Deletion of spoIVF operon affects the sporulation and the production of crystal in Bacillus thuringiensis G03

Abstract:

The spoIVF operon exists in Bacillus universally. Two proteins encoded by the spoIVF operon are essential for the sporulation of Bacillus subtilis. In this study，a spoIVF operon disruption mutant G03（spoIVF-），in which the spoIVF operon was deleted，was constructed by homologous recombination. The result showed that the mutant strain lost the ability of sporulation. At the same time，the expression of Insecticidal Crystal Protein(ICP) was severely reduced in G03（spoIVF-）mutant strain and resulted in no crystals. The lacZ gene was fused with the promoter of the cry1Aa gene and expressed in mutant strain G03（spoIVF-）and G03 wild strain. The activity of β-galactosidase much lower in mutant G03（spoIVF-） strain than in the wild-type strain. This further suggested that the activity of σ^E and σ^K factors was affected in mutant G03（spoIVF-） strain. The ability of sporulation and production of Insecticide Crystal Protein was complemented by the expression of spoIVF operon through the vector of pSTK in the mutant strain. In all，The spoIVF operon is essential for the sporulation and the expression of cry gene controlled by σ^E and σ^K factors.

Key words:Bacillus thuringiensis; sporulation; crystal; spoIVF operon