标题：Recombineering Pseudomonas protegens CHA0: An innovative approach that improves nitrogen fixation with impressive bactericidal potency
作者：Yu, Fangnan; Jing, Xiaoshu; Li, Xiaochen; Wang, Hailong; Chen, Hanna; Zhong, Lin; Yin, Jia; Pan, Deng; Yin, Yulong; Fu, Jun; Xia, 更多 作者机构：[Yu, Fangnan; Jing, Xiaoshu; Li, Xiaochen; Wang, Hailong; Zhong, Lin; Yin, Jia; Fu, Jun; Bian, Xiaoying; Tu, Qiang; Zhang, Youming] Shandong Univ, Hel 更多
通讯作者：Tu, Qiang;Tu, Q;Zhang, YM
通讯作者地址：[Tu, Q; Zhang, YM]Shandong Univ, Helmholtz Inst Biotechnol, State Key Lab Microbial Technol, Sch Life Sci,Suzhou Inst, Qingdao 266237, Peoples R China 更多
关键词：Pseudomonas protegens CHA0 retS gene; Nitrogen-fixation island (Nif);; Antibacterial activity; Fermentation conditions
摘要：Pseudomonas protegens CHA0 is a well-characterized, root-colonizing bacterium with broad-spectrum biocontrol ability. Therefore, it has a great potential to curb plant diseases and to partly replace synthetic chemical pesticides that are harmful to humans. Here, we obtained the multifunctional mutant CHA0-Delta retS-Nif via Red/ET recombineering technology. After deletion of the retS gene and integration of the nitrogen-fixing gene island (Nif) into the CHA0 genome, the resulting mutant, CHA0-Delta retS-Nif, manifested improved both bactericidal activity and biological nitrogen-fixation function. A pot experiment of Arabidopsis thaliana indicated that the strain CHA0-Delta retS-Nif promoted plant growth via expressing several secondary factors, such as the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) and nitrogenase. In order to grow this biocontrol strain at an industrial level, the growth conditions in a 1 L continuous-flow fermenter were optimized to 28 degrees C, pH of 7.0, and 600 rpm. Moreover, growth experiments in a 5 L fermenter with these optimal growth conditions yielded the maximum cell density, providing vital insights for the industrialization and large-scale fermentation of P. protegens CHA0 for further applications. CHA0-Delta retS-Nif possesses both bactericidal and nitrogen-fixation activities and thus could be used as a biological agent to enhance crop production.