Engineering the bacterial endophyte Burkholderia pyrrocinia JK-SH007 for the control of lepidoptera larvae by introducing the cry218 genes of Bacillus thuringiensis

To expand the usage of endophytes in agriculture and in forestry, the insecticidal gene cry218 of Bacillus thuringiensis was introduced into a poplar bacterial endophyte Burkholderia pyrrocinia JK-SH007. The cry218 gene was cloned by polymerase chain reaction (PCR) and was inserted into a PHKT2 expression vector that was introduced into the bacterial endophyte JK-SH007. By using sodium dodecyl sulphate polyacryl amide gel electrophoresis (SDS-PAGE) and western blotting, we confirmed that the engineered bacterial endophyte was successfully constructed, and it harboured insecticidal function after the bioassay in planta. The toxicity of the expressed insecticidal protein was analysed on second instar silkworm. The regression equation showed that the median lethal concentration (LC50) of the insecticidal protein was 0.77 (0.57-1.04) g/L at 72h. The insecticidal bacteria genetically modified in this study have laid the foundation for further exploitation of biocontrol bacteria.