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

<p>To expand the usage of endophytes in agriculture and in forestry, the insecticidal gene <i>cry218</i> of <i>Bacillus thuringiensis</i> was introduced into a poplar bacterial endophyte <i>Burkholderia pyrrocinia</i> JK-SH007. The <i>cry218</i> gene was cloned by polymerase chain reaction (PCR) and was inserted into a PHKT<sub>2</sub> 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 <i>in planta</i>. The toxicity of the expressed insecticidal protein was analysed on second instar silkworm. The regression equation showed that the median lethal concentration (LC<sub>50</sub>) of the insecticidal protein was 0.77 (0.57–1.04) g/L at 72 h. The insecticidal bacteria genetically modified in this study have laid the foundation for further exploitation of biocontrol bacteria.</p>