Effect of Quorum Sensing response regulator nprR deletion on expression of Cry protein in Bacillus thuringiensis

Abstract:

Abstract: [Objective] The role of Quroum Sensing response regulator nprR on the expression of Cry protein in B. thuringiensis HD-73 was studied. [Methods] The nprR gene deletion mutant HD73 (ΔnprR) was constructed by using of homologous recombination. Beta-galactosidase assay of cry1Ac′-lacZ gene fusion and SDS-PAGE in both HD-73 and HD73 (ΔnprR) strains were performed to analyze the effect of nprR gene deletion on expression of cry1Ac gene. [Results] Beta-galactosidase assay of nprR′-lacZ in both LB and Schaeffer’s sporulation medium showed nprR gene in B. thuringiensis was initially transcripted at T0 (end of Logarithmic growth phase) and keeping expression in stationary phase. Beta-galactosidase assay of cry1Ac′-lacZ and SDS-PAGE indicated that expression of cry1Ac gene in HD73 (ΔnprR) was stronger than that in HD-73 during transition phase and early stationary phase. However, Cry expressed product between HD-73 and HD73 (ΔnprR） in LB medium has no significant difference when crystal and spore were released. [Conclusion] The deletion of nprR increased expression and transcription activity of cry1Ac during transition and early stationary phase in rich media.