| Bacteria with antagonistic activity against potato black scurf pathogen (Rhizoctonia solani) were isolated from the rhizosphere soils with different years of continuous cropping in hill farm of Jingtai county, Gansu Province. Antagonistic bacteria were isolated from soil through dilution plates and antagonistic plates. Based on the morphological characteristics, physiological and biochemical tests, and 16SrDNA sequencing analysis were performed. Single factor experiment design was carried out to discuss the growth conditions of strain G1. One of the isolated strains, G1, which showed the strongest antagonism, was selected from 108 bacterial strains. It produced an inhibition zone with 6.0mm width and > 2.5cm diameter, and an inhibitory rate at 66.7% through confronting incubation. According to the morphological characteristics, physiological and biochemical tests, and 16SrDNA sequence analyses, it was preliminarily identified to be Paenibacillus sp. In addition, a single factor experiment design was carried out to examine the optimal growth conditions for G1. The results showed that the bacteria could grow at 4℃～45℃ with pH 5～10 and salt concentration 0 to 50 g·L-1. The optimal conditions for G1 growth was found to be 37℃ inoculation with pH at 7 using sucrose and peptone as carbon and nitrogen sources respectively, as well as with a salt concentration at 10 g·L-1. In conclusion, the newly selected Paenibacillus sp. G1 showed broad inhibition zone, with a stable effect against potato black scurf pathogen (Rhizoctonia solani). The growth condition for G1 was similar to those for potato growth, owning necessary criteria as a good biocontrol strain. |