Screening and Identification of Antagonistic Bacillus Strains against Pathogens of Fusarium Dry Rot and Black Scurf in Potato

Abstract

Rhizosphere soil under potato plants of 96 plots in four different treatments of continuous cropping were sampled via five-sited sampling method in Tiaoshan farm, Jingtai County, Gansu Province. The soil samples were plated onto LB medium via dilution with Bacillus strains, and 625 Bacillus strains were obtained from 96 potato plots. The results of statistical analysis indicated that the quantity of Bacillus strains tended to reduce with years’ increasing of potato continuous cropping, while tended to go up after six years’ continuous cropping. The Bacillus strains antagonistic to four pathogen isolates in three species(Fusarium solani FSI, F. sambucinum FSM,Rhizoctonia solani RS1 and RS2) were screened by dual plate method, and quantity of antagonistic Bacillus strains declined. Two Bacillus strains with years increasing of continuous cropping antagonistic to the pathogens were identified as B. atrophaeus via combination of physiological, biochemical characteristics and gyrB gene sequences.