[Screening and identification of plant growth-promoting rhizobacteria]

The interaction between plant growth promoting rhizobacteria (PGPR) and plants can be unstable, PGPR with PGP activities may be well adapted to particular soil environment. Based on this, we isolated and identified PGPRs from different rhizosphere soils according to their multiple mechanisms.

Preliminary screening of PGPRs under the premises of PGPR may having the abilities of N2-fixing, phosphate and potassium solubilization, and resistance against six common pathogenic fungi as well as rhizosphere colonization. After that, multiple PGP activities were detected in vitro. Finally, PGPRs were classified and identified by combining physiological and biochemical tests and 16S rRNA gene sequence analysis.

Fourteen strains having various mechanisms of PGP activities such as NH3, IAA, HCN, siderophore, antibiotics production, phosphate and potassium solubilization, and N2-fixing were isolated from different rhizosphere soils in Yangzhou and Yancheng, Jiangsu province. These 14 isolates could be identified as Pseudomonas (7 isolates), Paenibacillus (3 isolates), Bacillus (2 isolates), Burkholderia (1 isolate) and Erwinia (1 isolate).

Isolates with multiple PGP activities can also be rhizospheric competent, able to survive and colonize in the rhizosphere, providing promising isolates for PGPRs combination to resolve the challenges in field application of PGPR.