Effects of the β-lactamase gene and orientation of the kanamycin-resistance gene in plasmid pCED3 on the growth of Bacillus subtilis

Abstract

Recombinant plasmid pCED3 inhibits growth of Bacillus subtilis cultures but in Escherichia coli, the plasmid has no effect on growth. We previously found that transcription from the tms promoter inhibits the expression of the plasmid-encoded kanamycin resistance gene (KNT) in B. subtilis resulting in the reduction of both β-galactosidase expression and cell growth rate in the presence of kanamycin. This effect was found to be markedly diminished by changing the orientation of the KNT gene on the plasmid. The primary β-lactamase gene product, which is not processed in B. subtilis, did not take part in growth inhibition. Thus the negative effect of tms-directed transcription on the cell's resistance to kanamycin and the high amount of pUB110-derived plasmid DNA in B. subtilis can account for the differential growth effect on B. subtilis and E. coli that plasmid pCED3 exerts.