Studies On Purification, Gene Cloning And Expression Of Insecticidal Protein

Locusts are among the most harmful pests to China's grasslands. Increasing awareness of the environmental risk associated with the exclusive use of chemical insecticides has given rise to an urgent need to develop biologic control agents as supplements or alternatives to chemical pesticides. Thus biocontrol technology emerges as the time require, and is increasingly regarded.A pathogen strain HR-3 was isolated from naturally dead grasshoppers, it corresponded to S. marcescens. The results of testing the insecticidal activity of S. marcescens HR-3 culture filtrates showed that the insecticidal activity factors of HR-3 was insecticidal protein.Insecticidal protein from Serratia marcescens HR-3 was purified by ammonium sulfate precipitation, DEAE-Sepharose Fast Flow, Sephacryl S-200 gel filtration and native SDS-PAGE cuting method. The final yield was about approximately 4.5 mg insecticidal protein/l. The purified insecticidal protein migrated as a single band on SDS-PAGE with estimated molecular weight of 60 kDa。Serratia marcescens secretes many known extracellular proteins, including nuclease, phospholipase, hemolysin, siderophore, chitinase, protease, and lipase .Because these extracellular factors are hydrolytic in nature, it is reasonable to hypothesize that one or more of the factors may directly contribute to insecticidal...