趋化信号转导基因cheA突变对Pseudomonas putida DLL-1甲基对硫磷的趋化性及原位降解的影响

Pseudomonas putida DLL-1是一株甲基对硫磷(MP)高效降解菌株,同时对MP具有趋化性。cheA基因是菌株趋化信号转导过程中负责编码组氨酸激酶的基因,为了研究菌株趋化性在农药原位降解中的作用,通过基因打靶的方式使P.putida DLL-1染色体上单拷贝的cheA基因失活,成功地获得了MP的趋化突变株P.putida DAK,突变株与野生菌株生长能力没有显著差异。通过土壤盆钵试验(MP浓度为50mg/kg),发现在灭菌与未灭菌土壤中趋化突变株对MP的降解能力低于原始出发菌株DLL-1约20%~30%,说明菌株DLL-1趋化性的丧失会减慢其对农药的降解,趋化性在农药的原位降解过程中发挥重要作用。

Effect of mutation of chemotaxis signal transduction gene cheA in Pseudomonas putida DLL-1 on its chemotaxis and methyl parathion biodegradation

Pseudomonas putida DLL-1 is a high effective methyl parathion (MP) degrading strain, which is also of chemotaxis to MP. cheA, responsible for coding histidine kinase, plays an important role in bacterial chemotaxis signal transduction. In order to study the effect of bacterial chemotaxis on in-situ biodegradation of pesticides, cheA in chromosome of P. putida DLL-1 was mutated by gene-targeting and successfully obtained a MP-chemotaxis mutant DAK. The mutant DAK shows the same growth ability as wild-type DLL-1 in LB medium. The degrading rate of 50 mg/kg MP in non-sterile and sterile soil of chemotaxis mutant DAK is about 20%-30% lower than that of wild-type bacterial DLL-1. Lose of chemotaxis in DLL-1 would decline its degradation ability of MP. It was demonstrated that chemotaxis plays an important role in the in-situ biodegradation of pesticides.