gene and D-xylulokinase gene had been isolated from an E. coli genomic bank constructed by Clarke and Carbon. The D-xylose isomerase gene coding for the synthesis of an important industrial enzyme, xylose isomerase, was subcloned into a Bacillus-E. coli bifunctional plasmid. It was found that the intact E. coli gene was not expressed in B. subtilis, a host traditionally used to produce industrial enzymes. An attempt was then made to express the E. coli gene in B. subtilis by fusion of the E. coli xylose isomerase structural gene downstream to the promoter of the penicillinase gene isolated from Bacillus licheniformis. Two such fused genes were constructed and they were found able to be expressed in both B. subtilis and E. coli.